Spectroscopic or microscopic apparatus and operating method

Abstract

The present invention provides a spectroscopic or microscopic instrument that achieves precise control while minimizing topographical variations on the surface of the sample being analyzed. [Solution] A spectroscopic or microscopic device operates by measuring the intensity profile of a laser beam directed along a trajectory through the device, with the intensity profile measured at a reference position in the trajectory. The shape of the laser beam is constructed based on the measured intensity profile.

Description

Technical Field

[0001] The present invention relates to a microscopic or spectroscopic device and a method of operating such a device.

Background Art

[0002] Accurate and reliable spectroscopic or microscopic analysis of the bulk, surface, and any subsurface-embedded interfaces of solids is key to understanding the manufacturing quality and properties of technically important materials and devices, the development of new multifunctional materials, and material failure.

[0003] Well-known and highly developed surface chemical analysis methods include spectroscopic and microscopic techniques. Spectroscopic techniques can involve probing the surface with electromagnetic radiation, an electron beam, ions, or a laser beam. Microscopic techniques can involve probing the surface with an electron beam. Well-known spectroscopic techniques include, for example, X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), secondary ion mass spectrometry (SIMS), and laser-induced breakdown spectroscopy (LIBS). Well-known microscopic techniques can be X-ray or electron microscopic techniques. Well-known electron microscopic techniques include, for example, scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

[0004] Two of the most widely used and highly developed surface chemical analysis methods are electron spectroscopic techniques, namely, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). XPS is a photoelectron spectroscopy in which the electron core level and valence band spectra from atoms in a solid are obtained by irradiating the material with a beam of X-rays. Chemical state information is extracted from the spectrum in the form of an electron binding energy shift of the electrons due to changes in the local chemical environment. AES is similar to XPS but is based on the analysis of Auger electrons emitted as part of the relaxation process after core level excitation. In the case of AES, excitation occurs through incident radiation, which can be an X-ray or an electron beam.

[0005] In many cases, it is important to determine the chemical composition at depths greater than those reached by XPS / AES analysis. To achieve this, material must be removed from the surface, and XPS / AES analysis must be repeated on the new surface revealed by the material removal. This cycle of material removal and XPS / AES analysis continues until the chemical composition is recorded for the depth of interest. The elemental composition at each level is calculated and plotted as a function of the number of cycles, known as the depth profile. When depth is measured, assuming a constant material removal rate, the depth profile can be plotted in terms of chemical composition as a function of the etched depth.

[0006] In XPS / AES depth profiling processes, material removal is typically achieved using ion beam bombardment with an ion gun mounted on a spectrometer. The ion gun can generate a beam of monatomic ions or (polyatomic) cluster ions. The ion beam is aligned with an X-ray spot (for XPS) or an electron beam (for AES) on the surface of the sample, enabling the cyclic depth profiling process to be carried out. The ion gun accelerates ions to high energies, and upon impact with the surface, these energies are sufficient to remove surface atoms in a process known as sputtering. However, many materials are ion beam sensitive. This means that the sputtering process damages the underlying surface, leading to changes in chemical composition recorded by XPS / AES across the entire depth profile. In compounds, this can take the form of preferential sputtering, where one element is sputtered more than others, and is observed particularly in inorganic materials. In polymer materials, in addition to preferential sputtering of elements such as oxygen from the polymer, the ion beam also damages the molecular structure. Therefore, in the case of ion beam-sensitive materials, the ability of XPS / AES to provide accurate quantitative compositional information may be impaired, and an incorrect chemical composition may be recorded throughout the XPS / AES sputtering depth profile. Furthermore, the degree of preferred sputtering varies depending on the ion beam conditions and material composition. It is not possible to reliably predict the degree of preferred sputtering for any new material or ion beam conditions. Therefore, when depth profiling potentially ion beam-sensitive materials, analysts cannot know whether preferred sputtering is altering the apparent composition of the collected depth profile. The inability to know the incorrect composition recorded during depth profiling and whether this is occurring in the material under investigation is a significant problem for techniques that are considered capable of providing accurate chemical composition. Cluster ion beams have enabled a substantial reduction in damage to most thermal polymers during depth profiling. Cluster ion beams have also been shown to reduce, but not eliminate, preferred sputtering in metal oxides.However, the use of cluster ion beams also introduced new problems stemming from thermal spikes associated with cluster ion beam collisions.

[0007] WO2024 / 052232, incorporated herein by reference, attempts to address some of these problems by using laser pulses for material ablation in combination with electron spectroscopy techniques such as XPS and AES. It describes a method comprising irradiating an area with one or more pulses of laser, irradiating at least a portion of the area with an excitation beam of electrons or electromagnetic radiation, measuring the intensity and energy of electrons emitted from at least a portion of the area of ​​the sample as a result of the excitation beam, and repeating the steps of ablating the material, irradiating it with the excitation beam, measuring the intensity and energy to determine a quantitative surface depth profile and obtain the chemical composition of at least a portion of the sample. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] WO2024 / 052232 [Patent Document 2] GB2411763A [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, depth profiling using laser beams requires delicate and controlled removal of material from the sample. Therefore, precise control of the laser beam used to perform sample ablation is essential for optimizing ablation conditions, achieving optimal crater formation, and thus achieving sample depth profiling. It would be desirable to achieve such precise control while minimizing topographical variations on the surface of the sample being analyzed. [Means for solving the problem]

[0010] According to a first embodiment, the present invention provides a method for operating a spectroscopic or microscopic apparatus, the method comprising measuring the intensity profile of a laser beam directed along a trajectory through the apparatus, particularly in a vacuum, wherein the intensity profile is measured at a reference position in the trajectory, and constructing the shape of the laser beam based on the measured intensity profile. In particular, the intensity profile is measured by irradiating a profiling element with the laser beam, the profiling element intersecting the laser beam at a reference position.

[0011] By measuring the intensity profile of the laser beam at a reference position and then shaping the laser beam based on the measured intensity profile, the laser beam profile can be precisely controlled and optimized in situ. This is advantageous for ensuring accurate material removal from the sample during subsequent ablation and subsequent precise depth profiling.

[0012] The intensity profile is the spatial intensity profile of a laser beam. The intensity profile can be the intensity distribution across the beamwidth of the laser beam at a reference position. As used herein, beamwidth refers to the diameter of the beam spot size.

[0013] Configuring as used herein in the context of shaping a laser beam based on a measured intensity profile means adjusting the shape of the laser beam based on the measured intensity profile as needed, and maintaining the laser beam in its current shape if no adjustment is required based on the measured intensity profile.

[0014] The reference position may be at a fixed distance from the focal point of the laser beam, which is referred to herein as the reference distance RD. The reference distance may be zero. Preferably, the reference distance is a non-zero distance such that the reference position is located away from the focal point of the laser beam.

[0015] The reference position may be upstream of the laser beam's focal point. The reference distance may be, for example, 0.01 to 100 mm from the laser beam's focal point, preferably 0.1 to 10 mm, and more preferably 1 to 5 mm. The laser beam's focal point may be defined as the focal distance from the objective lens to which the laser beam is focused when directed along its trajectory through the device. The reference distance may be, for example, within the range of 0.01% to 5% of the focal length, preferably 0.1% to 5%, and more preferably 0.5% to 2.5% of the focal length. The reference distance may be predetermined. The reference distance may be selected by the user.

[0016] The step of measuring the intensity profile of a laser beam at a reference position may include irradiating a profiling element with the laser beam, and during the step of measuring the intensity profile of the laser beam, the profiling element intersects with the laser beam at the reference position. In particular, the surface of the profiling element may intersect with the laser beam at the reference position during the step of measuring the intensity profile of the laser beam. The intersection of the profiling element and the laser beam refers to at least a portion of the profiling element and the laser beam that intersect to some extent in space, such that there is at least some overlap between them. The intersection between the profiling element and the laser beam does not require that the laser beam has the same spatial range as the profiling element at the intersection. During the step of measuring the intensity profile of the laser beam, at least a portion of the surface of the profiling element may overlap with the laser beam. The plane of the surface of the profiling element that intersects with the laser beam may be called the profiling plane. The laser beam may intersect the profiling plane at a non-zero angle. The laser beam may intersect the profiling plane at an angle of, for example, 5 to 175 degrees. The surface area of ​​a profiling element in the profiling plane may be greater than the beamwidth of the laser beam at the reference position. Alternatively, the area of ​​a profiling element in the profiling plane may be less than the beamwidth of the laser beam at the reference position, and the profiling element may be translated across the area of ​​the laser beam spot at the reference position so that the profiling element scans across the laser beam spot at the reference position. The step of measuring the intensity profile of the laser beam may be referred to herein as the profiling step.

[0017] The profiling element may include a laser-sensitive material. The profiling element may consist of a laser-sensitive material. The profiling element may include a laser-sensitive material coated on a sensor device. The laser-sensitive material may be directly coated on the sensor device (i.e., without any intervening features). The profiling element may consist of a laser sensor material coated on a sensor device. According to embodiments in which the laser-sensitive material is coated on a sensor device, the profiling element may include both the laser-sensitive material and the sensor device. Alternatively, the sensor device may not form part of the profiling element and may be located remotely from the laser-sensitive material. The sensor device may include one or more cameras. The laser-sensitive material and / or the sensor device may be suitable for ultra-high vacuum (UHV) conditions. Typically, sample ablation is performed under vacuum conditions. By employing a profiling element suitable for ultra-high vacuum conditions, it is possible to measure the intensity profile of a laser beam using the profiling element under vacuum conditions, and therefore in situ.

[0018] Laser-sensitive materials may be configured to undergo changes and / or to generate radiation in response to irradiation by a laser beam. Sensor devices may be configured to detect changes in the laser-sensitive material and / or radiation from the laser-sensitive material.

[0019] Laser-sensitive materials may include light-emitting materials configured to emit photons in response to irradiation with a laser beam. The light-emitting material may be phosphorescent or fluorescent. Optionally, the light-emitting material may be an upshift anti-Stokes phosphor for converting infrared laser light into visible light.

[0020] If the profiling element includes or is composed of a laser-sensitive material, the step of measuring the intensity profile of the laser beam at a reference position may include detecting changes or radiation from the laser-sensitive material in response to irradiation of the laser-sensitive material with the laser beam. Changes or radiation from the laser-sensitive material may be detected by a sensor device that may have a laser-sensitive material coated on it or may be located remotely from the laser-sensitive material. Changes or radiation from the laser-sensitive material in response to irradiation of the laser-sensitive material with the laser beam may correlate with the intensity of the laser beam irradiating it. This allows the intensity profile of the laser beam irradiating the laser-sensitive material to be determined based on the detected changes or radiation from the laser-sensitive material. The intensity of radiation from the laser-sensitive material may be proportional to the intensity of the laser beam irradiating it.

[0021] The profiling element may include a laser sensor. The profiling element may consist of a laser sensor. If the profiling element includes or consists of a laser sensor, the laser sensor may be configured to measure the intensity of the laser beam illuminating it. The laser sensor may include one or more cameras. The laser sensor may be suitable for ultra-high vacuum (UHV) conditions. Typically, sample ablation is performed under vacuum conditions and may be performed under ultra-high vacuum conditions. By employing a laser sensor suitable for ultra-high vacuum conditions, it is possible to measure the intensity profile of the laser beam under vacuum conditions, and therefore in situ, with the laser sensor.

[0022] The device may comprise a sample stage. The profiling element may be arranged on the sample stage during the step of measuring the intensity profile. The sample stage may be configured to absorb or dissipate the heat generated by the profiling element when the profiling element is arranged on the sample stage. The sample stage may comprise a heat sink configured to receive the heat generated by the profiling element when the profiling element is arranged on the sample stage. This is particularly advantageous for embodiments employing a profiling element comprising a sensor device having a laser-sensitive material coated thereon, or a profiling element comprising a laser sensor, since a laser sensor or sensor device may generate heat during use, which can lead to overheating and degradation of the performance of the laser sensor or sensor device, especially when the laser sensor or sensor device is arranged in a vacuum chamber during the measurement of the intensity profile of the laser beam.

[0023] The method may include coupling the profiling element to the sample stage before the step of measuring the intensity profile is performed such that the profiling element is coupled to the sample stage during the step of measuring the intensity profile, and decoupling the profiling element from the sample stage after the step of measuring the intensity profile is performed. The coupling may include mechanically and / or electrically coupling and / or thermally coupling the profiling element to the sample stage.

[0024] When the profiling element includes a laser sensor, then optionally, during the step of measuring the intensity profile, the laser sensor can be releasably electrically coupled to the sample stage such that the sample stage transfers power to the laser sensor. The method can further include transferring data from the laser sensor to the processing device when the laser sensor is electrically coupled to the sample stage. The step of transferring data from the laser sensor to the processing device can be performed using a wired connection that optionally includes one or more pairs of twisted wires. Employing pairs of twisted wires for data transfer is advantageous for maintaining signal integrity and reducing noise interference. Optionally, a wired connection that can employ one or more pairs of twisted wires can be used to transfer power to the laser sensor and / or data from the laser sensor.

[0025] When the profiling element includes a laser-sensitive material coated on a sensor device, then during the step of measuring the intensity profile, the sensor device can be releasably electrically coupled to the sample stage such that the sample stage transfers power to the sensor device. The method can further include transferring data from the sensor device to the processing device when the sensor device is electrically coupled to the sample stage. Optionally, the step of transferring data from the sensor device to the processing device can be performed using a wired connection that optionally includes one or more pairs of twisted wires. Employing pairs of twisted wires for data transfer is advantageous for maintaining signal integrity and reducing noise interference. Optionally, a wired connection that can employ one or more pairs of twisted wires can be used to transfer power to the sensor device and / or data from the laser sensor.

[0026] The profiling elements can be supported on a holder. The profiling elements can be directly supported on the holder such that there are no intervening features between them. Mechanical and / or electrical coupling and / or thermal coupling to the sample stage can be achieved via the holder. The holder and / or the sample stage can comprise a wired connection.

[0027] The method may further include, after the step of shaping the laser beam based on the measured intensity profile, ablating a portion of the material from a portion of the sample surface by irradiating that portion with the laser beam. The step of ablating a portion of the material from a portion of the sample surface by irradiating that portion with the laser beam may be called the sample ablation step. Optionally, during the step of ablating a portion of the material from a portion of the sample surface, the portion of the sample surface intersects the laser beam at a reference position. Thus, the laser beam intersects the sample surface during the sample ablation step and intersects the profiling element at the same position (reference position) in the laser beam trajectory during the profiling step. Therefore, the laser beam intensity profile can be measured and adjusted at the same position where the sample ablation is performed. This is advantageous for ensuring accurate removal of material from the sample during ablation. Ensuring accurate removal of material from the sample during ablation is important for subsequent accurate depth profiling.

[0028] A portion of the sample surface ablated by the laser beam may lie in a plane referred to herein as the sampling plane. The laser beam may intersect the sampling plane at a non-zero angle during the ablation of the sample surface. The non-zero angle may be between 5 and 175 degrees. The non-zero angle between the laser beam and the sampling plane during the sample ablation step may be substantially the same as the non-zero angle between the laser beam and the profiling plane during the profiling step. The non-zero angle between the laser beam and the sampling plane during the sample ablation step may be within 5 degrees, preferably within 2 degrees, and more preferably within 1 degree, similar to the non-zero angle between the laser beam and the profiling plane during the profiling step. The sampling plane may be parallel to the profiling plane.

[0029] The method may further include, after the step of ablating material from a portion of the sample surface, performing spectroscopic or microscopic analysis of at least a portion of the ablated portion, optionally, the spectroscopic analysis including X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, and / or laser stimulated destruction spectroscopy, and optionally, the microscopic analysis including electron microscopy (TEM or SEM). The step of performing spectroscopic or microscopic analysis of at least a portion of the ablated portion may be referred to herein as the analysis step. The step of performing spectroscopic or microscopic analysis of at least a portion of the ablated portion may include directing an imaging beam along a trajectory in the apparatus to the ablated portion. During the step of performing spectroscopic or microscopic analysis, the imaging beam may intersect the ablated portion at an imaging position in the trajectory of the imaging beam. Optionally, the imaging beam may include a UV beam, an X-ray beam, an electron beam, an ion beam, and / or a laser beam. The plane of the ablated sample surface, and therefore the plane of the ablated portion of the sample surface, is referred to herein as the sampling plane. The angle between the imaging beam and the sampling plane during the analysis step may be a non-zero angle. The non-zero angle may be between 5 and 175 degrees. The angle between the imaging beam and the sampling plane during the analysis step may be the same as the angle between the laser beam and the sampling plane during the sample ablation step.

[0030] The method further comprises the steps of performing a spectroscopic or microscopic analysis, followed by one or more further cycles of ablation and analysis, each cycle including the steps of ablating further material from a portion of the sample surface, followed by performing a spectroscopic or microscopic analysis of at least a portion of the further ablated portion, and after performing one or more further cycles, determining the depth profile of at least a portion of the composition of the ablated portion of the sample surface, wherein the depth profile is optionally quantitative.

[0031] Following the step of measuring the intensity profile, the method may further include (i) positioning the sample and / or profiling elements, and / or (ii) redirecting the laser beam, such that a portion of the sample surface intersects the laser beam at a reference position during the step of ablating the material from a portion of the sample surface.

[0032] According to one embodiment, both the sample and the profiling element may be placed on the sample stage during the step of measuring the intensity profile. According to such an embodiment, the method may further include (i) moving the sample stage to move the sample and the profiling element relative to a reference position, and / or (ii) changing the direction of the laser beam to move the reference position relative to the sample and the profiling element, during the step of ablating at least a portion of the sample surface after the step of measuring the intensity profile, such that a portion of the sample surface intersects with the laser beam at the reference position.

[0033] The step of shaping the laser beam may include shaping the laser beam to achieve a substantially top-hat or flat-top intensity profile at a reference position. A top-hat intensity profile has a substantially uniform intensity profile across the beam width. Achieving such a top-hat intensity profile is advantageous for accurate and efficient depth profiling while also ensuring that the laser beam has sufficient flux for ablation of the sample.

[0034] The steps of constructing a laser beam may include controlling one or more optical elements configured to shape the laser beam. These one or more optical elements may include diffractive and / or refractive elements. In particular, a beam shaper comprising one or more optical elements that may be diffractive and / or refractive elements may be configured to shape the laser beam. The steps of constructing a laser beam may include controlling the beam shaper. The steps of constructing a laser beam may also include controlling the positioning and / or tilt of the beam shaper.

[0035] Optionally, the method may include aligning the imaging beam and the laser beam relative to each other such that the imaging position coincides with a reference position. Coincidence, as used herein, refers to a spatial coincidence such that there is at least some overlap between them. Coincidence between the imaging beam and the laser beam does not require that the laser beam has the same spatial range as the imaging beam at the coincidence point. The beamwidth of the imaging beam at the imaging position may be smaller than the beamwidth of the laser beam at the reference position. The ratio of the beamwidth of the imaging beam at the imaging position to the beamwidth of the laser beam at the reference position may be, for example, at least 3:1, preferably at least 4:1, and more preferably at least 5:1. Such a ratio is advantageous for improving the quality of the depth profile generated by the ablation and analysis steps.

[0036] The step of aligning the imaging beam and the laser beam may include detecting the illumination of the profiling element by the imaging beam and / or the illumination of the profiling element by the laser beam. Optionally, during the step of aligning the imaging beam and the laser beam, the profiling element intersects the laser beam at a reference position and intersects the imaging beam at an imaging position. The step of aligning the imaging beam and the laser beam may include detecting the illumination area of ​​the profiling element by the imaging beam and detecting the illumination area of ​​the profiling element by the laser beam. Based on the detected areas of illumination of the profiling element by the laser beam and the detected areas of illumination of the profiling element by the imaging beam, the directions of the imaging beam and / or the laser beam may be adjusted. The directions of the imaging beam and / or the laser beam may be adjusted so that the illumination area of ​​the profiling element by the laser beam at least overlaps, preferably completely overlaps, and preferably is centered with the illumination area of ​​the profiling element by the imaging beam.

[0037] In such embodiments where the imaging beam and the laser beam are aligned with each other, the profiling element may include a laser-sensitive material or a laser sensor. If the profiling element includes a laser-sensitive material, the laser-sensitive material may be configured to undergo changes or produce radiation in response to irradiation by the imaging beam and to undergo changes or produce radiation in response to irradiation by the laser beam. The laser-sensitive material may optionally be coated onto the sensor device as discussed above. If the profiling element alternatively includes a laser sensor, the laser sensor may be configured to both detect irradiation by the laser beam and detect irradiation by the imaging beam.

[0038] Optionally, the spectroscopic or microscopic apparatus may include a vacuum chamber. The trajectory of the laser beam may be such that the reference position is located in a position within the vacuum chamber during the steps of measuring the intensity profile of the laser beam at a reference position in the spectroscopic or microscopic apparatus and constructing the shape of the laser beam based on the measured intensity profile.

[0039] As discussed above, the method may further include the steps of ablating a portion of the material from a portion of the sample surface by irradiating a portion of it with a laser beam, and performing spectroscopic analysis of at least a portion of the ablated portion. The trajectory of the laser beam may be such that the reference position is located in a vacuum chamber during the steps of ablating a portion of the material from a portion of the sample surface by irradiating a portion of it with a laser beam, and performing spectroscopic analysis of at least a portion of the ablated portion.

[0040] The method may further include optionally moving the profiling element into a vacuum chamber via a load lock before the step of measuring the intensity profile is performed, and moving the profiling element out of the vacuum chamber after the step of measuring the intensity profile is performed. Thus, in some embodiments, the profiling element may optionally be located only inside the vacuum chamber during the step of measuring the intensity profile of the laser beam. This may be advantageous in embodiments in which the profiling element includes a laser sensor or sensor device to reduce overheating of the profiling element.

[0041] The laser beam used may be a pulsed laser beam. The laser beam may contain one or more pulses having a duration of 1 ns or less, 1 ps or less, or 1 fs or less, with the duration being in the range of 1 ps to 1 fs, which can be selected as desired.

[0042] The laser beam may be an IR laser beam, a visible laser beam, or a UV laser beam.

[0043] A spectroscopic or microscopic apparatus is provided, comprising: a laser beam assembly configured to generate and direct a laser beam along a trajectory through the apparatus; and a laser beam profiler configured to measure the intensity profile of the laser beam at a reference position in the trajectory. The laser beam assembly comprises a beam shaper configured to shape the laser beam based on the measured intensity profile.

[0044] Any features or advantages described in relation to the methods herein can be equally applied to the apparatus.

[0045] The reference position may be at a fixed distance from the focal point of the laser beam, which is referred to herein as the reference distance RD. The reference distance may be zero. Preferably, the reference distance is a non-zero distance such that the reference position is separated from the focal point of the laser beam. The reference position may be upstream of the focal point of the laser beam. The reference distance may be, for example, 0.01 to 100 mm from the focal point of the laser beam, preferably 0.1 to 10 mm, and more preferably 1 to 5 mm. The apparatus may include an objective lens configured to focus the laser beam. The focal point of the laser beam may be defined as the focal length from the objective lens. The reference distance may be, for example, in the range of 0.01% to 5% of the focal length, preferably 0.1% to 5%, and more preferably 0.5% to 2.5% of the focal length. The reference distance may be predetermined. The reference distance may be selected by the user.

[0046] The laser beam may be configured to operate in ablation mode to ablate material from a portion of the sample surface. The laser beam may also be configured to operate in profile mode while measuring the intensity profile of the laser beam. The energy of the laser beam when operating in profile mode may be lower than the energy of the laser beam when operating in ablation mode.

[0047] A laser beam profiler may include a profiling element. As discussed above, the profiling element may include or be composed of a laser-sensitive material. The laser-sensitive material may be configured to be subject to change and / or to generate radiation in response to irradiation by a laser beam.

[0048] Changes in a laser-sensitive material or radiation emitted from it during irradiation with a laser beam can correlate with the intensity of the irradiating laser beam. This allows the intensity profile of the laser beam irradiating the laser-sensitive material to be determined based on changes in the laser-sensitive material or radiation emitted from it. The intensity of radiation from the laser-sensitive material can be proportional to the intensity of the irradiating laser beam.

[0049] A laser beam profiler may include both a laser-sensitive material and a sensor device. The sensor device may or may not form part of the profiling element of the laser beam profiler. The sensor device may be configured to detect changes in the laser-sensitive material or radiation from the laser-sensitive material. The sensor device may include one or more cameras. The laser-sensitive material may be coated onto the sensor device, in which case the profiling element may include the laser-sensitive material coated onto the sensor device and may optionally consist of the laser-sensitive material. Alternatively, the sensor device may be located within the apparatus but remote from the laser-sensitive material, in which case the sensor device may or may not form part of the profiling element of the laser beam profiler. The sensor device may be positioned to receive radiation generated by the laser-sensitive material and / or to image the laser-sensitive material in order to detect changes in the laser-sensitive material. The laser-sensitive material and / or the sensor device may be suitable for ultra-high vacuum (UHV) conditions. Typically, sample ablation is performed under vacuum conditions and may be performed under ultra-high vacuum conditions. By employing profiling elements suitable for ultra-high vacuum conditions, it becomes possible to measure the intensity profile of a laser beam using profiling elements under vacuum conditions, and therefore in the field.

[0050] If the profiling element includes a laser-sensitive material, the laser beam profiler may include a reflector configured to reflect the image of the laser-sensitive material or radiation from the laser-sensitive material. If the laser beam profiler includes a sensor device located at a distance from the laser-sensitive material, the reflector may be configured to reflect the image of the laser-sensitive material or radiation from the laser-sensitive material toward the sensor device.

[0051] Laser-sensitive materials may include light-emitting materials configured to emit photons in response to irradiation with a laser beam. The light-emitting material may be phosphorescent or fluorescent. Optionally, the light-emitting material may be an upshift anti-Stokes phosphor for converting infrared laser light into visible light.

[0052] The profiling element may include a laser sensor. The profiling element may consist of a laser sensor. If the profiling element includes or consists of a laser sensor, the laser sensor may be configured to measure the intensity of the laser beam illuminating it. The laser sensor may include one or more cameras. The laser sensor may be suitable for ultra-high vacuum (UHV) conditions. By employing a laser sensor suitable for ultra-high vacuum conditions, this allows the intensity profile of the laser beam under vacuum conditions, and therefore in the field, to be measured by the laser sensor.

[0053] The apparatus may further include a sample stage configured to support a sample. The sample stage may also be optionally configured to support profiling elements simultaneously or separately.

[0054] The apparatus may be configured to (i) optionally move the profiling elements and / or the sample by moving the sample stage, and / or (ii) redirect the laser beam, in order to reconfigure the apparatus from a first apparatus configuration in which the profiling elements intersect the laser beam at a reference position to a second configuration in which the sample intersects the laser beam at a reference position. The first apparatus configuration may be referred to herein as the profiling configuration, and the second apparatus configuration may be referred to herein as the sample ablation configuration. The profiling configuration may be employed when the laser beam is configured to operate in profiling mode, and the sample ablation configuration may be employed when the laser beam is configured to operate in ablation mode.

[0055] The sample stage may be configured to absorb or dissipate heat generated by the profiling element when the profiling element is supported by the sample stage. The sample stage may include a heat sink configured to receive heat generated by the profiling element when the profiling element is supported by the sample stage. This is particularly advantageous for embodiments employing a profiling element that includes a sensor device having a laser-sensitive material coated thereon, or a profiling element that includes a laser sensor, because the laser sensor or sensor device may generate heat during use. Such heat generation can lead to overheating and degradation of the performance of the laser sensor or sensor device, especially when the sensor device or laser sensor is placed in a vacuum chamber while measuring the intensity profile of a laser beam.

[0056] In embodiments where the profiling element includes a laser sensor, the sample stage may then be configured to be electrically and releasably coupled to the laser sensor when the laser sensor is supported on the sample stage. The sample stage may also include an electrically coupled element configured to be electrically and releasably coupled to the laser sensor when the laser sensor is supported on the sample stage. The electrically coupled element may be configured to transmit power to and / or data from the laser sensor. A laser sensor that is powered and / or operating for data transfer only when supported on the sample stage can advantageously reduce heat generation by the laser sensor. Heat generation can lead to overheating and performance degradation of the laser sensor, particularly if the laser sensor is located in a vacuum chamber during use.

[0057] The electrical coupling element may include a wired connection configured to transmit power to and / or data from the laser sensor, and optionally the wired connection includes one or more pairs of twisted wires.

[0058] In one embodiment, the electrically coupled element may be configured to transmit power to the laser sensor, and the device may further include a data connection configured to transmit data from the laser sensor. The data connection may be a wireless data connection. In an alternative embodiment, the electrically coupled element may be configured to transmit both power to and / or data from the laser sensor. For example, a wired connection, which may include one or more pairs of twisted wires, may be configured to transmit both power to and data from the laser sensor.

[0059] In embodiments including a laser-sensitive material coated on a sensor device with a profiling element, the sample stage may then be configured to electrically couple to the sensor device in a releaseable manner when the sensor device is supported on the sample stage. The sample stage may include an electrically coupled element configured to electrically couple to the sensor device in a releaseable manner when the sensor device is supported on the sample stage. The electrically coupled element may be configured to transmit power to and / or data from the sensor device. A sensor device that is powered and / or operating for data transfer only when supported on the sample stage can advantageously reduce heat generation by the sensor device. Heat generation can lead to overheating and performance degradation of the sensor device, particularly when the sensor device is placed in a vacuum chamber during use.

[0060] The electrical coupling element may include a wired connection configured to transmit power to and / or data from a sensor device, and optionally the wired connection includes one or more pairs of twisted wires.

[0061] In one embodiment, the electrically coupled element may be configured to transmit power to a sensor device, and the device may further include a data connection configured to transmit data from the sensor device. The data connection may be a wireless data connection. In an alternative embodiment, the electrically coupled element may be configured to transmit both power to and / or data from the sensor device. For example, a wired connection, which may include one or more pairs of twisted wires, may be configured to transmit both power to and data from the sensor device.

[0062] The apparatus may further include a holder configured to support a profiling element. The holder may be configured to be mechanically coupled to the sample stage in a releasable manner.

[0063] In embodiments where the profiling element includes a laser sensor, the sample stage may then be configured to be electrically and releasably coupled to the laser sensor via the holder when the holder is mechanically coupled to the sample stage. In embodiments where the profiling element includes a laser-sensitive material coated on the sensor device, the sample stage may then be configured to be electrically and releasably coupled to the sensor device via the holder when the holder is mechanically coupled to the sample stage.

[0064] In embodiments where the profiling element includes a laser sensor, the electrical coupling element may be a stage electrical coupling element, and the holder may comprise a holder electrical coupling element electrically connected to the laser sensor. The holder electrical coupling element may be configured to be electrically releasably coupled to the stage electrical coupling element when the holder is mechanically coupled to the sample stage.

[0065] The holder electrical coupling element and the stage electrical coupling element may be configured to transmit power to and / or data from the laser sensor when the holder is mechanically coupled to the sample stage. The stage electrical coupling element may include one or more stage electrical contacts, and the holder electrical coupling element may include one or more holder electrical contacts. The stage electrical contacts may be configured to make direct contact with the holder electrical contacts when the holder is mechanically coupled to the sample stage.

[0066] The holder electrical coupling element may include a wired connection configured to transmit power and / or data to the laser sensor. The wired connection may include one or more pairs of twisted wires.

[0067] In embodiments where the profiling element includes a sensor device, the electrical coupling element may be a stage electrical coupling element, and the holder may comprise a holder electrical coupling element electrically connected to the sensor device. The holder electrical coupling element may be configured to be electrically releasably coupled to the stage electrical coupling element when the holder is mechanically coupled to the sample stage. The holder electrical coupling element and the stage electrical coupling element may be configured to transmit power to and / or data from the sensor device when the holder is mechanically coupled to the sample stage.

[0068] The stage electrical coupling element may include one or more stage electrical contacts, and the holder electrical coupling element may include one or more holder electrical contacts. The stage electrical contacts may be configured to directly contact the holder electrical contacts when the holder is mechanically coupled to the sample stage.

[0069] The holder electrical coupling element may include a wired connection configured to transmit power and / or data to the sensor device. The wired connection may include one or more pairs of twisted wires.

[0070] The apparatus may further include a processing device configured to receive data from a laser sensor or sensor device via an electrically coupled element and / or a data connection.

[0071] The apparatus may further include a vacuum chamber. The laser beam assembly may be configured to direct the laser beam such that the reference position is located within the vacuum chamber.

[0072] The sample stage can be mounted inside the vacuum chamber.

[0073] The laser beam assembly may be positioned outside the vacuum chamber, which has a window configured to allow the laser beam to pass through.

[0074] The apparatus may optionally include a transfer component for moving the profiling element in and out of the vacuum chamber via a load lock. Thus, the profiling element may be located inside the vacuum chamber during intensity profile measurement and then removed from the vacuum chamber after intensity profile measurement. Minimizing the time the profiling element is inside the vacuum chamber may be advantageous in reducing heat generation by the profiling element in embodiments where the profiling element includes a sensor device having a laser sensor or a laser-sensitive material coated thereon.

[0075] In embodiments employing a holder, the transfer component may optionally be configured to move the holder in and out of the vacuum chamber via a load lock.

[0076] The apparatus may further comprise an imaging beam assembly configured to generate and direct an imaging beam along a trajectory within the apparatus, wherein the imaging beam is optionally one or more of a UV beam, an electron beam, an ion beam, an X-ray beam, and / or a laser beam.

[0077] In embodiments employing a profiling element that includes a laser-sensitive material, the laser-sensitive material may be configured to undergo changes or generate radiation in response to irradiation by an imaging beam. Such a laser-sensitive material may be employed for both detecting irradiation by a laser beam and detecting irradiation by an imaging beam to enable alignment of the imaging beam and the laser beam. The laser-sensitive material may be optionally coated onto the sensor device as discussed above. If the profiling element alternatively includes a laser sensor, the laser sensor may be configured to both detect irradiation by a laser beam and detect irradiation by an imaging beam to enable alignment of the imaging beam and the laser beam. Herein, embodiments of the present disclosure will be described by reference to the following non-limiting drawings, merely as examples. schematic cross-section [Brief explanation of the drawing]

[0078] [Figure 1] This is a schematic diagram of an exemplary embodiment of the apparatus according to the present invention. [Figure 2] This is a schematic diagram illustrating an optical setup that may be employed in the apparatus and method of the present invention for generating, shaping, and directing a laser beam. [Figure 3] This is a schematic diagram illustrating an optical setup that may be employed in the apparatus and methods of the present invention to generate, shape, and direct a laser beam having a top-hat or flat-top beam intensity profile. [Figure 4] Figure 1 is a schematic cross-sectional view of a portion of the apparatus demonstrating the use of a beam profiler that may be employed in exemplary embodiments of the present invention, the beam profiler comprising a profiling element which is a laser-sensitive material. [Figure 5A] Figure 4 is a schematic cross-sectional view of a profiling element that can be used in a beam profiler, where both the profiling element and the sample are placed on the sample stage of the instrument. [Figure 5B]Figure 4 is a schematic perspective view of profiling elements that can be used in the beam profiler, with the profiling elements arranged on the sample holder. [Figure 6] Figure 1 is a schematic cross-sectional view of a portion of the apparatus demonstrating the use of a beam profiler that may be employed in exemplary embodiments of the present invention, the beam profiler including a profiling element which is a laser sensor. [Figure 7] Figure 1 is a schematic cross-sectional view of a portion of the apparatus demonstrating the use of a beam profiler that may be employed in exemplary embodiments of the present invention, the beam profiler comprising a profiling element which is a laser-sensitive material coated on a sensor device. [Figure 8A] Figure 6 is a schematic perspective view of the laser sensor positioned on the sensor holder of the device. [Figure 8B] Figure 7 is a schematic perspective view of the sensor device, which has a laser-sensitive material coated thereon and is positioned on the sensor holder of the device. [Figure 8C] This is a schematic cross-sectional view of the sensor holder shown in Figure 8A or Figure 8B, which is mechanically coupled to the sample stage of the apparatus and electrically coupled to the power supply and processing devices of the apparatus via the sample stage. [Figure 9] This is an exemplary embodiment of the method of the present invention. [Figure 10] Figure 9 shows an exemplary embodiment of the method. [Figure 11] Figure 9 shows an exemplary embodiment of the method. [Figure 12] This is a schematic diagram of the implementation of steps 201-206 of the method in Figure 10, using the apparatus in Figure 1. [Figure 13] This is a schematic diagram of the implementation of steps 301-306 of the method shown in Figure 11, using the apparatus shown in Figure 1. [Figures 14A-14E]Figure 14A is an illustrative representation demonstrating the evolution of craters formed by repeated sample ablation of a sample performed using a laser beam, where the laser beam has a Gaussian intensity profile at the reference position and the sample surface intersects with the laser beam at the reference position during ablation. Figures 14B and 14C are illustrative representations of depth profiles that can be generated after repeated cycles of sample ablation and spectroscopic or microscopic analysis of the ablated portion using a laser beam and an imaging beam. The laser beam has a Gaussian intensity profile at the reference position, where the sample surface intersects with the laser beam at the reference position during ablation and with the imaging beam at the imaging position during analysis. The ratio of the beamwidth of the laser beam at the reference position to the beamwidth of the imaging beam at the imaging position, adopted to obtain Figure 14B, was 5:1, and the ratio adopted to obtain Figure 14C was 2:1. Figure 14D is an illustrative representation demonstrating the evolution of craters formed by repeated sample ablation performed using a laser beam, where the laser beam has a perfect top-hat intensity profile at the reference position, and the sample surface intersects with the laser beam at the reference position during ablation. Figure 14E is an illustrative representation of the depth profiles that may be generated after repeated cycles of sample ablation and spectroscopic or microscopic analysis of the ablated portion using a laser beam and an imaging beam. Laser beam with a top-hat intensity profile at the reference position. [Figures 15A-15D]Figures 15A–15C demonstrate the generation of intensity profiles using a beam profiler that includes a beam profiling element, which is a laser-sensitive material. The laser-sensitive material intersected the laser beam at a reference position while the intensity profile was being measured. The laser-sensitive material is a phosphorescent material that fluoresces in response to irradiation with a laser beam. The intensity profile was obtained using the arrangement shown in Figure 4. Figure 15A is a raw image of the laser-sensitive material fluorescing due to irradiation with a laser beam. Figures 15B and 15C are digitally magnified intensity profiles of the laser beam in the form of heatmaps, generated by processing the raw image of Figure 15A. Camera exposure was adjusted for Figure 15C compared to Figure 15B. Figure 15D is the intensity profile of the same laser beam used in Figures 15B and 15C. The intensity profile is represented as a heatmap. The intensity profile was generated using a profiling camera that intersected the laser beam at a reference position. The profiling camera was not under vacuum conditions. [Figures 16A-16E]Figures 16A and 16D demonstrate the generation of a laser beam intensity profile using a beam profiler that includes a beam profiling element made of a laser-sensitive material. The laser-sensitive material intersected the laser beam at a reference position while the intensity profile was being measured. The laser-sensitive material is a phosphorescent material that fluoresces in response to irradiation with the laser beam. The intensity profile was obtained under vacuum conditions using the arrangement shown in Figure 4. Figures 16A and 16C are initial raw images showing the laser-sensitive material fluorescing due to irradiation with the laser beam. Figures 16B and 16D are the laser beam intensity profiles represented as heatmaps. Figure 16B was generated by processing the raw image of Figure 16A, and Figure 16D was generated by processing the raw image of Figure 16C. The optical elements used to shape the laser beam were adjusted for Figure 16C compared to Figure 16A to achieve a more accurate flat-top intensity profile at the reference position. When the images shown in Figures 16A and 16C were taken, the incident angle between the laser beam and the laser-sensitive material was 45 degrees. Figure 16E shows the intensity profile of the same laser beam used in Figures 16A-16D, where the incident angle between the laser beam and the laser-sensitive material was 90 degrees. The intensity profile is represented as a heat map. The intensity profile was obtained using a profiling camera intersected with the laser beam at a reference position. The profiling camera was not operated under vacuum conditions. [Figures 17A-17B]This study demonstrates the generation of a laser beam intensity profile using a beam profiler that includes a beam profiling element, which is a laser-sensitive material, placed on a sensor holder. The laser sensor intersected the laser beam at a reference position while the intensity profile was being measured. The incident angle between the laser beam and the laser sensor was 43 degrees when the image shown in Figure 17A was taken. The intensity profile was obtained under vacuum conditions using the configuration shown in Figure 8C. Figure 17A is the initial raw image taken by the laser sensor in response to irradiation by the laser beam. Figure 17B is the laser beam intensity profile represented as a heatmap. Figure 17B was generated by processing the raw image in Figure 17A. [Modes for carrying out the invention]

[0079] Figure 1 is a schematic diagram of a spectroscopic or microscopic apparatus 10, referred to herein as apparatus 10. Apparatus 10 may include a controller 100 configured to control the operation of the components of apparatus 10. Apparatus 10 may include a processing device 120 electrically coupled to the controller 100. The processing device 120 may form part of the controller 100. Apparatus 10 may include a vacuum chamber 20 (not shown in Figure 1) configured to receive a sample 110 inside. Apparatus 10 may include a sample stage 70 configured to support the sample 110 on top. The sample stage 70 may be located inside the vacuum chamber 20.

[0080] The apparatus 10 includes a laser beam assembly 40 configured to generate and direct a laser beam along a trajectory within the apparatus 10. Figures 2 and 3 demonstrate an exemplary optical setup of the laser beam assembly 40. Figure 2 also demonstrates an exemplary trajectory of the laser beam, including a reference position 300 and a focal point 320. A controller 100 may be configured to control the positioning of the components of the laser beam assembly 40.

[0081] As best shown in Figure 3, the reference position 300 may be at a reference distance (RD) from the focal point 320 of the laser beam. The focal point 320 is at a known position in the trajectory of the laser beam, based on the arrangement of optical components in the laser beam assembly. The reference distance may be zero, such that the reference position 300 is at the focal point 320 of the laser beam. Preferably, the reference distance is a non-zero distance such that the reference position is spaced away from the focal point 320 of the laser beam. As shown in Figure 2, the reference position 300 may be upstream of the focal point 320 of the laser beam. The term upstream is in the context of a laser beam in normal use (i.e., the laser beam propagates in the direction from upstream to downstream). The reference distance may be, for example, 0.01 to 100 mm from the focal point, preferably from the focal point. The focal point can be 0.1 to 10 mm, more preferably 105 mm from the focal point. The focal point of the laser beam can be defined as the focal distance from the objective lens that is focused when the laser beam is directed along its trajectory through the apparatus. The reference distance can be, for example, in the range of 0.01% to 5% of the focal length, preferably 0.1% to 5%, more preferably 0.5% to 2.5%. The reference distance may be predetermined. The reference distance may be selected by the user. The laser beam assembly 40 may be configured to control the direction of the laser beam and thus control the location of the reference position 300 within the apparatus 10. The laser beam assembly 40 may be configured to direct the laser beam such that the reference position is within the vacuum chamber 20 of the apparatus 10. The vacuum chamber 20 may be an ultra-high vacuum chamber. The ultra-high vacuum chamber may be 1.0 × 10⁻⁶ -8 It has a pressure of less than mbar.

[0082] The laser beam may be a femtosecond, picosecond, or nanosecond laser beam. If the laser beam is a femtosecond laser beam, the laser source 410 may be an fs laser source 410 based on a diode pump Yb medium that can provide a range of pulse length, pulse wavelength, and pulse energy. In an exemplary embodiment, the laser beam may be a femtosecond laser having a wavelength of 1030 nm and a pulse length of 160 fs. Alternatively, the laser wavelength may be 515 nm or 343 nm. Shorter or longer pulses, such as in the range of 10 fs to 10 ps, ​​or even less than 1 fs to 1 ns, may also be used. The beam width of the laser beam at the reference position 300 may be in the range of about 50 to 500 μm, preferably 100 to 300 μm. The pulse repetition rate may vary. In some embodiments, pulse repetition rates on the order of up to about 10 kHz may be used.

[0083] The apparatus 10 includes a laser beam profiler 500 configured to measure the intensity profile of the laser beam at a reference position 300 in the trajectory of the laser beam. The beam profiler 500 will be discussed in more detail below.

[0084] The laser beam assembly 40 may include a laser beam source 410 configured to generate a laser beam. The laser beam may be generated as a continuous beam or as pulses or bursts of pulses. The laser beam assembly 40 may include one or more optical components configured to shape and direct the laser beam, as shown in Figure 2. In particular, the laser beam assembly 40 may include a beam shaper 420 configured to shape the laser beam. The reference position 300 may be located downstream of the beam shaper 420 and upstream of the focal point 320, as shown in Figure 2. Thus, the reference position may be defined as a fixed distance from the beam shaper 420 that can be predetermined. In particular, the reference position may be located in the imaging plane of the beam shaper 420.

[0085] The controller 100 and / or processing device 120 may be configured to receive the intensity profile generated by the beam profiler 500 and determine and control adjustments to the positioning of the beam shaper 420 based on the measured intensity profile to achieve a desired intensity profile at a reference position. The beam shaper 420 may include one or more optical elements configured to shape the laser beam based on the intensity profile measured by the beam profiler 500. The controller 100 and / or processing device 120 may be configured to receive the intensity profile generated by the beam profiler 500 and determine and control adjustments to the positioning of one or more optical elements of the beam shaper 420 based on the measured intensity profile to achieve a desired intensity profile at a reference position. In the exemplary embodiments shown in Figures 2 and 3, the beam shaper 420 includes diffractive optical elements (DOEs) configured to shape the laser beam. The desired intensity profile is optionally a top-hat intensity profile (a uniform intensity spot of any shape, such as rectangular, square, circular, or other), as shown in Figure 2. Diffractive optical elements may be referred to herein as top-hat or flat-top beam shapers and may be configured to substantially convert a Gaussian incident laser beam into a top-hat intensity profile, as shown in Figure 2. The beam shaper 420 may be configured to shape the laser beam based on a measured intensity profile in order to achieve a top-hat intensity profile at a reference position 300. For example, the controller 100 and / or processing device 120 may be configured to determine and control one or more optical elements of the beam shaper 420 based on a measured intensity profile in order to achieve a top-hat intensity profile at a reference position 300. In particular, the controller 100 may be configured to control the direction of laser beam propagation and / or the translation of the beam shaper in a direction perpendicular to the angular rotation and / or tilt of the beam shaper 420, based on a measured intensity profile.

[0086] The laser beam assembly 40 may include a beam shaper positioning mechanism (not shown) configured to adjust the position of the beam shaper 420, more specifically, the position of the optical elements of the beam shaper 420, in a direction perpendicular to the direction of laser beam propagation. The laser beam assembly 40 may also include a beam shaper tilting mechanism (not shown) configured to tilt the position of the beam shaper 420, more specifically, the position of the optical elements of the beam shaper 420. The controller 100 and / or processing device 120 may be configured to determine and control the beam shaper positioning mechanism and / or beam shaper tilting mechanism based on a measured intensity profile in order to achieve a top-hat intensity profile at a reference position 300.

[0087] The laser beam assembly 40 may include an objective lens 450 downstream of the beam shaper 420. The controller 100 may be configured to control the positioning of the objective lens 450. The position of the objective lens may be adjusted to adjust the direction of the laser beam, and therefore the location of the reference position 300 in the apparatus 10. Alternatively, the positioning of the objective lens 450 may be controlled manually by the user.

[0088] In the exemplary embodiments shown in Figures 2 and 3, the laser beam may first pass through a variable beam expander 415 to increase the beam cross-sectional area. The incident laser beam has a Gaussian shape (TEM). 00 ) may have a nominal 1 / e required by the beam shaper 420 using the variable beam expander 415. 2 The diameter is sized and collimated. The Gaussian intensity profile is then converted by the beam shaper 420 into a top-hat intensity profile (a uniform intensity spot in the shape of a circle, square, or rectangle).

[0089] As shown in Figure 2, the laser beam assembly 40 may optionally include further optical components configured to direct and focus the laser beam. The laser beam assembly 40 may include a mirror 425 downstream of the beam shaper 420 that directs the laser beam to a variable attenuator 430 and a polarization adjustment optical system 435. If necessary, the variable attenuator 430 may be used to reduce beam power / energy. The polarization adjustment optical system 435 may consist of a zero-order half-wave plate or a zero-order quarter-wave plate and may be rotatable. A second beam expander 440 may be positioned before the mirror 445 to adjust the spot size of the beam at the focal point 320. The mirror 445 directs the laser beam through a focusing lens 450 that focuses the laser beam to the desired spot size. The laser beam may pass through a window 25, such as a glass window, configured to allow the laser beam to pass through to the vacuum chamber 20.

[0090] The controller 100 may be configured to control the laser beam assembly 40 to operate in either profiling mode or ablation mode. Profiling mode may be employed while the intensity profile of the laser beam is being measured. Ablation mode may be employed while the sample is being ablated by the laser. The beamwidth of the laser beam at the reference position may be the same in both profiling mode and ablation mode. The energy of the laser beam at the reference position in profiling mode may be different from, and preferably lower than, the energy of the laser beam in ablation mode. The laser beam generated by the laser beam assembly 40 may be configured to ablate the sample 110 when operating in ablation mode. During sample ablation, a portion of the sample surface may intersect with the laser beam at the reference position. The portion of the sample surface may be the target area of ​​the sample. The plane of the sample surface that intersects with the laser beam at the reference position during ablation may be referred to herein as the sampling plane. The laser beam may intersect with the sampling plane at a non-zero angle during sample ablation. The angle of incidence between the laser beam and the sampling plane during sample ablation may be the same as the angle of incidence between the laser beam and the profiling plane when the intensity of the laser beam profile is being measured. The sampling plane may be parallel to the profiling plane.

[0091] The energy of the laser beam in profiling mode at reference position 300 may be lower than the energy required to ablate the profiling element 510 and / or sample 110; for example, the energy of the laser beam in profiling mode may be less than 100 μJ. The energy of the laser beam in ablation mode may be sufficient to ablate the sample 110 and may be higher than the energy of the laser beam in profiling mode. The energy of the laser beam in ablation mode may vary depending on the required material and ablation capacity, such as 10 nJ to 2000 μJ, or more preferably 50 to 1000 μJ.

[0092] The controller 100 may be configured to receive input from the user to set the laser beam parameters when operating in ablation mode so that the energy provided at the reference position 300 is sufficient for sample ablation. For example, the controller 100 may be configured to control the pulse energy and / or pulse duration so that the energy provided at the reference position 300 exceeds the ablation threshold of the sample material but falls below the energy or duration sufficient to cause damage to the remaining surface chemical properties. The controller 100 may receive input from a user interface or from another computer. The input may include settings for adjusting one or more of the pulse energy, pulse duration, pulse repetition frequency, and wavelength. Alternatively, the input may provide an indication of the expected material or type of material. The controller may include, for example, algorithms, lookup tables, libraries, or databases in the execution of a computer program on the controller's processing device, to provide laser parameters optimized to ablate the surface while avoiding or minimizing damage to the underlying chemical composition for the expected material or type of material of the sample. The parameters may be further optimized to provide rapid ablation while minimizing damage to the underlying chemical composition.

[0093] The controller 100 may be configured to set the laser beam parameters when operating in ablation mode, based on a survey scan of the sample surface to be ablated, so that the energy provided at the reference position 300 is sufficient for sample ablation. The survey scan may include performing electron spectroscopy such as XPS or AES. Other sample survey scanning techniques may also be used. In one example, for a single-layer sample, the survey scan may determine the elemental composition within the surface layer. A library of similar materials may then be used to optimize settings such as fluence, frequency, pulse duration, and wavelength to achieve a desired ablation rate (i.e., level or nm per pulse) in which the chemical information within the surface layer is preserved. The number of pulses may also then be set for a desired depth or level of the profile. Crater morphology, such as size, shape, and / or surface roughness or variation, may also be considered. For multilayer samples, the approach for a single layer may be repeated for each layer. Alternatively, for multilayer samples, either prior knowledge of the layer-by-layer composition or a survey profile can be used to determine the laser parameters to use. For example, the survey profile may involve an approximate assessment of the composition, followed by optimizing the settings using a library of similar materials, similar to the case of a single layer. If the library is insufficient or inaccurate for the sample, the ablation rate can be determined by in-house analysis of the craters formed at various fluences and pulse / level numbers (e.g., mechanical profilometry, microscopy, or white light interferometry).

[0094] The apparatus 10 may include an imaging beam assembly 50 configured to generate and direct an imaging beam along a trajectory within the apparatus 10. The imaging beam may be referred to as an excitation beam. The imaging beam may be one or more of a UV beam, an electron beam, an ion beam, an X-ray beam, and / or a laser beam. The apparatus 10 may further include an analyzer 80 and / or a detector 90 configured to detect electrons, ions, and / or photons generated by the incidence of the imaging beam on the sample surface. The imaging beam assembly 50 may include an imaging beam source. The generation and direction of the imaging beam may be controlled by a controller 100.

[0095] The laser beam assembly 40 and the imaging beam assembly 50 may be configured to direct the laser beam and the imaging beam, respectively, to the same target area. By operating the laser beam assembly 40 alternately to induce ablation of a portion of the sample surface and then irradiating with the imaging beam to irradiate at least a portion of the ablated portion of the sample, a compositional depth profile of the sample can be constructed. According to such an arrangement, the imaging beam may optionally be centered at the center of the crater formed by the ablation. In particular, the imaging beam assembly 50 may be directed so that the ablated portion of the sample intersects with the imaging beam at an imaging position in the trajectory of the imaging beam. The imaging beam may intersect with the sampling plane of the sample. The angle between the imaging beam and the sampling plane may be a non-zero angle. The angle between the imaging beam and the sampling plane during analysis may be the same as the angle between the laser beam and the sampling beam during sample ablation. The imaging position may be a fixed distance from the focal point, which is predetermined and / or selected by the user. The imaging position may be the focal point of the imaging beam. The focal point of the imaging beam is a known parameter of the imaging beam assembly, defined according to the arrangement and setup of the optical and / or electro-optical components within the imaging beam assembly 50.

[0096] Depending on the type of imaging beam, analyzer 80, and detector 90 employed in the apparatus 10, the apparatus 10 may be defined as a spectroscopic or microscopic apparatus. For example, the imaging beam assembly 50, analyzer 80, and detector 90 may be configured for X-ray photoelectron spectroscopy. In such an embodiment, the imaging beam employed is an X-ray beam, and the analyzer 80 and detector 90 are configured to measure the intensity and energy of the emitted photoelectrons. Alternatively, the imaging beam assembly 50, analyzer 80, and detector 90 may be configured for Auger electron spectroscopy. In such an embodiment, the imaging beam employed is an electron beam, and the analyzer 80 and detector 90 are configured to measure the intensity and energy of the emitted Auger electrons. Alternatively, the imaging beam assembly 50, analyzer 80, and detector 90 may be configured for ultraviolet photoelectron spectroscopy. In such an embodiment, the imaging beam employed is a UV beam, and the analyzer 80 and detector 90 are configured to measure the intensity and energy of the emitted photoelectrons. Alternatively, the imaging beam assembly 50, analyzer 80, and detector 90 may be configured for secondary ion mass spectrometry (SIMS). In such embodiments, the imaging beam employed is an ion beam, and the analyzer 80 and detector 90 are configured to measure the intensity and energy of secondary ions. Alternatively, the imaging beam assembly 50, analyzer 80, and detector 90 may be configured for laser-induced breakdown spectroscopy. In such embodiments, the imaging beam employed is a laser beam, and the analyzer 80 and detector 90 are configured to measure the intensity and energy of emitted photons. Alternatively, the imaging beam assembly 50, analyzer 80, and detector 90 may be configured for an electron microscope such as a scanning electron microscope, a transmission electron microscope, or a scanning transmission electron microscope. In such embodiments, the imaging beam employed is an electron beam, and the detector 90 is configured to measure electrons.

[0097] The imaging beam assembly 50 may be configured to perform any combination of the imaging techniques discussed above. For example, the imaging beam assembly 50 may be configured to perform X-ray photoelectron spectroscopy and Auger electron microscopy by employing an X-ray beam and an electron beam.

[0098] The imaging beam assembly 50 may include an imaging beam source configured to generate an imaging beam. The imaging beam may reach the sample surface in the vacuum chamber 20 by passing through a window (not shown) in the vacuum chamber 20 that allows the imaging beam to pass through, such as a glass window.

[0099] In embodiments where the imaging beam is an X-ray beam, the imaging beam source may be an X-ray source configured to produce X-rays. The X-rays may be monochromatic X-rays and may be produced from a high-energy electron gun positioned to accelerate electrons toward a target anode. The target anode may be aluminum so that the resulting X-rays are produced at an appropriate energy. The X-rays may be directed toward the vacuum chamber 20 via a monochromator crystal.

[0100] The emission of electrons from the sample surface during analysis can accumulate positive charge on the sample. Considering this, the apparatus 10 may further include a flood gun configured to provide charge neutralization at the sample surface during analysis. This is most serious when the sample surface is insulated, as the charge accumulation remains on the surface and is not dissipated by charge transport through the sample. Positive charge can affect the XPS spectrum, for example, by shifting peaks to higher binding energies and causing distortion. The flood gun may be any preferred type, such as those disclosed in GB2411763A. The flood gun neutralizes the charge on the sample surface by replenishing emitted electrons. Neutralization stabilizes and controls the charge on the sample surface.

[0101] As discussed above, the apparatus 10 includes a beam profiler 500 configured to measure the intensity profile of a laser beam at a reference position 300. The beam profiler 500 may be configured to measure the 2D intensity profile of a laser beam at the reference position 300. More specifically, the beam profiler 500 may be configured to measure the intensity profile of a laser beam at the reference position 300 in a profiling plane.

[0102] The beam profiler 500 may include a profiling element 510. The profiling element 510 may intersect with the laser beam at a reference position 300 while the intensity profile is being measured. In other words, while the intensity profile of the laser beam is being measured, the profiling element 510 may intersect with the laser beam at a reference position 300. During the step of measuring the intensity profile of the laser beam, the laser beam may be incident on the surface of the profiling element 510 at a non-zero angle. During the step of measuring the intensity profile of the laser beam, at least a portion of the surface of the profiling element 510 may be overlapped by the laser beam. The surface area of ​​the profiling element 510 in the profiling plane may be larger than the area of ​​the laser beam spot size at the reference position 300. Alternatively, the area of ​​the profiling element in the profiling plane may be smaller than the beam width of the laser beam at the reference position, and the profiling element may be translated across the area of ​​the laser beam spot at the reference position so as to scan across the laser beam spot at the reference position.

[0103] Therefore, the apparatus 10 may be configured in a first configuration or a second configuration, the first configuration being used while the intensity of the laser beam is being measured, and the second configuration being used while sample ablation is being performed. The first configuration may be called a profiling configuration, and the second configuration may be called a sample ablation configuration. In the profiling configuration, the profiling element 510 intersects with the laser beam at a reference position 300. In the sample ablation configuration, the surface of the sample 110 intersects with the laser beam at a reference position 300. During spectroscopic or microscopic analysis of the ablated portion of the sample, the apparatus may be configured in a third configuration, which may be called an analysis configuration, where the ablated portion of the sample 110 intersects with the imaging beam at the imaging position. The sample 110 may be in the same location within the apparatus 10 for both the sample ablation configuration and the analysis configuration. In such an arrangement, the imaging beam and the laser beam may be aligned with each other. In such an arrangement, the imaging beam and the laser beam may coincide. Alternatively, the sample 110 may be located in a different location within the apparatus 10 for the analysis configuration compared to the sample ablation configuration. In such an arrangement, the imaging beam and the laser beam would not be aligned with each other.

[0104] The profiling element 510 may include a laser-sensitive material 520 or a laser sensor 530. The profiling element 510 may consist of a laser-sensitive material 520, as shown in Figure 4, or the profiling element 510 may consist of a laser sensor 530, as shown in Figure 6. The profiling element 510 may be placed inside the vacuum chamber 20 while the intensity profile of the laser beam is being measured. The profiling element 510 may be supported on the sample stage 70 while the intensity profile of the laser beam is being measured. The laser-sensitive material 520 may be configured to undergo detectable changes and / or to produce radiation in response to irradiation by the laser beam. If the profiling element 510 includes a laser-sensitive material 520 configured to undergo detectable changes and / or to produce radiation in response to irradiation by the laser beam, the beam profiler 500 may also include a sensor device 521 configured to detect changes in the laser-sensitive material 520 or radiation from the laser-sensitive material 520. The sensor device 521 may be configured to process detected changes in the laser-sensitive material 520 or radiation from the laser-sensitive material 520 to generate an intensity profile of the laser beam. The laser sensor 530 may be configured to process the detected intensity of the laser beam to generate an intensity profile of the laser beam. The processing device 120 may be configured to receive the intensity profile of the laser beam from the laser sensor 530 or the sensor device 521. Alternatively, the processing device 120 may be configured to receive raw data from the laser sensor 530 and / or the sensor device 521 and process the raw data to generate an intensity profile.

[0105] As discussed above, the laser-sensitive material 520 may be configured to undergo a detectable change and / or to generate radiation in response to irradiation by a laser beam. The detectable change and / or generated radiation may correlate with the intensity of the laser beam irradiating the laser-sensitive material 520. In particular, the generated radiation may have an intensity proportional to the intensity of the laser beam irradiating the laser-sensitive material 520. The laser-sensitive material 520 may intersect with the laser beam at a reference position 300 when the apparatus 10 is in a profiling configuration (i.e., while the intensity profile of the laser beam is being measured). The laser beam may be directed such that the reference position 300 is located inside the vacuum chamber 20 as discussed above, and therefore, as shown in Figures 4 and 7, the laser-sensitive material 520 may also be located inside the vacuum chamber 20 when the apparatus is in a profiling configuration. Thus, the laser-sensitive material 520 can be used to measure the intensity profile of a laser beam in situ. The vacuum chamber may be an ultra-high vacuum chamber, and the laser-sensitive material 520 may be suitable for ultra-high vacuum (UHV) conditions. Suitable means that the laser-sensitive material 520 does not degrade significantly or emit gas when in a vacuum chamber under UHV conditions.

[0106] As discussed above and illustrated in the embodiments shown in Figures 4 and 7, the beam profiler 500 may include a sensor device 521 in addition to the laser-sensitive material 520. The sensor device 521 may be configured to detect changes in the laser-sensitive material 520 or radiation from the laser-sensitive material 520. The sensor device 521 may be a camera, for example, a CCD camera or a CMOS camera. The laser-sensitive material 520 may be coated onto the sensor device 521. In such embodiments, the sensor device 521 and the laser-sensitive material 520 coated thereon will together form a profiling element 510. Alternatively, the sensor device 521 may be remote from the laser-sensitive material 520 and may not be considered to form part of the profiling element 510. In such embodiments, the profiling element may consist of the laser-sensitive material 520.

[0107] The laser-sensitive material 520 may include a light-emitting material configured to emit photons in response to irradiation with a laser beam. In particular, the laser-sensitive material 520 may include a phosphorescent and / or fluorescent material. The laser-sensitive material 520 may include a phosphor that is an upshift phosphor. An upshift phosphor converts photons absorbed from the laser beam into photons of shorter wavelengths. Alternatively, the laser-sensitive material 520 may include a phosphor that is a downshift phosphor. A downshift phosphor converts absorbed photons from the laser beam into photons of longer wavelengths. The laser-sensitive material may include a phosphor configured to convert laser beam irradiation into visible light. For example, the laser-sensitive material may include an upshift anti-Stokes phosphor, and optionally the laser beam may be an IR laser beam. The upshift phosphor may absorb IR photons and emit photons in the visible range. As a further example, the laser beam may be a UV laser beam, and the laser-sensitive material 520 may include a downshift phosphor that can be configured to absorb UV photons from the UV laser beam and emit photons in the visible range.

[0108] In one embodiment, the laser-sensitive material 520 may be configured to emit photons at an intensity proportional to the intensity of the laser beam irradiating it. The sensor device 521 may be configured to detect the intensity of photons emitted from a beam profiling element in a profiling plane. The sensor device 521 and / or a processing device 120 that may be connected to the sensor device 521 may be configured to generate an image of the laser beam intensity distribution based on the proportional relationship between the intensity of photons emitted from the laser-sensitive material 520 and the intensity of the laser beam irradiating the laser-sensitive material 520. In such embodiments, the sensor device 521 may be one or more cameras, such as a CCD camera or a CMOS camera.

[0109] In embodiments employing a laser-sensitive material that generates radiation in response to irradiation by a laser beam, the sensor device 521 may be positioned inside or outside the vacuum chamber when the apparatus 10 is in a profiling configuration (i.e., while the intensity profile of the laser beam is being measured). The sensor device 521 may include a sensing surface 521a, which may be positioned so that the sensing surface 521a receives radiation from the laser-sensitive material 520.

[0110] In particularly advantageous embodiments, such as the embodiment shown in Figure 4, the laser-sensitive material 520 is placed inside the vacuum chamber 20 when the apparatus 10 is in a profiling configuration (while the intensity profile of the laser beam is being measured), and the sensor device 521 is placed outside the vacuum chamber 20. In such embodiments, the sensor device 521 is under ambient pressure while the intensity profile of the laser beam is being measured. Advantageously, this can avoid overheating of the sensor device 521.

[0111] The laser-sensitive material 520 may be placed on a holder 60 positioned on the sample stage 70 when the apparatus 10 is in a profiling configuration (i.e., while the intensity profile of the laser beam is being measured), as shown in Figure 5B. The holder 60 employed in such embodiments may be any known sample holder. Alternatively, the laser-sensitive material 520 may be placed directly on the sample stage 70 while the apparatus 10 is in a profiling configuration, as shown in Figure 5A. In such an arrangement, the sensor device 521 is optionally placed outside the vacuum chamber 20 and therefore does not need to conform to vacuum conditions, which may be UHV conditions. By placing the sensor device 521 outside the vacuum chamber but placing the laser-sensitive material 520 inside the vacuum chamber while the intensity profile is being measured, the intensity profile of the laser beam can be measured in situ without requiring an arrangement that conforms the sensor device 521 to vacuum conditions. Such embodiments would avoid overheating of the sensor device 521, as well as the resulting degradation and gas release from the sensor device 521. Furthermore, if the sensor device 521 is positioned outside the vacuum chamber 20, data can be transmitted from the sensor device 521 using a wired connection without requiring opening, and therefore without requiring subsequent ventilation of the vacuum chamber 20, or the use of a feedthrough connection. The sensor device 521 may be positioned outside the vacuum chamber 20 during intensity profile measurement to receive radiation from the laser-sensitive material 520 inside the vacuum chamber 20 through a window 26 inside the vacuum chamber 20. In such an arrangement, the window 26 would be configured to transmit radiation from the laser-sensitive material through it. For example, the window 26 may be made of glass.

[0112] Alternatively, the sensor device 521 may be placed inside the vacuum chamber 20 when the apparatus 10 is in a profiling configuration (i.e., during measurement of the intensity profile), as shown in Figure 7. When the apparatus 10 is in a profiling configuration, as shown in Figure 8B, the sensor device 521 may be supported on a holder 60' referred to herein as a sensor holder 60', which can be configured to reduce overheating of the sensor device 521 when operating under vacuum conditions. This is advantageous for reducing gas emission from the sensor device 521 or degradation of the sensor device 521. The sensor holder 60' will be discussed in more detail below. In the exemplary embodiment shown in Figure 7, the laser-sensitive material 520 is configured to produce radiation to irradiation by a laser beam and is coated directly onto the sensing surface 521a of the sensor device 521. "Directly" means that there is no intervening material between the laser-sensitive material 520 and the sensing surface 521a of the sensor device 521. When the apparatus 10 is in a profiling configuration (i.e., during measurement of the intensity profile of a laser beam), the sensor device 521 may be positioned and / or the laser beam may be directed so that the laser-sensitive material 520 intersects with the laser beam at a reference position 300.

[0113] In one embodiment, the laser-sensitive material 520 may be configured to undergo a visible change in response to irradiation by a laser beam, and the visible change may correlate with the intensity of the laser beam irradiating it. The visible change may be, for example, a color change of the photosensitive material 520, where there is a correlation between the color change of the photosensitive material 520 and the intensity of the laser beam irradiating it. The visible change may be, for example, a visible change in the texture of the photosensitive material 520, where there is a correlation between the texture change of the photosensitive material 520 and the intensity of the laser beam irradiating it.

[0114] For example, the laser-sensitive material 520 may be configured to be ablated by the laser beam irradiating it when the laser is operating in profiling mode. The laser-sensitive material 520 may be configured to undergo different color and / or texture changes as a result of the depth of ablation, which may correlate with the intensity of the laser beam irradiating the laser-sensitive material 520. For example, the laser-sensitive material 520 may be formed from multiple layers of different colors and / or textures. The depth of ablation of the laser-sensitive material 520 by the laser beam may change as a result of changes in the intensity of the laser beam on the laser-sensitive material 520. The changing depth of ablation may result in the exposure of different layers of the laser-sensitive material 520. If the layers of the laser-sensitive material 520 have different textures and / or colors, imaging of the laser-sensitive material 520 by the sensor device 521 after irradiation with the laser beam may be used to determine the changing depth of ablation across the laser-sensitive material 520. Next, the varying intensity of the laser beam at the reference position 300 can be determined from the varying depth of ablation across the laser-sensitive material 520. A sensor device 521 and / or a processing device 120 that may be connected to the sensor device 521 may be configured to generate an intensity profile of the laser beam at the reference position 300 based on the imaging of the laser-sensitive material 520 after irradiation with the laser beam. The generated intensity profile is a 2D (in the profiling plane) intensity profile of the laser beam at the reference position 300.

[0115] In embodiments employing a laser-sensitive material 520 configured to undergo visible changes in response to irradiation by a laser beam, the sensor device 521 may be a camera configured to image the laser-sensitive material 520. The sensor device 521 may be located inside or outside the vacuum chamber when the apparatus 10 is in a profiling configuration (i.e., during measurement of the intensity profile of the laser beam). The sensor device 521 may be positioned to image the laser-sensitive material 520 during the measurement of the intensity profile. In particularly advantageous embodiments, such as the embodiment shown in Figure 4, when the apparatus 10 is in a profiling configuration, the laser-sensitive material 520 is located inside the vacuum chamber 20, and the sensor device 521 is located outside the vacuum chamber. In such embodiments, the sensor device 521 is under ambient pressure during the measurement of the intensity profile. The sensor device 521 may be located outside the vacuum chamber in a position that allows the sensor device 521 to image the laser-sensitive material 520 inside the vacuum chamber 20 through a window 26 inside the vacuum chamber 20. In such an arrangement, the window 26 may be transparent. For example, the window 26 may be made of glass. In such an arrangement, the sensor device 521 does not need to be adapted to vacuum conditions that may be UHV conditions. When the apparatus 10 is in a profiling configuration, the sensor device 521 is placed outside the vacuum chamber, but by placing the laser-sensitive material 520 inside the vacuum chamber 20, the intensity profile of the laser beam can be measured in situ without requiring the sensor device 521 to be adapted to vacuum conditions. Such an arrangement would avoid overheating and degradation of the sensor device 521. Such an arrangement would avoid contamination of the vacuum chamber 20 due to gas release from the sensor device 521.

[0116] Optionally, the beam profiler 500 includes a reflector 522 configured to image the laser-sensitive material 520 or reflect photons from the laser-sensitive material 520 toward a sensor device 521, which is optionally a camera. An exemplary embodiment of such an arrangement is shown in Figure 4. Such an arrangement may be employed, for example, when the laser-sensitive material 521 is configured to emit visible light or to undergo a visible change in response to irradiation by a laser beam.

[0117] In certain advantageous embodiments, the laser-sensitive material 520 may be sensitive to both the imaging beam and the laser beam. As a result, the laser-sensitive material 520 may be used for the alignment of the laser beam and the imaging beam, as will be discussed in more detail in the context of this method. The alignment of the laser beam and the imaging beam may be such that the imaging beam coincides with the laser beam at reference position 300. The alignment of the laser beam and the imaging beam may be such that the imaging position coincides with the reference position. Coincidence as used herein refers to a spatial coincidence where there is at least some overlap between them. Coincidence between the imaging beam and the laser beam does not require that the laser beam has the same spatial range as the imaging beam at the coincidence point. The alignment of the laser beam and the imaging beam may be such that the irradiation area of ​​the laser-sensitive material 520 by the imaging beam at least partially, preferably completely, overlaps with the irradiation area of ​​the laser-sensitive material 520 by the laser beam. As discussed above, the shape of the laser beam may be configured to achieve a substantially top-hat or flat-top intensity profile at reference position 300. Preferably, the alignment of the laser beam and the imaging beam may be such that the irradiation area of ​​the laser-sensitive material 520 by the imaging beam overlaps with only a portion of the laser beam having a flat-top or top-hat intensity profile.

[0118] The laser-sensitive material 520 may be configured to undergo detectable changes and / or generate radiation in response to irradiation with a laser beam and / or an imaging beam. Detectable changes and / or radiation emitted as a result of irradiation of the laser-sensitive material with an imaging beam may be distinguishable from detectable changes and / or radiation emitted as a result of irradiation of the laser-sensitive material with a laser beam. For example, if the laser-sensitive material is an emissive material, the photons emitted in response to irradiation with a laser beam may have different wavelengths than the photons emitted in response to irradiation with an imaging beam.

[0119] As discussed above, the sensor device 521 may be employed to detect changes in the laser-sensitive material 520 and / or radiation from the laser-sensitive material 520 caused by irradiation with a laser beam. The same sensor device 521 or additional sensor devices (not shown) may be used to detect changes in the laser-sensitive material 520 and / or radiation from the laser-sensitive material 520 caused by irradiation with an imaging beam. If additional sensor devices are employed, they may be positioned remotely from the laser-sensitive material 520. The sensor device 521, and any additional sensor devices employed, and / or the processing device 120 may be configured to determine the irradiation area of ​​the laser-sensitive material 520 by the imaging beam and the irradiation area of ​​the laser-sensitive material 520 by the laser beam. The processing device 120 may be configured to determine whether the irradiation area of ​​the laser-sensitive material 520 by the laser beam overlaps, at least partially, and optionally, completely with the irradiation area of ​​the laser-sensitive material 520 by the imaging beam. The processing device 120 may be configured to determine adjustments to the laser beam assembly 40 and / or the imaging beam assembly 50 such that the irradiation area by the imaging beam at least partially overlaps with the irradiation area by the laser beam. The determined adjustments may, for example, be adjustments to the positioning of the optical components of the laser beam assembly 40 and / or the imaging beam assembly 50.

[0120] In one embodiment, the laser-sensitive material 520 may include a light-emitting material, such as a phosphorescent material and / or a fluorescent material, configured to emit photons in response to irradiation by a laser beam and by irradiation by an imaging beam. The laser-sensitive material 520 may include a single light-emitting material configured to emit photons in response to irradiation by a laser beam and in response to irradiation by an imaging beam. For example, the laser-sensitive material 520 may include a phosphor configured to convert both photons from the laser beam and photons from the imaging beam into visible light. For example, the imaging beam may be an X-ray beam, the laser beam may be a UV laser beam, and the laser-sensitive material 520 may be a phosphor configured to convert UV photons and X-ray photons into visible light.

[0121] The laser-sensitive material 520 may include a mixture of light-emitting materials, the mixture of light-emitting materials including a first light-emitting material configured to emit photons in response to irradiation with a laser beam, and a second light-emitting material configured to convert photons in response to irradiation with an imaging beam, the first and second light-emitting materials. Each light-emitting material may be a phosphorescent or fluorescent material. The laser-sensitive material 520 may also include a mixture of phosphors, the mixture of phosphors including a first phosphor configured to convert photons from a laser beam into visible light, and a second phosphor configured to convert photons from an imaging beam into visible light. For example, the imaging beam may be an X-ray beam, the laser beam may be a UV laser beam, and the laser-sensitive material 520 may include a first phosphor configured to convert UV photons into visible light, and a second phosphor configured to convert X-ray photons into visible light.

[0122] In one embodiment, the laser-sensitive material 520 may be configured to undergo visible changes, such as color changes and / or texture changes, in response to irradiation by an imaging beam and by a laser beam. As discussed above, the sensor device 521 may be employed to image the visible changes of the laser-sensitive material 520 resulting from irradiation by a laser beam. The same sensor device 521 or a further sensor device (not shown) may be configured to image the visible changes of the laser-sensitive material 520 resulting from irradiation of the laser-sensitive material 520 by an imaging beam. In such embodiments, the sensor device 521 may be a camera. The processing device 120 connected to the sensor device 521 may then determine, based on the image of the laser-sensitive material received from the sensor device 521 (and any further sensor devices employed), whether the imaging beam is aligned with the laser-sensitive material. The processing device 120 can make adjustments to the laser beam assembly 40 and the imaging beam assembly 50, for example, by determining the positioning of the optical components of the laser beam assembly 40 and / or the imaging beam assembly 50 to achieve mutual alignment of the imaging beam and the laser beam based on imaging.

[0123] As discussed above, the laser-sensitive material 520 may be configured to generate and / or undergo radiation, the radiation or change correlates with the intensity of the laser beam irradiating it, and therefore the intensity profile of the laser beam can be generated based on the detected radiation / change and correlation. It is not necessary to generate an intensity profile of the imaging beam in order to align the imaging beam with the laser beam. Therefore, the laser-sensitive material 520 may be configured to generate and / or undergo radiation, and the radiation or change does not need to correlate with the intensity of the imaging beam. In fact, instead, the alignment of the imaging beam and the laser beam may be carried out based on detecting whether the irradiation area of ​​the laser-sensitive material 520 by the laser beam overlaps at least partially, preferably completely, with the irradiation area of ​​the laser-sensitive material 520 by the imaging beam. Nevertheless, in some embodiments, the laser-sensitive material 520 may be configured to generate and / or undergo radiation in response to irradiation by the imaging beam, and those radiations and / or changes correlate with the intensity of the imaging beam. In such embodiments, the intensity profile of the image can be generated by the sensor device 521 and / or the processing device 120 coupled to the sensor device 521. Such an intensity profile is 2D (in the profile plane).

[0124] As discussed above, instead of the laser-sensitive material 520, the beam profiler may include a laser sensor 530 configured to measure the intensity profile of a laser beam, as shown in Figure 6. The laser sensor 530 may intersect with the laser beam at reference position 300 when the apparatus 10 is in profiling configuration (i.e., while the intensity of the laser beam is being measured). In particular, the sensing surface 530a of the laser sensor 530 may intersect with the laser beam at reference position 300 when the apparatus 10 is in profiling configuration. The laser beam may be directed such that the reference position 300 is located inside the vacuum chamber 20, as discussed above. As shown in Figure 6, the laser sensor 530 may therefore be located inside the vacuum chamber 20 when the apparatus 10 is in profiling configuration (i.e., while the intensity profile of the laser beam is being measured). Thus, the laser sensor 530 can be used to measure the intensity profile of a laser beam in the field. The vacuum chamber may be an ultra-high vacuum chamber, and the laser sensor 530 may be suitable for ultra-high vacuum (UHV) conditions. Suitable means that the laser sensor 530 does not significantly degrade or release gas when it is inside the vacuum chamber 20 under UHV conditions. The laser sensor 530 may include or consist of one or more cameras, such as a CCD camera or a CMOS camera. The camera may have a coating thereon that acts as a neutral density filter to reduce damage to the camera by the laser beam. The camera may be configured to detect the intensity of the laser beam received on its sensing surface 530a and to produce an image of the intensity distribution of the laser beam. The use of such cameras to measure the intensity profile of a laser beam and to produce an image of the intensity distribution of the laser beam is known in the art, but such cameras are susceptible to degradation and overheating when placed under vacuum conditions. According to the apparatus of the present invention, the laser sensor 530 may be supported on a holder 60' referred to herein as a sensor holder 60', which can be configured to reduce overheating of the laser sensor 530 when operating under vacuum conditions, as shown in Figure 8A. This is advantageous in reducing gas emission from the laser sensor 530 or degradation of the laser sensor 530.The sensor holder 60' will be discussed in more detail below.

[0125] The laser sensor 530 may be configured to sense both the laser beam and the imaging beam, and therefore can be used for the alignment of the laser beam and the imaging beam. The laser sensor 530 may be configured to distinguish between irradiation received as a result of the laser beam and irradiation received as a result of the imaging beam. As discussed above, the laser sensor 530 may be configured to detect the intensity of its irradiation by the laser beam on it. The laser sensor 530 may be configured to detect at least the irradiation area, and optionally the irradiation intensity by the imaging beam. A processing device 120 connected to the laser sensor may determine whether the imaging beam is aligned with the laser-sensitive material based on a comparison of the irradiation area by the imaging beam detected by the laser sensor 530 with the irradiation area by the laser beam detected by the laser sensor 530. The processing device 120 may adjust the laser beam assembly 40 and the imaging beam assembly 50, for example, determine the positioning of the optical components of the laser beam assembly 40 and / or imaging beam assembly 50 to achieve the alignment of the imaging beam and the laser beam based on the detected area. For example, the imaging beam could be an X-ray beam, and the laser beam could be a UV laser beam. The laser sensor 530 could be a sensor, such as a camera, for example, a CCD camera, that can detect both X-rays and UV rays.

[0126] The imaging beam assembly 50 and the laser beam assembly 40 can be controlled so that the beam width of the imaging beam at the imaging position is the same as, preferably smaller than, the beam width of the laser beam at the reference position 300.

[0127] The apparatus 10 may further include a load lock 30 coupled to the vacuum chamber 20. The sample 110 and / or profiling element 510 can be inserted into and removed from the vacuum chamber 20 via the load lock 30.

[0128] As discussed above, the profiling element 510 may be (i) a laser-sensitive material 520 (as in the embodiment shown in Figure 4), (ii) a laser-sensitive material 520 coated on a sensor device 521 (as in the embodiment shown in Figure 6), or (iii) a laser sensor 530 (as in the embodiment shown in Figure 7).

[0129] As discussed above, the sample stage 70 may be configured to support a sample 110 (not shown in Figure 1) and / or a profiling element 510 on it. Referring to the x, y, and z directions shown in Figure 1, the sample stage 70 may be translationally movable in the xy-plane and may be tiltable relative to the xy-plane. The sample stage 70 may also be movable in the z-direction. If the sample stage 70 is not tilted relative to the xy-plane and receives the sample 110 and / or profiling element 510 on it, the sampling plane and / or profiling plane may be positioned parallel to the xy-plane. Alternatively, the sample stage 70 may be tilted at a non-zero angle relative to the xy-plane so that the sample plane and / or profiling plane can be positioned at a non-zero angle relative to the xy-plane and receive the sample 110 and / or profiling element 510 on it. In arrangements where the area of ​​the profiling element in the profiling plane is smaller than the beam width of the laser beam at the reference position, and the profiling element can be translated across the area of ​​the laser beam spot at the reference position, such translation can be achieved by the translation of the sample stage 70 on which the profiling element 510 is located.

[0130] The sample stage 70 may be configured to receive the sample 110 and the profiling element 510 at separated locations on the sample stage 70, as shown in Figure 5A. The locations are separated along the surface of the sample stage 70. The locations may be separated in the xy plane. As shown in Figure 5A, the location where the sample 110 is received may also be separated from the location where the profiling element 510 is received in the z direction. In fact, in the exemplary embodiment shown in Figure 5A, the profiling element is optionally received on a raised portion 70a of the sample stage 70 that is separated from the location of the sample 110 in the xy plane.

[0131] Alternatively, the sample stage 70 may be configured to accept the sample 110 and the profiling element 510 separately. For example, the sample stage 70 may be configured to accept either the sample 110 or the profiling element at the same location on the sample stage 70.

[0132] The sample stage 70 may include a heat sink 71 configured to receive heat generated by the profiling element 510 when the profiling element 510 is supported on the sample stage 70. The heat sink 71 may be a thermally conductive mass within the sample stage 70, such as a metal block formed from aluminum, stainless steel, etc. The sample stage 70 may be formed at least partially from a thermally conductive material that forms the heat sink 71. The heat sink 71 may be thermally coupled to the profiling element 510 when the profiling element 510 is placed on the sample stage 70. The thermal coupling between the sample stage 70 and the profiling element 510 may be maintained during the movement of the sample stage 70.

[0133] The sample 110 and / or profiling element 510 may be placed directly on the sample stage 70. Alternatively, the sample 110 and / or profiling element 510 may be supported by a holder 60, as shown in Figure 1, and then placed on the sample stage 70. The holder 60 may be configured to support either the sample 110 or the profiling element 510. Different holders 60 may be used for each of the sample 110 and the profiling element 510. Alternatively, the holder 60 may be configured to support both the sample 110 and the profiling element 510 simultaneously.

[0134] A transfer component, for example, a transfer rod (not shown), is configured to be mechanically releasably coupled to the holder 60 and may be configured to move the holder 60 in and out of the vacuum chamber 20, for example, via an optional load lock 30. When the holder 60 is positioned in a predetermined location within the vacuum chamber 20, the transfer component can be mechanically discoupled from the holder 60. The transfer component may be, for example, a transfer rod that is threaded and can be removably attached to the holder 60 by screwing it into a corresponding recess in the holder 60.

[0135] The apparatus 10 may include a stage positioning mechanism (not shown) configured to adjust the position of the sample stage 70. The stage positioning mechanism may be configured to adjust the position of the sample stage 70 in the xy plane and / or the z direction. The stage positioning mechanism may be configured to adjust the position of the sample stage 70 by rotational motion in a plane, such as rotation in the xy plane. For example, the stage positioning mechanism may be configured to rotate the sample stage 70 about an axis in the z direction. The apparatus 10 may also include a tilting mechanism for tilting the sample stage 70 at a non-zero angle with respect to the xy plane. The positioning and / or tilting mechanism used to position the sample stage 70 may be controlled by a controller 100.

[0136] In an arrangement where the profiling element 510 and the sample 110 are simultaneously placed on the sample stage 70, the controller 100 may be configured to control the sample stage positioning mechanism to translate or rotate the sample stage 70, thereby reconfiguring the device between a profiling configuration in which the profiling element 510 intersects the laser beam at a reference position 300 and an analytical configuration in which the sample 110 intersects the laser beam at a reference position 300.

[0137] Alternatively, the sample stage 70 may be configured to receive the sample 110 and the profiling element 510 separately. For example, the sample stage may first receive a holder 60 supporting the profiling element 510 on top, and then the holder 60 may optionally be removed from the vacuum chamber 20 via a load lock 30. The profiling element 510 may be replaced with the sample 110 before the holder 60 is reinserted into the vacuum chamber under the load lock 30. Alternatively, the holder 60 having the profiling element 510 on top may be replaced with a different holder 60 having the sample 110 on top.

[0138] If the profiling element 510 is a laser-sensitive material 520, the holder 60 employed to support the laser-sensitive material 520 may be a standard sample holder known in the art, as shown in Figure 5A. In such embodiments, the sensor device 521 may be positioned remotely from the laser-sensitive material 520, as shown in Figure 5A, and the laser-sensitive material 520 may be positioned directly on the surface of the holder 60. The upper surface of the holder 60 may be configured to receive the laser-sensitive material 520, and the lower surface of the holder 60 may be configured to engage with the sample stage 70. The terms upper and lower refer to the orientation of the holder 60 in normal use during measurement of the intensity profile of a laser beam.

[0139] If the profiling element 510 is a laser-sensitive material 520 coated on a sensor device 521, or if the profiling element 510 is a laser sensor 530, employing a standard sample holder known in the art to support the laser sensor 530 or sensor device 521 may result in overheating and degradation of the sensor device 521 or laser sensor 530. However, the inventors have created a holder 60' referred to herein as sensor holder 60', which can be used to mechanically and / or thermally and / or electrically couple the sensor device 521 or laser sensor 530 to the sample stage 70 in a releasable manner, and to mitigate overheating and damage to the sensor device 521 or laser sensor 530 when used under vacuum conditions. The sensor holder 60' is shown in Figures 8A, 8B, and 8C. The thermal and / or electrical and / or mechanical coupling between the profiling element 510 and the sample stage 70 via the sensor holder 60' can be maintained during movement of the sample stage 70.

[0140] The sensor holder 60' may be configured to hold and / or support the sensor device 521 or the laser sensor 530. The sensor holder 60' may be configured to be mechanically coupled to the sample stage 70. Preferably, the sensor holder 60' may be configured to be mechanically coupled to the sample stage 70 in a releasable manner. The upper surface of the sensor holder 60' may be configured to receive the sensor device 521 (on which the laser-sensitive material 520 is coated) or the laser sensor 530 thereon, and the lower surface of the sensor holder 60' may be configured to engage with the sample stage 70. The terms upper and lower refer to the orientation of the sensor holder 60' in normal use during measurement of the intensity profile of a laser beam. The sensor holder 60' and the sample stage 70 may include releasable complementary engagement means, such as corresponding pins and recesses / grooves. The releasable complementary engagement means may be configured to generate an electrical signal for engagement, which may be received by, for example, the processor 120 or the controller 100. Such electrical signals may be useful for confirming the mechanical engagement between the sensor holder 60' and the sample stage 70. In the exemplary embodiment shown in Figure 8C, the releasable complementary engagement optionally comprises a pin 61 protruding from the lower surface of the sensor holder 60' and optionally a corresponding recess 72 formed on the upper surface of the sample stage 70.

[0141] The sensor holder 60' may be configured to thermally couple the sample stage 70 to the sensor device 521 or the laser sensor 530 located on the sensor holder 60' when the sensor holder 60' is mechanically coupled to the sample stage 70. If the sample stage 70 includes a heat sink 71 as discussed above, the sensor holder 60' may be configured to thermally couple the heat sink 71 of the sample stage 70 to the laser sensor 530 or the sensor device 521 located on the sensor holder 60' when the sensor holder 60' is mechanically coupled to the sample stage 70. For example, the sensor holder 60' may include one or more holder thermal coupling elements 62 that thermally couple to the sensor device 521 or the laser sensor 530 when the sensor device 521 or the laser sensor 530 is located on the sensor holder 60'. The holder thermal coupling elements 62 may be configured to releasably thermally couple to the heat sink 71 of the sample stage 70 when the sensor holder 60' is mechanically coupled to the sample stage 70. Therefore, when the holder 60' is mechanically discoupled from the sample stage 70, the holder thermal coupling element 62 and the heat sink 71 are also thermally discoupled. The holder thermal coupling element 62 may be made of a thermally conductive material and may extend between the upper surface and the lower surface of the sensor holder 60'. The holder thermal coupling element 62 may be configured to directly contact the laser sensor 530 or sensor device 521 when the laser sensor 530 or sensor device 521 is positioned on the sensor holder 60'.

[0142] In the exemplary embodiment shown in Figure 8C, the thermal coupling element 62 is optionally a thermally conductive via extending through the thickness of the sensor holder 60' between the top and bottom surfaces of the sensor holder 60'. The conductive via is a through-hole filled with a thermally conductive material and extending through the thickness of the sensor holder 60' (from the top surface to the bottom surface of the sensor holder 60'). In the exemplary embodiment shown in Figure 8C, the heat sink 71 forms part of the top surface of the sample stage 70. Thus, when the sample stage 70 and the sensor holder 60' are mechanically coupled together, the heat sink 71 can be aligned with and in direct contact with the thermal coupling element 62.

[0143] In alternative embodiments not shown, the heat sink 71 may not form part of the upper surface of the sample stage 70. In such an arrangement, the sample stage 70 may include stage thermal coupling elements, such as one or more thermally conductive vias, extending between the heat sink 71 and the upper surface of the sample stage 70.

[0144] The sample stage 70 may be configured to electrically couple to the sensor device 521 or laser sensor 530 when the sensor device 521 or laser sensor 530 is placed on it (indirectly or directly), and to optionally transfer power to and / or data from the sensor device 521 or laser sensor 530. The sample stage 70 may be configured to electrically couple to the sensor device 521 or laser sensor 530 via the sensor holder 60' when the sensor holder 60' and the sample stage 70 are mechanically coupled together. The sample stage 70 and the holder 60' may be electrically coupled together in a way that allows them to be released together, so that when the sensor holder 60' and the sample stage 70 are mechanically discoupled, the sample stage 70 is also electrically discoupled from the sensor holder 60'. Thus, the sensor device or laser sensor will be powered and / or operate for data transmission only when mechanically coupled to the stage via the sensor holder 60', and therefore when positioned to measure the intensity profile of a laser beam. Limiting the time that the laser sensor or sensor device is powered and / or operates for data transfer is advantageous in reducing overheating of the laser sensor or sensor device within the vacuum chamber 20.

[0145] In embodiments where the sample stage 70 is configured to transfer power to the sensor device 521 or laser sensor 530 when the sensor device 521 or laser sensor 530 is received on top of it, the sample stage 70 may be electrically connected to a power supply 800 which may be located outside the vacuum chamber 20. The sample stage 70 may be electrically coupled to the power supply 800 via a fixed (i.e., permanent) electrical connection, for example, via a wired connection, as shown in Figures 6, 7, and 8C. The sample stage 70 may be configured to be electrically releasably coupled to the laser sensor or sensor device via a sensor holder 60' when the laser sensor or sensor device is received on top of it.

[0146] In embodiments where the sample stage 70 is configured to transfer data from the sensor device 521 or laser sensor 530 when the sensor device 521 or laser sensor 530 is received on top of it, the sample stage 70 may be electrically coupled to a processing device 120 which may be located outside the vacuum chamber 20. The sample stage 70 may be electrically coupled to the processing device 120 via a fixed (i.e., permanent) electrical connection, such as a wired connection, as shown in Figures 6, 7, and 8C. A wired connection is particularly advantageous for achieving high-speed, low-noise data transfer. The sample stage 70 may be configured to be electrically and releasably coupled to the laser sensor 530 or sensor device 521 via a sensor holder 60' when the laser sensor 530 or sensor device 521 is received on top of it.

[0147] Therefore, the sensor holder 60' allows data to be transferred from the sensor device 521 or laser sensor 530 located inside the vacuum chamber 20 using a wired connection, and / or power to be transferred to the sensor device 521 or laser sensor 530, without the need to open the vacuum chamber 20 and make connections. Thus, the sensor device 521 or laser sensor 530 can measure the intensity profile of a laser beam in the field under vacuum conditions without risking contamination of the vacuum chamber 20 or requiring the vacuum chamber 20 to be ventilated after the intensity profile has been measured.

[0148] The sample stage 70 may include an electrical coupling element 700, referred herein as the stage electrical coupling element 700. The sensor holder 60' may include an electrical coupling element 600, referred herein as the holder electrical coupling element 600. The holder electrical coupling element 600 may be electrically coupled to the sensor device 521 or the laser sensor 530 via a fixed (i.e., permanent) electrical connection, such as a wired connection.

[0149] The holder electrical coupling element 600 may be configured to be electrically releasably coupled to the stage electrical coupling element 700 when the sensor holder 60' is mechanically coupled to the sample stage 70. In particular, the holder electrical coupling element 600 and the stage electrical coupling element 700 may be configured to be electrically releasably coupled together such that when the holder 60' is mechanically discoupled from the sample stage, the holder electrical coupling element 600 is electrically discoupled from the stage electrical coupling element 700. The holder electrical coupling element 600 and the stage electrical coupling element 700 may be configured to transfer power to and / or data from the sensor device 521 or laser sensor 530 located on the sensor holder 60' when the holder electrical coupling element 600 and the stage electrical coupling element 700 are electrically coupled together.

[0150] If the sample stage 70 comprises a heat sink 71 and a stage electrical coupling element 700, as shown in Figure 8C, the stage electrical coupling element 700 may be electrically insulated from the heat sink 71. For example, the sample stage 70 may include an electrically insulating (and optionally thermally insulating) material that separates the electrical coupling element 700 from the heat sink 71. The sample stage 70 may be formed of an electrically insulating (and optionally thermally insulating) material, except for the heat sink 71, the stage electrical coupling element 700, and the stage thermal coupling element (if present).

[0151] If the sensor holder 60' includes a holder thermal coupling element 62 and a holder electrical coupling element 600, as shown in Figures 8A, 8B, and 8C, the holder electrical coupling element 600 may be electrically insulated from the holder thermal coupling element 62. For example, the sensor holder 60' may include an electrically insulating (and optionally thermally insulating) material that separates the holder electrical coupling element 600 from the holder thermal coupling element 62. The sensor holder 60' may be formed of an electrically insulating (and optionally thermally insulating) material, except for the holder electrical coupling element 700 and the holder thermal coupling element 62.

[0152] As shown in Figure 8C, the stage electrical coupling element 700 may include one or more stage electrical contacts 710. As shown in Figures 8A to 8C, the holder electrical coupling element 600 may include one or more holder electrical contacts 610. The holder electrical contacts 610 may be configured to align with and directly contact the stage electrical contacts 710 when the sensor holder 60' and the sample stage 70 are mechanically coupled together. The holder electrical contacts 610 may be located on the underside of the sensor holder 60'. The stage electrical contacts 710 may be located on the upper side of the sample stage 70. The stage electrical contacts 710 and the holder electrical contacts 610 may be formed from a conductive material.

[0153] As shown in Figures 8A to 8C, the holder electrical coupling element 600 may include an electrical connector, referred to herein as the holder electrical connector 620, which provides an electrical connection between the holder electrical contacts 620 and the sensor device 521 or laser sensor 530 on the sensor holder 60'. The holder electrical connector 620 may be configured to transmit power and / or data between the holder electrical contacts 610 and the laser sensor 530 or sensor device 521 on the sensor holder 60'. The holder electrical connector 620 may be permanently electrically connected to the holder electrical contacts 610. For example, the holder electrical connector 620 may be soldered to the holder electrical contacts 610. The holder electrical connector may be configured to be releasably electrically connected to the sensor device 521 or laser sensor 530 when the sensor device 521 or laser sensor 530 is received on the sensor holder 60'. For example, the holder electrical connector 620 may be configured to be releasably electrically connected to a port, such as a USB port, on the sensor device 521 or laser sensor 530. Such an arrangement allows the sensor device 521 or laser sensor 530 to be removed from the holder 60' and optionally replaced. The holder electrical connector 620 may include a wired connection comprising one or more wires and / or conductive vias extending from the holder electrical contacts to the upper surface of the sensor holder 60' for connection to the laser sensor 530 or sensor device 521 thereon. Optionally, the wired connection may include one or more pairs of twisted wires.

[0154] In the exemplary embodiments shown in Figures 8A to 8C, the holder electrical coupling element 600 includes a holder electrical contact 610 located on the lower surface of the holder 60', and the holder electrical connection 620 is a wired connection configured to be permanently electrically connected to the holder electrical contact and to be electrically releasably connected to the laser sensor 530 or sensor device 521 when located on the upper surface of the holder 60'. The wires of the wired connection optionally extend between the lower and upper surfaces of the sensor holder 60' through through holes formed in the thickness of the sensor holder 60'. Alternatively, however, the wires of the wired connection may extend around the outside of the sensor holder 60' between the lower and upper surfaces of the sensor holder 60'. The wired connection optionally comprises one or more pairs of twisted wires.

[0155] As shown in Figure 8C, the stage electrical coupling element 700 may further include an electrical connector, referred to herein as the stage electrical connector 720, between the stage electrical contacts 710 and the power supply 800. The power supply 800 and / or processing device 120 may be located outside the vacuum chamber 20. The stage electrical connector 720 may include a wired connection between the stage electrical contacts 710 and the power supply 800 and / or processing device 120, as shown in Figure 8C. The wired connection may extend through a vacuum feedthrough 900 between the inside and outside of the vacuum chamber. The wired connection may include a first wired connection between the stage electrical contacts 710 and the vacuum feedthrough, and a second wired connection between the vacuum feedthrough 900 and the power supply 800 and / or processing device 120. The first and / or second wired connection may include one or more pairs of twisted wires.

[0156] In particularly advantageous embodiments, the holder electrical connector 620 includes one or more pairs of twisted wires, and the first wire connection of the stage electrical connector 720 includes one or more pairs of twisted wires. Employing pairs of twisted wires for data and power transfer within the vacuum chamber 20 is advantageous for maintaining signal integrity and reducing noise interference.

[0157] In a particularly advantageous embodiment, a releasable electrical coupling between the sample stage 70 and the sensor device 521 or laser sensor 530 via the sensor holder 60' may be configured to transfer both power to the sensor device 521 or laser sensor 530 and data from the sensor device 521 or laser sensor 530 when the sensor holder 60' and the sample stage 70 are mechanically coupled together. However, embodiments in which data transfer from the sensor device and / or laser sensor is carried out by a separate data connection are also contemplated. The data connection may be a wireless data connection, such as Bluetooth. The data connection may be between the sensor device 521 or laser sensor 530 and the processing device 120.

[0158] In some embodiments, the sensor holder 60' may optionally be formed integrally with the sensor device 521 or the laser sensor 530.

[0159] Exemplary Embodiments of the Method Exemplary embodiments of the method according to the present invention are shown in Figures 9 to 11. A controller 100 may be employed to control and bring about the execution of the described method. The controller 100 may comprise logic (e.g., in the form of software instructions) for controlling and bringing about the execution of the steps of the method described herein. The controller may comprise non-temporary memory for storing computer-readable instructions and a processor for executing computer-readable instructions. The method disclosed herein may be implemented by executing computer-readable instructions within the processor. The processor of the controller may be the processing device 120 discussed above. The method may optionally be implemented using the apparatus 10 discussed above, as schematically illustrated in Figures 12 and 13. The controller 100 may be employed to control the features of the apparatus 10 for implementing the method. For example, the controller 100 may control a stage positioning mechanism and / or a stage tilting mechanism that may be used to position the sample stage 70; the controller 100 may control the movement of a transport element if it is employed to move the sample 110 and / or profiling element 510; the controller 100 may control the movement of optical elements of a laser beam assembly 40, such as a beam shaper, to adjust the shape of the laser beam at a reference position 300 based on a measured intensity profile; and the controller may control the features of an imaging beam assembly 50 used to generate and direct an imaging beam.

[0160] The order of the method steps shown in Figures 9-11 and illustrated in Figures 12 and 13 may be modified if the context allows, and some of the method steps may be performed simultaneously. Furthermore, if it is stated that one step is performed after another, this does not preclude the performance of an intervening step.

[0161] Step 101 The method shown in Figure 9 is a method for operating a spectroscopic or microscopic apparatus according to the invention of the claims. The spectroscopic or microscopic apparatus may be the apparatus 10 discussed above.

[0162] According to the method in Figure 9, the laser beam is directed along a trajectory through the apparatus, and the intensity profile of the laser beam is measured at a reference position 300 in the trajectory (step 101). This step may be referred to herein as the profiling step. The resulting intensity profile may be the intensity of the laser beam in 2D within the profiling plane at the reference position 300. The intensity profile may be represented as a heatmap. The heatmap may be a 2D map employing a color scale to show the intensity of the laser beam in the profiling plane. Alternatively, for example, the intensity profile may be represented on a 3D plot. The x, y coordinates of the plot representing the shape laser profile in the profiling plane, and the z coordinate representing the intensity of the laser beam in the profiling plane. As a further alternative, the intensity profile may be provided on a graph showing the intensity through a line cross section of an area plot.

[0163] When used to perform the method shown in Figure 9, the apparatus 10 may be placed in a profiling configuration during step 101.

[0164] As discussed above, the reference position 300 may be at a fixed distance from the focal point 320 of the laser beam, which is referred to herein as the reference distance RD. This is illustrated in Figure 2. As discussed above, the reference distance may be zero. Preferably, the reference distance is a non-zero distance such that the reference position 300 is separated from the focal point 320 of the laser beam. The reference position 300 may be upstream of the focal point of the laser beam. The reference distance may be, for example, 0.01 to 100 mm from the focal point of the laser beam, preferably 0.1 to 10 mm, and more preferably 1 to 5 mm from the focal point of the laser beam. The focal point of the laser beam may be defined as the focal distance from the objective lens that is focused when the laser beam is directed along its trajectory through the apparatus. The reference distance may be, for example, in the range of 0.01% to 5% of the focal length, preferably 0.1% to 5%, and more preferably 0.5% to 2.5% of the focal length. The reference distance may be predetermined. The reference distance may be selected by the user.

[0165] Optionally, the intensity profile of the laser beam at reference position 300 can be measured by irradiating a profiling element, such as the profiling element 510 discussed above, which intersects with the laser beam at reference position 300 during step 101. In other words, the profiling element 510 may intersect with the laser beam at reference position 300. In particular, the surface of the profiling element 510 may intersect with the laser beam at reference position 300. The plane of the surface of the profiling element 510 (profiling plane) intersects with the laser beam at a non-zero angle during the profiling step. The non-zero angle may be substantially the same as the expected non-zero angle between the sampling plane and the laser beam during sample ablation. During the step of measuring the intensity profile of the laser beam, at least a portion of the surface of the profiling element 510 in the profiling plane may be overlapped by the laser beam. The area of ​​the profiling element 510 in the profiling plane may be larger than the area of ​​the laser beam spot size at reference position 300. Alternatively, the area of ​​the profiling element 510 in the profiling plane may be smaller than the beam width of the laser beam at the reference position 300, and the profiling element may be translated across the area of ​​the laser beam spot at the reference position 300 during the profiling step so that the profiling element is scanned across the laser beam spot at the reference position 300 during the profiling step. The profiling element 510 may be part of a beam profiler such as the beam profiler 500 discussed above.

[0166] Step 101 may include directing the laser beam and / or positioning the profiling element 510 such that the profiling element 510 intersects the laser beam at the reference position 300. As discussed above, the laser beam may be directed such that the reference position 300 is located in the vacuum chamber of the apparatus, such as the vacuum chamber 20 discussed above, during step 101. Thus, the profiling element 510 may be located in the vacuum chamber 20 at least while the intensity profile of the laser beam is being measured, i.e., at least during step 201.

[0167] Before the intensity profile is measured, the method may include transporting the profiling element 510 to a location within the apparatus, optionally to a location within the vacuum chamber 20 of the apparatus 10. The profiling element 510 may be introduced into the vacuum chamber 20 via a load lock 30 to avoid disrupting the vacuum in the vacuum chamber 20.

[0168] Prior to the measurement of the intensity profile, the method may include placing the profiling element 510 on a sample stage in the apparatus, such as the sample stage 70 discussed above. Prior to the step of measuring the intensity profile, the method may include placing the profiling element 510 on the sample stage 70 in the vacuum chamber 20. The profiling element 510 may be placed directly (i.e., without intervening features) or indirectly (i.e., with intervening features) on the sample stage 70 in the vacuum chamber 20.

[0169] Placing the profiling elements 510 on the sample stage 70 may include adjusting the position of the sample stage 70 in the x, y plane and / or z direction, and / or tilting the sample stage 70. The positioning and / or tilting mechanisms discussed above may be used to adjust the position and / or tilt of the sample stage 70.

[0170] The profiling element 510 can be tilted, for example, by tilting the sample stage 70 when the profiling element 510 is placed on the sample stage 70, so that the angle between the laser beam and the profiling plane during the profiling step is the same as the expected angle between the laser beam and the sampling plane during the profiling step.

[0171] Placing the profiling element 510 on the sample stage 70 may involve mechanically and / or thermally and / or electrically coupling the profiling element 510 to the sample stage 70. As discussed above, mechanical coupling of the profiling element 510 to the sample stage 70 may result in thermal and / or electrical coupling of the profiling element 510 to the sample stage 70. As discussed above, the sample stage 70 may include a heat sink 71. Thermal coupling of the profiling element 510 to the sample stage 70 may result in heat transfer from the profiling element 510 to the heat sink 71 of the sample stage 70. This may be advantageous in reducing overheating of the profiling element 510, in particular, in embodiments in which the profiling element comprises a sensor device 521 or a laser sensor 530 located within a vacuum chamber 20.

[0172] While positioning the profiling element 510 on the sample stage 70, the profiling element 510 may be supported on a holder such as the holder 60, 60' discussed above. The holder 60, 60' may be a standard holder such as a sample holder known in the art, or it may be a holder referred to as the sensor holder 60' discussed above. Mechanical and / or thermal and / or electrical coupling of the profiling element 510 to the sample stage 70 may be achieved via the sensor holder 60' as discussed above. The sensor holder 60' may be optionally employed, for example, if the profiling element 510 is a laser sensor 530, or if the profiling element 510 is a sensor device 521 coated thereon with a laser-sensitive material 520. If the sensor device 521 is located far from the laser-sensitive material 520 and the profiling element 510 is made of the laser-sensitive material 520, a standard sample holder may be employed as holder 60.

[0173] The profiling element 510 may be supported on holders 60, 60' before being transported into the vacuum chamber 20. The profiling element 510 may then be transported into the vacuum chamber 20 while it is on holders 60, 60'. The profiling element 510 may be transported into the vacuum chamber 20 using a transport component, such as the transport rod discussed above. If the profiling element 510 is supported on holders 60, 60' during the measurement of the intensity profile (during step 101), then when holders 60, 60' are placed on the sample stage 70, the transport component may be mechanically coupled to and then mechanically uncoupled from holders 60, 60' before being inserted into the vacuum chamber 20 or load lock 30. Alternatively, holders 60, 60' may already be placed in the vacuum chamber 20, and the profiling element 510 may be placed on holders 60, 60' after the profiling element 510 has been inserted into the vacuum chamber 20.

[0174] The laser beam may operate in the profiling mode discussed above while the intensity profile of the laser beam is measured, i.e., during step 101. As discussed above, in profiling mode, the laser beam may irradiate the profiling element 510 at an energy lower than the energy suitable for performing ablation of the sample.

[0175] In exemplary embodiments, a laser beam is generated by a laser light source and can be shaped using a beam shaper, such as the beam shaper 420 discussed above. A reference position may be located downstream of the beam shaper 420 and upstream of the laser beam's focus. The reference position 300 may be located in the imaging plane of the beam shaper 420. In exemplary embodiments, the laser beam can be shaped from a substantially Gaussian incident laser beam into a top-hat intensity profile. The laser beam may be expanded before being shaped by the beam shaper 420. After being shaped by the beam shaper 420, the laser beam may be focused by an objective lens, such as the objective lens 450 discussed above. The laser beam may be generated, shaped, and directed using the laser beam assembly 40 discussed above. Further optical components may be employed to direct and shape the laser beam. For example, as shown in Figure 3, the laser beam may also optionally pass through a variable attenuator 430, a polarization adjustment optical system 435, and a second beam expander 440 which may be placed between the beam shaper 420 and the objective lens 450. The variable attenuator 430 may be used to reduce the beam power / energy. As shown in Figure 3, mirrors may be used to direct the laser beam.

[0176] The laser beam can optionally be generated outside the vacuum chamber 20, as shown in Figures 2 and 3, and then transmitted into the vacuum chamber 20 through a window, such as the window 25 discussed above.

[0177] The profiling element 510 may include the laser-sensitive material 520 or the laser sensor 530 discussed above. If the laser-sensitive material 520 is used as the profiling element 510, then during the measurement of the intensity profile of the laser beam, the laser-sensitive material will intersect with the laser beam at the reference position 300. If the profiling element 510 includes the laser sensor 530, then during the measurement of the intensity profile of the laser beam, the sensing surface 530a of the laser sensor 530 will intersect with the laser beam at the reference position 300.

[0178] When the laser-sensitive material 520 is employed as a profiling element 510, measuring the intensity profile of the laser beam may include detecting changes in the laser-sensitive material 520 or radiation from the laser-sensitive material 520 in response to irradiation of the laser-sensitive material 520 with the laser beam. The above description of the laser-sensitive material 520 applies equally to the laser-sensitive material 520 employed in this method. Measuring the intensity profile of the laser beam may include detecting changes in the laser-sensitive material 520 or radiation from the laser-sensitive material 520 as a result of irradiation of the laser-sensitive material 520 with the laser beam, and correlating the detected changes or radiation with the intensity of the laser beam irradiating the laser-sensitive material 520.

[0179] If the laser-sensitive material 520 generates radiation in response to irradiation by a laser beam, measuring the intensity of the laser beam may include detecting the intensity of the radiation from the laser-sensitive material 520. As discussed above, the laser-sensitive material 520 may be configured to generate radiation in response to irradiation by a laser beam having an intensity proportional to the intensity of the laser beam irradiating it. Therefore, by detecting the intensity of the radiation from the laser-sensitive material 520, the intensity of the laser beam on the laser-sensitive material 520, and thus at the reference position 300, can be determined based on a proportional relationship. As discussed above, the generated radiation may be, for example, visible light.

[0180] If the laser-sensitive material 520 undergoes a detectable change in response to irradiation with a laser beam, measuring the intensity of the laser beam may include detecting the change in the laser-sensitive material 520 in response to irradiation with the laser beam. The detectable change may correlate with the intensity of the laser beam irradiating the laser-sensitive material 520. Optionally, the detectable change may be a visible change in the laser-sensitive material 520. The visible change may be a change in texture and / or color. Examples of laser-sensitive materials 520 undergoing visible changes that may be changes in texture and / or color are discussed above and apply equally to the method. Detecting the change in the laser-sensitive material 520 may include taking images of the laser-sensitive material 520 before and after irradiation with the laser-sensitive material 520, and then determining the change in the laser-sensitive material 520 by comparing the captured images.

[0181] Changes in the laser-sensitive material 520 or radiation from the laser-sensitive material 520 in response to irradiation of the laser-sensitive material 520 with a laser beam can be detected using a sensor device such as the sensor device 521 discussed above. The sensor device 521 may be a camera such as a CCD or CMOS camera, as discussed above. As discussed above, the laser-sensitive material 520 may be directly coated onto the sensing surface 521a of the sensor device 521. In such an arrangement, the sensor device 521 and the laser-sensitive material 520 coated thereon form a profiling element 510. Such an arrangement is illustrated in Figure 7 and may be employed in this manner. Alternatively, the sensor device 521 may be located remotely from the laser-sensitive material 520, i.e., separated from it. In such an arrangement, the profiling element 510 is the laser-sensitive material 520. If the sensor device 521 is located at a distance from the laser-sensitive material 520, the sensor device 521 may be positioned outside the vacuum chamber 20 so that it can receive radiation from the laser-sensitive material 520 through the window 26 or image the laser-sensitive material 520 during measurement of the intensity profile of the laser beam. This may be advantageous in reducing overheating on the sensor device 521 that could otherwise occur under vacuum conditions. Optionally, the measurement of the intensity profile of the laser beam may include imagering of the laser-sensitive material 520 or reflecting radiation from the laser-sensitive material 520 toward the sensing surface 521a of the sensor device 521 by a reflector, such as the reflector 522 discussed above. Such an arrangement is illustrated in Figure 4 and may be employed in this manner.

[0182] When a laser sensor 530, such as the laser sensor 530 discussed above, is employed as a profiling element 510, measuring the intensity of the laser beam may include detecting the intensity of irradiation by the laser beam using the laser sensor 530. The laser sensor 530 may be a camera, such as a CCD or CMOS camera, as discussed above. Such an arrangement is illustrated in Figure 6.

[0183] In embodiments employing a laser sensor 530 or a sensor device 521 coated on top of a laser-sensitive material 520, the laser sensor 530 or sensor device 521 may be positioned on the sample stage 70 during the measurement of the intensity profile as discussed above. The method may include transmitting power to the laser sensor 530 or sensor device 521 via the sample stage 70 during the measurement of the intensity profile. The sample stage 70 may be electrically coupled to a power source, such as the power supply 800 discussed above. As discussed above, the sample stage 70 may be positioned inside the vacuum chamber 20, and the power supply 800 may be positioned outside the vacuum chamber 20. The electrical connection between the sample stage 70 and the power supply 800 may be a fixed (i.e., permanent) electrical connection, such as a wired electrical connection, which may extend through a vacuum feedthrough 900 to avoid breaking the vacuum of the vacuum chamber 20. The laser sensor 530 or sensor device 521 may be electrically coupled to the sample stage 70 and, therefore, to the power supply 800 in a releaseable manner when the laser sensor 530 or sensor device 521 is placed on the sample stage 70. While the laser sensor 530 or sensor device 521 is turned on during the profiling step, heat may be transferred from the laser sensor 530 or sensor device 521 to the heat sink 71 in the sample stage 70 due to thermal coupling between the sample stage 70 and the laser sensor 530 or sensor device 521 on the sample stage 70.

[0184] The method may include a step of transmitting data from the laser sensor 530 or sensor device 521 during or after the step of measuring the intensity profile of the laser beam. Data transmission may be carried out wirelessly, for example, via Bluetooth or via a wired connection. The step of transmitting data from the laser sensor 530 or sensor device 521 may include transmitting data from the laser sensor 530 or sensor device 521 to the processing device 120 and / or controller 100 discussed above. The intensity profile may be generated by the laser sensor 530 or sensor device 521, and the data transmitted to the processing device 120 and / or controller 100 may include the generated intensity profile. Alternatively, the data transmitted from the laser sensor 530 or sensor device 521 to the processing device and / or controller 100 may include raw data acquired by the laser sensor 530 or sensor device 521. The processing device 120 and / or controller 100 may generate an intensity profile based on the raw data received from the laser sensor 530 or sensor device 521.

[0185] In embodiments where a laser sensor 530 or sensor device 521 is placed on the sample stage 70 during intensity profile measurement, data can be transmitted from the sensor device 521 or the laser sensor 530 via the sample stage 70 when the sensor device 521 or the laser sensor 530 is placed on it. The sample stage 70 may be electrically connected to the processing device 120 and / or controller 100, for example, via a wired connection. The laser sensor 530 or sensor device 521 may be electrically releasably coupled to the sample stage 70 and, therefore, to the processing device when the laser sensor 530 or sensor device 521 is placed on the sample stage 70. This releasable electrical coupling may be configured for data transmission.

[0186] During step 101, both data from the sensor device 521 or the laser sensor 530 and power to the sensor device 521 or the laser sensor 530 may be transmitted through the sample stage 70. Power transmission may be carried out via an electrical coupling between the sample stage 70 and the power supply 800, and via a releasable electrical coupling between the sample stage 70 and the laser sensor 530 or sensor device 521 on it. Data transmission may be carried out via an electrical coupling between the sample stage 70 and the processing device 120, and via a releasable electrical coupling between the sample stage 70 and the laser sensor 530 or sensor device 521 on it. The electrical coupling between the sample stage 70 and the processing device 120 and / or the controller 100 may be achieved using a wired connection, which may optionally include one or more pairs of twisted wires, as discussed above.

[0187] The laser sensor 530 or sensor device 521 may be positioned on the sensor holder 60' as discussed above. In such a position, the laser sensor 530 or sensor device 521 may be electrically and / or thermally coupled to the sample stage 70 via the sensor holder 60', while the sensor holder 60' is mechanically coupled to the sample stage 70.

[0188] In the context of apparatus 10, the releasable electrical and / or thermal coupling via the sensor holder 60' discussed above can be equally applied to the method. For example, releasable electrical coupling can be achieved by the use of electrical contacts that achieve electrical coupling when in direct contact with each other. As discussed above, releasable electrical coupling will be achieved when there is direct contact between the electrical contact of the sensor holder 60' described above as the holder electrical contact 610 and the electrical contact of the sample stage 70 described above as the stage electrical contact 710. The direct contact between the holder electrical contact 610 and the stage electrical contact 710 is achieved on the mechanical coupling (and thus their alignment) between the sensor holder 60' and the sample stage 70. For example, the stage electrical contact 710 is electrically connected to the power supply 800 and / or processing device 120 via a wired connection. For example, the holder electrical contact 610 is electrically connected to the upper laser sensor 530 or sensor device 521 via a wired connection.

[0189] As discussed above, a releasable thermal coupling can be achieved, for example, through direct contact between the heat sink 71 and the holder thermal coupling element 62. Direct contact is achieved through the mechanical coupling between the sensor holder 60' and the sample stage 70, and thus through their alignment.

[0190] As discussed above, in an advantageous embodiment employing the sensor holder 60', power supply to the sensor device 521 or laser sensor 530 and data transmission therefrom can only occur while the sensor holder 60', which supports the sensor device 521 or laser sensor 530 thereon, is mechanically coupled to the sample stage 70. This reduces unnecessary power consumption by the laser sensor 530 or sensor device 521 in the vacuum chamber 20 and the resulting overheating during periods when the sensor device 521 or laser sensor 530 is not positioned for use.

[0191] In embodiments employing a remote sensor device 521 from the laser-sensitive material 520, the sensor device 521 may be located outside the vacuum chamber 20 and thus directly electrically connected to the processing device 120, for example, via a wired connection between them, for data transmission to them. Placing the sensor device 521 outside the vacuum chamber 20 may be advantageous in reducing overheating of the sensor device 521. However, since the laser-sensitive material 520 will be located inside the vacuum chamber 20, the intensity profile will still be advantageously measured in situ.

[0192] During the step of measuring the intensity profile at the reference position 300, the laser beam intersects the profiling element 510 at the reference position 300. The surface of the profiling element 510 intersected by the laser beam lies within the profiling plane, and the angle between the profiling plane and the laser beam is a non-zero angle.

[0193] If the intensity profile generated during step 101 is initially defective due to misalignment between the beam profiling element 510 and the laser beam, or, for example, due to the beam profiling element 510, the relative positioning of the beam profiling element 510 and the laser beam can be adjusted before repeating the measurement of the laser beam intensity profile. Thus, by using the beam profiling element 510 to measure the laser beam intensity profile in situ, this enables live, real-time adjustment of the beam profiling element 510 and the optical components of the laser beam assembly 40 to achieve an accurate laser beam intensity profile.

[0194] Step 102 Once the intensity profile of the laser beam is measured, the method then includes the step of shaping the laser beam based on the measured intensity profile (step 102). The step of shaping the laser beam based on the measured intensity profile may include either (i) not adjusting the shape of the laser beam if the measured intensity profile is of the desired shape, or (ii) adjusting the shape of the laser beam if the measured intensity profile is not of the desired shape.

[0195] The shape of the laser beam may be configured during step 102 to achieve a substantially top-hat or flat-top intensity profile at the reference position 300. Thus, the step of configuring the shape of the laser beam based on the measured intensity profile may include either (i) not adjusting the shape of the laser beam if the measured intensity profile is substantially a top-hat or flat-top intensity profile, or (ii) adjusting the shape of the laser beam if the measured intensity profile is not substantially a top-hat or flat-top intensity profile.

[0196] The step of shaping the laser beam may include adjusting one or more optical elements configured to shape the laser beam. The adjusted optical elements may be beam shapers, which may be diffractive optical elements. This may be the beam shaper 420 discussed above, which is configured to convert a substantially Gaussian incident laser beam into a uniform intensity spot of any shape (top-hat beam profile), such as a rectangle, square, circle, or other shape.

[0197] Adjusting an optical element, such as a beam shaper 420, to shape a laser beam may include adjusting the position of the optical element in one or more directions perpendicular to the propagation of the laser beam. Adjusting an optical element to shape a laser beam may include adjusting the position of the optical element or by adjusting the tilt of the optical element. The beam shaper positioning mechanism and / or beam shaper tilting mechanism discussed above may be used for such adjustments.

[0198] The processing device 120 may determine, based on the measured intensity profile, whether and how an optical element, such as a beam shaper 420, should be adjusted to achieve a substantially desired intensity profile at the reference position 300. For example, a measured intensity profile that is non-uniform (non-flat-top intensity profile), or a measured intensity profile that is flat-top intensity profile but has an asymmetric tilt, can be corrected by adjusting the positioning and / or tilt of the optical element. The processing device 120 may, for example, transmit commands or input parameters to the controller 100 to control the positioning and / or tilt of the optical element and adjust the optical element to change the shape of the laser beam at the reference position 300. The commands or input parameters are generated based on the measured intensity profile.

[0199] Once the shape of the laser beam is configured based on the measured intensity profile, the intensity profile of the laser beam may optionally be measured again to verify whether the intensity profile at the reference position 300 now corresponds to the desired intensity profile. In other words, after performing step 102, step 101 can be repeated. If the measured intensity profile does not yet adequately correspond to the desired intensity profile, further adjustments can be made to the optical elements of the laser beam based on the further measured intensity profile. In fact, by measuring the intensity profile of the laser beam in situ, live (real-time) adjustments to the configuration of the laser beam can be made to ensure that the desired intensity profile of the laser beam is achieved at the reference position 300.

[0200] Step 103 After measuring the intensity profile of the laser beam at a reference position 300 and constructing the shape of the laser beam based on the measured intensity profile, the method may include ablating material from a portion of the sample surface (step 103). This step may be referred to as the sample ablation step. During the sample ablation step, a portion of the sample surface intersects with the laser beam at the reference position 300. In other words, the sample surface may intersect with the laser beam at the reference position 300. The portion of the sample surface 110 that intersects with the laser beam at the reference position 300 may be the target area of ​​the sample, i.e., the area of ​​the sample of interest. As discussed above, the plane of the sample surface that intersects with the laser beam is referred to as the sampling plane. The angle of the intersection between the laser beam and the sampling plane during the sample ablation step may be the same as the angle of the intersection between the laser beam and the profiling plane during the profiling step. The laser beam is used to carry out the sample ablation. A laser beam assembly 40 may be used to generate and direct the laser beam, as discussed above. The laser beam assembly 40 may operate in the ablation mode discussed above during the sample ablation step. Therefore, the energy of the laser beam at the reference position 300 may be higher during the sample ablation step than the energy of the laser beam at the reference position during the profiling step.

[0201] As discussed above, during the profiling step, the profiling element 510 intersects the laser beam at the reference position 300. After the profiling step and before the sample ablation step, the method may include moving the sample 110 and / or the profiling element 510, and / or redirecting the laser beam, during the sample ablation step, such that a portion of the sample surface (not the profiling element 510) intersects the laser beam at the reference position 300. In other words, the apparatus 10 can be reconfigured so that the laser beam no longer intersects the profiling element 510 at the reference position 300, but instead intersects the sample 110 at the reference position 300. As discussed above, the configuration of the apparatus 10 during the profiling step may be referred to as the profiling configuration, and the configuration of the apparatus 10 during the sample ablation step may be referred to as the sample ablation configuration.

[0202] The laser beam can be redirected so that the location of the reference position 300 in the apparatus 10 during the profiling step is different from the location of the reference position 300 in the apparatus 10 during the sample ablation step. For example, if a laser beam assembly 40 is employed, the positioning of the objective lens 450 can be adjusted to coordinate the direction of the laser beam and the positioning of the reference position 300.

[0203] For both the profiling step and the sample ablation step, it is preferable that the direction of the laser beam be maintained such that the reference position 300 is in the same location within the apparatus 10 and optionally within the vacuum chamber 20. In such an arrangement, the sample 110 and the profiling element 510 will be moved relative to the reference position 300 between the profiling step and the sample ablation step.

[0204] The sample 110 and the profiling element 510 may both be present simultaneously in the apparatus 10, optionally in the vacuum chamber 20, during the profiling step and the sample ablation step, but they may be moved relative to a reference position 300 between the profiling step and the sample ablation step such that the sample 110 is irradiated by the laser beam during the sample ablation step but not during the profiling step, and the profiling element is irradiated by the laser beam during the profiling step but not during the sample ablation step.

[0205] Alternatively, the profiling element 510 and the sample 110 may not be present in the vacuum chamber 20 simultaneously during the profiling step and / or the sample ablation step. For example, the profiling element 510 may be removed from the vacuum chamber 20 after the profiling step has been performed. The sample 110 may be inserted into the vacuum chamber 20 after the profiling step and before the sample ablation step. In such an arrangement, the reference position 300 may be in the same location in the vacuum chamber 20 during the profiling step and the sample ablation step. In such an arrangement, the location of the profiling element 510 in the vacuum chamber 20 during the profiling step will be the same as the location of the sample 110 in the vacuum chamber 20 during the sample ablation step.

[0206] If the sample 110 is not already present in the apparatus 10 or in the vacuum chamber 20 of the apparatus 10, the method may include transporting the sample 110 into the apparatus 10, optionally into the vacuum chamber 20 of the apparatus 10, before the sample ablation step. The sample 110 may be introduced into the vacuum chamber 20 via a load lock 30 to avoid breaking the vacuum in the vacuum chamber 20.

[0207] As discussed above, if a holder 60, 60' is used for the profiling element 510, the profiling element 510 may be removed from the vacuum chamber 20 together with its holder 60, 60', and the profiling element 510 may be replaced with a sample 110 which may be on the same or different holder 60, 60'. A transport element as discussed above may be used to move the sample 110 and / or the profiling element 510. For example, a transport element may be inserted into the vacuum chamber 20 via a load lock 30, mechanically coupled to a holder 60, 60' having the profiling element 510 on top, used to remove the holder 60, 60' from the vacuum chamber 20 via the load lock 30, and then mechanically uncoupled from the holder 60, 60' having the profiling element 510 on top. Optionally, the transfer element can then be mechanically coupled to holders 60, 60' having the sample 110 on top, and optionally move the holders 60, 60' having the sample on top into the vacuum chamber 20 via the load lock 30, and then, once the holders are inside the vacuum chamber 20, the transfer element can be mechanically discoupled from the holders 60, 60'. The transfer element can then be removed from the vacuum chamber 20.

[0208] The sample 110 may be supported on a sample stage, such as the sample stage 70 discussed above, during sample ablation. The method may include placing the sample 110 on the sample stage 70 in the vacuum chamber 20 before performing the sample ablation. The sample 110 may be supported on the sample stage 70 in the vacuum chamber 20 directly (i.e., without intervening features) or indirectly (i.e., with intervening features such as holders 60, 60').

[0209] Placing the sample 110 on the sample stage 70 may include adjusting the position of the sample stage 70 in the x, y plane and / or the z direction, and / or rotating the sample stage 70 about an axis in the z direction, and / or tilting the sample stage 70.

[0210] The location of the sample 110 on the sample stage 70 during the sample ablation step may be the same as the location of the profiling element 110 on the sample stage 70 during the profiling step. According to such an arrangement, the profiling element 510 may be removed from the sample stage 70 after the profiling step, and the sample 110 may be placed on the sample stage before the sample ablation step. According to such an arrangement, the reference position 300 will be the same location in the vacuum chamber 20 during the sample ablation step and the profiling step.

[0211] The sample 110 may be placed on the sample stage 70 at a location separated from the profiling element 510 on the sample stage 70, for example, at a location separated in the xy plane. In such an arrangement, the sample 110 and the profiling element 510 may be located on the sample stage 70 simultaneously. An example of such an arrangement is illustrated in Figure 5A. The distance between the profiling element 510 and the sample 110 may be such that the sample 110 can be irradiated by the laser beam without irradiating the profiling element 510, and vice versa. More specifically, the distance between the profiling element 510 and the sample 110 may be greater than the beamwidth of the laser beam at the reference position 300. According to such an arrangement, both the sample 110 and the profiling element 510 may be located on the sample stage 70 during the profiling step and the sample ablation step.

[0212] According to one embodiment in which both the profiling element 510 and the sample 110 are located on the sample stage 70 during the profiling step and the sample ablation step, the sample stage 70, the profiling element 510, and the sample 110 can be maintained in the same location within the apparatus 10 for the profiling step and the sample ablation step. The laser beam can be redirected so that the profiling element 510 intersects with the laser beam at a reference position 300 during the profiling step and the sample intersects with the laser beam at a reference position 300 during the sample ablation step.

[0213] According to an alternative embodiment in which both the profiling element 510 and the sample 110 are placed on the sample stage 70 during the profiling step and the sample ablation step, the reference position 300 can be maintained in the same location within the apparatus 10 during the sample ablation step. According to such an arrangement, the sample 110 and the profiling element 510 can be moved relative to the reference position 300 such that the profiling element 510 intersects the laser beam at the reference position 300 during the profiling step and the sample surface 110 intersects the laser beam at the reference position 300 during the sample ablation step. Optionally, the sample 110 and the profiling element 510 can be moved relative to the reference position 300 by the movement of the sample stage 70 supporting the sample 110 and the profiling element 510 relative to the reference position 300. For example, the sample stage 70 can be rotated around an axis in the z direction or translated in the xy plane. In such an arrangement, there is no relative movement between the sample 110, the profiling element 510, and the sample stage 70. The movement of the sample stage 70 can be achieved using the stage positioning mechanism discussed above. This can then be carried out without interrupting the vacuum conditions 20. Alternatively, the sample 110 and profiling element 510 can be moved relative to the reference position 300 and relative to the sample stage 70. For example, a manipulator can be used to move the sample 110 and profiling element 510. If holders 60, 60' are used to support the sample 110 and / or profiling element 510 on them, as discussed above, the movement of the sample 110 and profiling element 510 relative to the reference position 300 can be achieved by moving the holders 60, 60' relative to the reference position 300 and relative to the sample stage 70.

[0214] The laser beam may be turned off after measuring the intensity profile of the laser beam, or after shaping the laser beam until a portion of the sample 110 is positioned to intersect with the laser beam at a reference position 300.

[0215] Once the sample 110 is positioned such that a portion of the sample surface intersects with the laser beam at reference position 300, the laser beam can be turned on to perform sample ablation (step 103). As discussed above, the laser may operate in its ablation mode during step 103 such that the energy of the laser beam at reference position 300 is suitable for ablating the sample.

[0216] Advantageously, according to the method, the intensity profile of the laser beam is measured, and the shape of the laser beam is constructed based on its measured intensity profile at a position in the trajectory of the laser beam intersecting the sample surface during sample ablation (the position is the reference position 300). Thus, since the shape of the laser beam at the spot where sample ablation will be performed is precisely controlled, the crater resulting from the ablation is precisely generated according to the desired shape, which may be a top-hat shape, as discussed above. Precise control of sample ablation, and therefore precise control of the shape of the crater formed by the ablation, is advantageous for accurate depth profiling, as will be discussed in more detail below.

[0217] Optionally, the method may include adjusting the laser beam parameters according to the material of the sample before sample ablation is performed. For example, the laser beam may be adjusted to ablate more material more quickly or to reduce damage to the surface composition. Different sample materials may require lower laser beam energy for ablation and / or may be more easily damaged by longer pulses and / or multiple pulses of different frequencies.

[0218] Step 104 Once sample ablation is performed (step 103), the method may include performing spectroscopic or microscopic analysis of at least a portion of the ablated portion by directing an imaging beam to the ablated portion (step 104). This step may be referred to as the analysis step. This step may include directing the imaging beam to the ablated portion along a trajectory in the instrument. Thus, during the analysis step, the imaging beam is directed to a new sample surface created by sample ablation. During the analysis step, the ablated portion may intersect the imaging beam at an imaging position in the trajectory of the imaging beam. The imaging position may be, for example, the focal point of the imaging beam. Thus, during the analysis step, the imaging beam may be focused on the ablated portion. Alternatively, the imaging position may be, for example, a fixed non-zero distance from the focal point, where the fixed distance is set by the user and / or a predetermined distance.

[0219] The imaging beam can be generated using the imaging beam source of the imaging beam assembly 50. The type of analysis performed will depend on the type of imaging beam, analyzer 80, and detector 90 used, as discussed above. In spectroscopic analysis, electrons and / or ions generated as a result of the interaction of the imaging beam with the ablated surface may be received by the analyzer 80 and detector 90, and their energy and / or intensity may be measured to determine the chemical composition of the ablated surface. In microscopic analysis, the energy of electrons and / or ions may not be measured; rather, the position and / or intensity of electrons and / or ions may be measured, for example, in TEM or SEM analysis, to determine a microscopic image of the ablated surface.

[0220] Preferably, the spot size of the imaging beam on the ablated portion is smaller than the size of the ablated portion. The beamwidth of the imaging beam at the imaging position may be smaller than the diameter of the ablated portion. The imaging beam may illuminate a portion of the area of ​​the ablated portion (the illuminated portion has a smaller area than the total area of ​​the ablated portion). Alternatively, if the imaging beam illuminates an area larger than the area of ​​the ablated portion, the imaging beam may be incident on the edge or sidewall of the ablated portion. This may cause electrons / ions originating from the edge or sidewall to be emitted and analyzed in addition to electrons / ions emitted from the surface to be investigated. These electrons / ions from the edge or sidewall may be from a different chemical composition than the crater surface to be investigated, and therefore may cause inaccuracies in the measurement. The imaging beam may be directed to center on the ablated portion (crater) formed by the ablation step. Ideally, the ratio of crater width to the diameter of the spot size at the imaging location may be at least 3:1, or at least 4:1, or at least 5:1.

[0221] In an exemplary embodiment, the imaging beam may be an X-ray beam, and the analyzer 80 and detector 90 may be configured to measure photoelectrons emitted from the ablated surface so that the spectroscopic analysis performed in step 106 is XPS. In an alternative exemplary embodiment, the imaging beam may be an electron beam, and the analyzer 80 and detector 90 may be configured to measure Auger electrons emitted from the ablated surface so that the spectroscopic analysis performed in step 106 is AES. In an alternative exemplary embodiment, the imaging beam may be a UV beam, and the analyzer 80 and detector 90 may be configured to measure photoelectrons emitted from the ablated surface so that the spectroscopic analysis performed in step 106 is UPS. In an alternative exemplary embodiment, the imaging beam may be an electron beam, and the analyzer 80 and detector 90 may be configured to measure electrons so that the spectroscopic analysis performed in step 106 is electron microscopy.

[0222] The intersection of the imaging beam and the ablated portion of the sample at the imaging position during the analysis step can be achieved without moving the sample 110. In such an arrangement, the laser beam and the imaging beam will be aligned with each other. The alignment of the imaging beam and the laser beam may be performed before the sample ablation step. The alignment of the imaging beam and the laser beam may be such that the imaging position and the reference position coincide. Such an arrangement is shown in Figure 10 and illustrated in Figure 12. This configuration will be discussed in more detail below.

[0223] Alternatively, if the imaging beam and the laser beam are not aligned with each other, and therefore the imaging position does not coincide with the reference position, the method may include moving the sample 110 between the sample ablation step and the analysis step such that the sample 110 moves from the reference position 300 to the imaging position where it intersects with the laser beam. In other words, the method may include moving the sample 110 after the sample ablation step and before the analysis step, relative to the reference position 300 and relative to the imaging position. Such configurations are shown in Figure 11 and illustrated in Figure 13. This configuration will be discussed in more detail below.

[0224] The sample ablation and analysis steps (steps 103 and 104) may be repeated to construct compositional information on the layers of sample 110, as shown in step 105. The performance of sample ablation and subsequent analysis may be referred to as an ablation and analysis cycle. Each cycle, including the step of ablating further material from a portion of the sample surface (i.e., ablating further material from the ablated portion), performs spectroscopic or microscopic analysis of at least a portion of the further ablated portion. Thus, each cycle results in the formation and analysis of deeper craters. In step 106, a compositional depth profile may be generated or calculated based on the compositional information of each layer. The depth profile may be quantitative.

[0225] During sample ablation, laser-induced periodic surface structures (LIPSS) may develop on the sample surface. However, changes in the linear polarization direction of the laser beam by using a polarization adjustment optical system during or between sample ablation steps can minimize the possible ripple morphology. Therefore, the method may include incremental or continuous rotation of the angle of the linearly polarized laser beam during or between sample ablation steps. Alternatively, the method may include conversion of the linearly polarized beam to a beam with circular or elliptical polarization. Sample rotation, polarization rotation, and / or polarization conversion can reduce LIPSS, thereby reducing the roughness of the bottom of craters formed during ablation and / or enabling the achievement of deeper depth profiles. For example, between each step of sample ablation, or between each laser pulse if a pulsed laser is used for sample ablation, the polarization plane of the sample surface 110 and / or the laser beam may be rotated, for example, 55 degrees. The degree of rotation between each laser pulse can be selected to effectively suppress LIPSS formation, and this can be a rotation of 10 to 80 degrees, for example, 40 to 70 degrees, or 55 degrees. The rotation can be centered on an axis parallel to the z-direction. Alternatively, the laser beam can be converted to elliptical or circular polarization to suppress LIPSS formation.

[0226] Exemplary embodiments of the method are shown in Figures 10 and 11, and in Figures 12 and 13, respectively.

[0227] The method shown in Figure 10 is an exemplary embodiment of the method in Figure 9. Steps 201, 202, 203, 204, 205, and 206 in Figure 10 correspond to steps 101, 102, 103, 104, 105, and 106 in Figure 9, respectively, which have been discussed above and will not be described again here to avoid repetition. The method in Figure 10 optionally requires an additional step of aligning the imaging beam and the laser beam (step 201a). The laser beam and the imaging beam can be aligned such that the imaging beam may coincide with the laser beam at reference position 300. In other words, the imaging beam can be aligned with the laser beam such that the imaging beam and the laser beam intersect at reference position 300. In particular, the imaging beam can be aligned with the laser beam such that the imaging position coincides with reference position 300. When the laser beam and the imaging beam are aligned relative to each other, the point in the device where the reference position of the laser beam and the imaging position of the imaging beam coincide can be called the coincidence point.

[0228] The beamwidth of the imaging beam at the imaging position and the beamwidth of the laser beam at the reference position 300 may not be the same. Optionally, the beamwidth of the imaging beam at the imaging position may be smaller than the beamwidth of the laser beam at the reference position 300. The step of aligning the imaging beam and the laser beam may include controlling the spot size of the imaging beam at the imaging position to be similar to or smaller than the spot size of the laser beam at the reference position 300.

[0229] According to the method in Figure 10, the step of aligning the imaging beam and the laser beam is optionally performed before the sample ablation step and the analysis step (steps 203, 204), and optionally also before the profiling step (step 201). In a particularly advantageous embodiment of the method in Figure 10, the imaging beam and the laser beam may be aligned by using a profiling element 510. The laser beam may be directed so that the profiling element 510 intersects with the laser beam at a reference position 300. The imaging beam may be directed so that the profiling element 510 intersects with the imaging beam at the imaging position. The alignment step may include detecting the illumination of the profiling element 510 by the imaging beam and / or the illumination of the profiling element 510 by the laser beam. In particular, the alignment step may include detecting the illumination area of ​​the profiling element 510 by the imaging beam and detecting the illumination area of ​​the profiling element 510 by the laser beam. The direction of the imaging beam and / or laser beam can be adjusted based on the detected areas of irradiation of the profiling element 510 by the laser beam and the detected areas of irradiation of the profiling element 510 by the imaging beam. The direction of the imaging beam and / or laser beam can be adjusted so that the irradiation area of ​​the profiling element 510 by the laser beam at least overlaps, preferably completely overlaps, and preferably is located at the center of the irradiation area of ​​the profiling element 510 by the imaging beam.

[0230] During step 201a, which may be referred to as the mutual alignment step, the imaging beam may be generated and directed using the imaging beam assembly 50 discussed above. The laser beam may be generated and directed using the laser beam assembly 40 discussed above. The energy of the laser beam during mutual alignment may be lower than the energy of the laser beam during the sample ablation step. For example, the energy of the laser beam during mutual alignment may be less than 100 μJ. The energy of the laser beam in the ablation mode may vary depending on the required material and ablation capacity, such as 10 nJ to 2000 μJ, or more preferably 50 to 1000 μJ.

[0231] The profiling element 510 may be illuminated simultaneously or sequentially by the imaging beam and the laser beam during step 201a. For example, if the illumination of the profiling element 510 by the imaging beam can be detected independently of the illumination of the profiling element 510 by the laser beam, the laser beam and the imaging beam may be directed simultaneously onto the profiling element 510 during step 201a. If the illumination of the profiling element 510 by the imaging beam cannot be detected independently of the illumination of the profiling element 510 by the laser beam, the laser beam and the imaging beam may be directed sequentially (and in any order) onto the profiling element 510 during step 201a.

[0232] In the exemplary embodiment of Figure 10, the step of aligning the imaging beam and the laser beam (step 201a) is optionally performed before the profiling step (before step 201). However, the step of aligning the imaging beam and the laser beam may alternatively be performed after the profiling step (after step 201), and optionally after the step of shaping the laser beam based on the measured intensity profile (after step 202). In such arrangements, during the step of aligning the imaging beam and the laser beam, the imaging beam can be aligned to the reference position 300 by detecting the illumination of the profiling element 510 by the imaging beam, in particular by detecting the illumination area of ​​the profiling element 510 by the imaging beam. In such arrangements, it is not necessary to detect the illumination of the profiling element by the laser beam during the step of aligning the imaging beam and the laser beam, because the illumination area of ​​the profiling element 510 by the laser beam can be determined from the intensity profile generated in step 201. In such an arrangement, the laser beam can maintain its trajectory and the location of the reference position 300 within the apparatus 10 after the profiling step is performed, and the direction of the imaging beam can be adjusted during the alignment step to align the imaging position with the reference position 300.

[0233] The profiling element 510 employed in the method shown in Figure 10 may be sensitive to both the laser beam and the imaging beam. Examples of such profiling elements 510 are discussed above in the context of apparatus 10 and are applicable to this method.

[0234] As discussed above, if the profiling element 510 includes a laser-sensitive material 520, the laser-sensitive material 520 may be configured to undergo a detectable change and / or produce radiation in response to irradiation with an imaging beam. Optionally, the detectable change and / or radiation resulting from irradiation with an imaging beam may be distinguishable from the detectable change and / or radiation resulting from irradiation with a laser beam.

[0235] The same sensor device, such as sensor device 521, may be used to detect changes in the laser-sensitive material 520 and / or radiation from the laser-sensitive material 520 resulting from irradiation with a laser beam for the profiling and alignment steps, and to detect changes in the laser-sensitive material 520 and / or radiation from the laser-sensitive material 520 as a result of irradiation with an imaging beam for the alignment steps. As discussed above, sensor device 521 may have the laser-sensitive material 520 coated thereon, or may be located remotely from the laser-sensitive material 520, as discussed above. Alternatively, sensor device 521 may be used to detect changes in the laser-sensitive material 520 and / or radiation from the laser-sensitive material 520 resulting from irradiation with a laser beam for the profiling and alignment steps, and further sensor devices may be used to detect changes in the laser-sensitive material 520 and / or radiation from the laser-sensitive material 520 as a result of irradiation with an imaging beam. Further sensor devices may be located remotely from the laser-sensitive material 520, if employed.

[0236] If the profiling element 510 includes a laser sensor such as the laser sensor 530 discussed above, the laser sensor 530 may be used to detect the illumination of its sensing surface 530a by a laser beam and to detect the illumination of its sensing surface 530a by an imaging beam during the alignment step.

[0237] If the illumination of the profiling element 510 with the imaging beam and the illumination of the profiling element 510 with the laser beam are not performed simultaneously during the mutual alignment step, the laser beam may be turned off while the imaging beam is illuminating the profiling element 510, and the imaging beam may be turned off while the laser beam is illuminating the profiling element 510.

[0238] The method in Figure 9 explains that the laser beam can be redirected to change the location of the reference position 300 within the apparatus 10 between the profiling step (step 101) and the sample ablation step (step 102). The method in Figure 10 differs from the method in Figure 9 in that, according to the method in Figure 10, the reference position 300 must be in the same location within the apparatus 10 for the profiling step (step 101) and the sample ablation step (step 103). As a result, according to the method in Figure 10, between the profiling step and the sample ablation step, the sample 110 and the profiling element 510 are moved relative to the reference position 300 such that the sample 110 (not the profiling element 510) intersects the laser beam at the reference position 300. According to the method in Figure 10, the sample 110 is in the same location within the apparatus 10 for the sample ablation step (step 103) and the analysis step (step 104).

[0239] Figure 11 is an exemplary embodiment of the method of Figure 9, which is an alternative embodiment of the method of Figure 10. Steps 301, 302, 303, 304, 305, and 306 in Figure 11 correspond to steps 101, 102, 103, 104, 105, and 106 in Figure 9, respectively, and these are not described again here to avoid repetition. Figure 11 differs from the embodiment of Figure 10 in that the imaging beam and the laser beam are not aligned with each other. The imaging beam and the laser beam are directed so that the imaging position does not coincide with the reference position 300. The imaging position may be separated from the reference position by a fixed distance which may be predetermined and / or selected by the user. The imaging position may be separated from the reference position, for example, in the xy-plane and / or z-direction. The fixed distance may be greater than the beamwidth of the imaging beam at the imaging position and the beamwidth of the laser beam at the reference position 300, so that there is no overlap between the spot formed by the imaging beam at the imaging position and the spot formed by the laser beam at the reference position 300. Figure 11 differs from the embodiment in Figure 9 because it requires an additional step (304a) after the sample ablation step (after step 303) and before the analysis step (before step 304). Step 304a in Figure 11 requires the sample to be moved within the apparatus 10 between the sample ablation step (step 303) and the analysis step (step 104). The sample 110 intersects with the laser beam at the reference position 300 during the sample ablation step (step 304). The sample 110 is then moved relative to the reference position 300 during step 304a such that its ablated portion intersects with the imaging beam at the imaging position and the imaging position is moved away from the reference position 300. Next, spectroscopic or microscopic analysis is performed with the ablated portion of sample 110 intersecting the imaging beam at the imaging position.

[0240] The movement of the sample 110 in step 304a relative to the reference position 300 (and relative to the imaging position) can be achieved in the same way as the movement of the sample 110 discussed above. For example, the sample 110 can be moved by using a manipulator as discussed above, by using a transport element, by moving the holders 60, 60' that support the sample 110 if holders 60 / 60' are employed, and / or by moving the sample stage 70.

[0241] Step 305 is similar to Step 105, which involves repeating the steps of sample ablation and spectroscopic or microscopic analysis. However, Step 305 differs from Step 105 in that it additionally requires (i) movement of the sample such that the ablated portion of the sample intersects with the laser beam at reference position 300 before the ablation is repeated, and (ii) movement of the sample after further ablation has been performed such that the further ablated portion intersects with the imaging beam at imaging position before the spectroscopic or microscopic analysis of the ablated portion is repeated.

[0242] An exemplary implementation of steps 201-204 of the method in Figure 10, performed on apparatus 10, is schematically illustrated in Figure 12. An exemplary implementation of steps 301-304 of the method in Figure 11, performed on apparatus 10, is schematically illustrated in Figure 13. Steps of the method are separated by dashed lines. Steps are performed sequentially from the top to the bottom of the figure. Movement of components is illustrated using dashed arrows. Solid arrows extending from the laser beam assembly 40 and the imaging beam assembly 50 illustrate exemplary paths of the laser beam and imaging beam, respectively. The absence of an arrow extending from the laser beam assembly 40 indicates that the laser beam assembly 40 is turned off so that the laser beam is not adopted during that step. Similarly, the absence of an arrow extending from the imaging beam assembly 50 indicates that the imaging beam assembly 50 is turned off so that the imaging beam is not adopted during that step.

[0243] The exemplary paths of electrons and / or ions emitted by the sample during step 204 are shown using solid arrows from the sample 110 to the detector 90 and analyzer 80.

[0244] In the illustrative schematic diagrams of Figures 12 and 13, the profiling element 510 is placed on holders 60, 60' which may be the sensor holder 60' discussed above, and the sample 110 is optionally placed on each holder 60. The illustrated method optionally includes inserting the profiling element 510, placed on holders 60, 60', into the vacuum chamber 20 via the load lock 30, and placing the profiling element 510 together with holders 60, 60' on the sample stage 70 before the profiling step (step 201) is performed.

[0245] In the illustrative schematic diagrams shown in Figures 12 and 13, the reference position 300 optionally remains in the same location within the apparatus 10 during the execution of the method. The illustrated method optionally includes moving the profiling element 510 out of the vacuum chamber 20 via the load lock 30, and then inserting the sample 110 into the vacuum chamber 20 via the load lock 30 after the step of shaping the laser beam (after step 102) and before the sample ablation step (before step 103). The sample 110 is positioned on its holder 60, 60', during transport out of the vacuum chamber 20, and on its holder 60 during transport into the vacuum chamber 20. The laser beam assembly 40 and the imaging beam assembly 50 are turned off during the movement of the sample 110 and the profiling element 510.

[0246] As discussed above, the method of Figure 10, schematically illustrated in Figure 12, differs from the method of Figure 11, illustrated in Figure 13, in that it further includes a step of aligning the imaging beam and the laser beam (step 201a). The step of aligning the imaging beam and the laser beam is optionally performed before the profiling step (before step 201) in the schematic diagram of Figure 12. In the exemplary schematic diagram shown in Figure 12, the step of aligning the imaging beam and the laser beam optionally includes detecting the illumination of the profiling element 510 by the imaging beam, and then detecting the illumination of the profiling element 510 by the laser beam. However, the detection of illumination of the profiling element 510 by the imaging beam and the profiling element in step 201a can be performed in any order.

[0247] As discussed above, during method steps 201-206 of Figure 10 as illustrated in Figure 12, the reference position 300 remains in the same location within the apparatus 10. Optionally, as illustrated in Figure 12, the sample stage 70 also remains in the same location within the apparatus 10 during the execution of method steps 201-206. Thus, after step 202 and before step 203, the sample 110 is inserted into the vacuum chamber 20 and positioned on the sample stage 70 in the same location as the profiling element 510 on the sample stage 70 during step 201. The sample 110 remains in the same location on the sample stage 70 for the sample ablation step (step 203) and the analysis step (step 204). During the analysis step, the imaging beam is switched on to generate an imaging beam. The imaging beam is already aligned with the laser beam during the alignment step (step 201a), so the imaging position necessarily coincides with the reference position 300. Therefore, the imaging position inevitably coincides with the ablated portion of the sample 110 that remains in the same location within the apparatus 10 for the sample ablation and analysis steps (steps 203, 204).

[0248] The method of Figure 11, illustrated in Figure 13, differs from the method of Figure 10, illustrated in Figure 12, in that it does not include a step of aligning the imaging beam with the laser beam. Instead, the imaging beam is directed to a different location within the apparatus 10 relative to the laser beam. The method includes performing sample ablation using a laser beam intersected by the sample at a reference position 300 (step 303), and then moving the sample 110 so that the ablated portion of the sample 110 intersects with the imaging beam at the imaging position. For example, the reference position 300 is located away from the imaging position in the xy plane and / or z direction. After the sample ablation step and before the analysis step, the sample 110 may be moved in the xy plane and / or z direction, as shown in Figure 13. In the exemplary embodiment shown in Figure 13, the sample 110 is moved by moving the sample stage 70, specifically by translating the sample stage 70 in the xy plane.

[0249] As shown in Figure 13, when the sample 110 is moved so that its ablated portion intersects with the imaging beam at the imaging position, the imaging beam may be turned on, and microscopic and / or spectroscopic analysis may be performed by irradiating the ablated portion with the imaging beam (step 304).

[0250] Depth Profile Generation In steps 106, 206, and 306, where the spectroscopic technique employed is optionally AES or XPS, examples of how depth profiles may be generated are provided below and further described in WO2024 / 052232A1, which is incorporated herein by reference. Detectors 90 and 80 can receive and count the number (intensity) and energy of photoelectrons or Auger electrons emitted from the surface of the ablated partial sample 110 following excitation with an X-ray or electron imaging beam, respectively. The total electron intensity is plotted as a function of electron (binding or kinetic) energy. Quantification in electron spectroscopy is based on a direct relationship between the intensity of the photoelectron and / or Auger electron peaks and the molar fractional concentration of elements within the analysis depth. This relationship is described by equation (1), where I is the peak intensity, J is the photon flux, ρ is the concentration of an atom or ion, σ is the electron emission cross-section, K is the spectrometer coefficient, and L is the electron decay length: JPEG2026108535000002.jpg13150

[0251] The radiation cross-section σ is the probability that photoelectrons or Auger electrons will be emitted from exposure to a high-energy source. The cross-section will vary depending on the element, electron orbital, and total angular momentum. The spectrometer coefficient K takes into account variations in detector performance between instruments and incorporates both the transfer function (i.e., the proportion of electrons transmitted through the detector as a function of kinetic energy) and the detector efficiency (i.e., the proportion of transmitted electrons that contribute to the detected signal). The inelastic mean free path describes the distance traveled by emitted electrons before inelastic scattering. However, equation (1) uses a more accurate term, decay length L, which corrects for the inelastic mean free path for elastic scattering, allowing the intensity radiated from a given depth in a given direction to be determined. Inelastic scattering results in electrons not contributing to the photoelectron and / or Auger electron peak intensity.

[0252] The contributions of each of the above factors (σ, K, L) to the photoelectron / Auger electron peak intensity of any particular peak in the spectrum are combined into a single term known as the sensitivity factor F, which allows for the determination of the relative proportion of that element at the depth of analysis (see equation (2) below). The sensitivity factor can be obtained from a library of theoretically determined, experimentally determined, or user-determined values. If library values ​​are determined for / with electron spectrometers having different transfer functions, corrections for those different transfer functions will be necessary.

[0253] Peak intensity is typically measured graphically as the integrated area of ​​photoelectron and / or Auger electron peaks after subtracting the background signal using a preferred method. Background C is calculated using different methods, including linear, Shirley, or Tougaard. Other methods exist for determining peak intensity, such as using peak height instead of peak area, or measuring the inter-peak differential spectrum as seen in electron-excited Auger spectroscopy.

[0254] Using equation (1), given a constant photon flux, the normalized peak intensity can be used to calculate elemental concentrations as atomic percentages, assuming the presence of a homogeneous mixture of elements within the analysis depth. Based on this assumption, the concentration of element A in a multi-element material is given by equation (2): JPEG2026108535000003.jpg13150

[0255] I and F represent the peak intensity and sensitivity factor of the elements detected in the spectrum (I A This is the peak intensity of element A, and F A(where is the sensitivity factor for element A). However, in the case of Auger electrons generated using an electron source, correction due to matrix effects is necessary. The sample is assumed to contain a homogeneous mixture of elements within the analytical depth for the quantification of photoelectron and Auger electron spectra, but if such an elemental distribution is known or expected to occur within the analytical depth, other methods can be used to give a more accurate description of the elemental distribution within the analytical depth.

[0256] Peak convolution can result from overlapping energy peaks or the presence of multiple chemical states. To quantify the different chemical states in such cases, peak fitting is necessary to separate the peak intensity contributions from the various components present, and then quantify them separately. The binding / kinetic energies of elements for different chemical states are determined by recording standard spectra of such materials with known compositions, or from available spectroscopic libraries.

[0257] To construct a depth profile, electron spectroscopic spectra are recorded from the surface of the ablated portion of sample 110 following each laser ablation cycle. The spectra are quantified, and the chemical composition is determined based on equation (2). For the surface on which the electron spectrum is recorded and for each cycle / depth, the fractional composition of each element or elemental chemical state is plotted as a function of the number of laser ablation cycles or depth. The conversion of cycle count to depth can be performed by measuring the depth or through prior knowledge of the layer thickness.

[0258] Experimental data As discussed above, it is particularly advantageous to obtain a top-hat beam profile at reference position 300 and therefore ablate the sample surface using a laser beam that has a top-hat profile at the position where it is incident on the sample surface. This is evident when reviewing Figures 14A to 14E obtained by simulation. The simulations used to obtain Figures 14A to 14E employed the same multilayer sample having alternating layers of chromium and nickel and a silicon substrate. Structures that are repeatedly ablated to obtain craters are illustrated in Figures 14A and 14D. Structures that undergo repeated cycles of partial ablation and analysis were ablated using a laser beam and an imaging beam to obtain the depth profiles shown in Figures 14B, 14C, and 14E. The simulations used to obtain Figures 14A to 14E were obtained based on the assumption that the sample surface was at 90 degrees to the laser beam during ablation and at 90 degrees to the imaging beam during analysis. The laser beam is incident on the sample surface at the position mentioned above, which is the reference position 300 (i.e., they intersect), and the imaging beam is incident on the sample surface at the position mentioned above, which is the imaging position (i.e., they intersect).

[0259] Figure 14A shows continuous layer delamination forming a crater, which occurs when repeated sample ablation is performed using a laser beam with a Gaussian intensity profile at reference position 300. Figures 14B and 14C show depth profile plots obtained by repeated ablation and analysis cycles of the ablated portion, where sample ablation is performed using a laser beam with a Gaussian beam profile at reference position 300, as shown in Figure 14A. Figure 14B shows the near-optimal depth profile obtained when ablation is performed using a laser beam with a Gaussian intensity profile at reference position, and Figure 14C shows the suboptimal depth profile obtained when ablation is performed using a laser beam with a Gaussian intensity profile at reference position. The degradation in the quality of the depth profile in Figure 14C compared to Figure 14B is a result of the ratio of the laser beam spot size at reference position to the imaging beam spot size at imaging position. Figure 14B employs a larger ratio of the laser beam spot size at reference position to the imaging beam spot size at imaging position compared to Figure 14C. In Figure 14B, the laser beam spot size to imaging position is shown at the reference position where the ratio of the imaging beam spot size is 5:1, and in Figure 14C, the laser beam spot size to imaging position is shown at the reference position where the ratio of the imaging beam spot size is 2:1.

[0260] When selecting the spot size or beam width of the laser beam incident on a sample for ablation, there is a balance between achieving sufficient flux for ablation and achieving a desirable size ratio of the laser beam spot size to the spot size of the imaging beam incident on the sample. A smaller spot size increases the flux for ablation of the sample. However, it is desirable that the imaging beam has a smaller spot size at the imaging position than the laser beam spot size at the reference position 300 (i.e., so that the imaging beam illuminates an area smaller than the area of ​​the ablated portion). In particular, the spot size of the imaging beam at the imaging position should ideally be at least 5 times smaller than the laser beam spot size at the reference position 300. Adopting a smaller spot size for the imaging beam compared to the laser beam spot size on the sample is desirable to avoid the imaging beam being incident on the edges or sidewalls of the crater formed by ablation. An imaging beam incident on the edges or sidewalls can cause electrons / ions originating from the edges or sidewalls to be emitted and analyzed in addition to electrons / ions emitted from the surface to be investigated. These electrons / ions from the edges or sidewalls may originate from a different chemical composition than the crater surface to be investigated, and therefore can lead to inaccuracies in the measurement. Indeed, the effect of the ratio of the laser beam spot size at the reference position to the imaging beam spot size at the imaging position on the quality of the generated depth profile can be seen by comparing Figures 14B and 14C. It will be understood that the smaller the laser beam spot size, and therefore the smaller the crater formed during ablation, the more sensitive the depth profile quality will be to the alignment of the imaging beam to the center of the crater. Finally, while reducing the imaging beam spot size at the imaging position improves the quality of the generated depth profile, it should also be noted that reducing the imaging beam spot size increases the time required to image the ablated portion.

[0261] With this in mind, the inventors have found that by shaping the laser beam to form a top-hat or flat-top intensity profile at reference position 300, the spot size of the laser beam can be reduced and the flux increased without compromising the quality of the depth profile that can be generated or the time required to perform analysis of the ablated portion. In fact, by employing a laser beam with a top-hat intensity profile at reference position 300, this allows for the use of an imaging beam with a reasonable spot size at the imaging position and allows for some degree of misalignment of the imaging beam with respect to the center of the crater formed by ablation.

[0262] Figure 14D shows continuous layer delamination forming a crater, which occurs when repeated sample ablation is performed using a laser beam with a top-hat intensity profile at reference position 300. Figure 14E shows a depth profile plot obtained by repeated ablation and analysis cycles of the ablated portion, where sample ablation is performed using a laser beam with a top-hat intensity profile at reference position 300, as shown in Figure 14D.

[0263] Figure 14D shows that employing a top-hat beam profile at reference position 300 results in uniform removal of the sample material, leading to accurate depth profiles generated over at least 50 iterations (cycles). In fact, the depth profiles accurately determine that each chromium layer has 100% atomic concentration of chromium, each nickel layer has 100% atomic concentration of nickel, and the silicon substrate layer has 100% atomic concentration of silicon. Figures 14B and 14C show that employing a Gaussian beam profile at reference position 300 results in lower accuracy of the generated depth profiles. Accuracy decreases as further iterations (cycles) are performed. In fact, in further cycles of ablation and analysis, the analysis can be seen to detect a decrease in the atomic concentration of the relevant elements in that layer. For example, in Figure 14C, after 45 iterations (cycles), the detected atomic concentration of chromium is approximately 80%, when it should be 100%, and the detected atomic concentration of nickel is approximately 20%, when it should be 0%. Figure 14E shows the perfect depth profile expected according to the simulations performed, although the depth profile actually achievable may not be perfectly perfect. Nevertheless, it will be understood that a higher quality depth profile can be achieved without compromising the efficiency of the depth profile by employing a laser beam with a top-hat intensity profile at reference position 300, rather than a Gaussian profile at reference position 300.

[0264] The top-hat intensity profile shown in Figure 14D and used to obtain the depth profile in Figure 14E is achieved by optical elements such as beam shapers, but these optical elements are sensitive and require adjustment. Therefore, Figure 14 demonstrates the importance of determining and controlling the intensity profile of the laser beam at reference position 300 in order to produce an accurate depth profile. By measuring the intensity profile of the laser beam at reference position 300 in the apparatus 10, i.e., in situ, and by configuring the shape of the laser beam, any subsequent sample ablation and spectroscopic analysis can be optimized, thereby producing a more accurate depth profile. Typically, sample ablation and analysis may be performed on a sample under vacuum. It is particularly advantageous to employ the beam profiling element 510 discussed above to measure the intensity profile of a laser beam that the beam profiling element 510 can withstand vacuum conditions. This is because the beam profiling element 510 can be placed inside the vacuum chamber 20 for measuring the intensity profile of the laser beam without significantly contaminating the vacuum chamber 20, thereby enabling the intensity profile to be measured in situ without disrupting the vacuum.

[0265] Figures 15A–15C demonstrate the generation of a laser beam intensity profile by using a beam profiling element 510, which is a laser-sensitive material 520, in particular a phosphorescent material that fluoresces upon irradiation. The laser-sensitive material 520 intersects the laser beam at a reference position 300. The final intensity profile is represented as a heat map and is shown in Figure 15C. In Figures 15B and 15C, higher intensities are at the center of the profile, and the intensity decreases towards the outer edge of the profile. The arrangement shown in Figure 4 was employed to generate the intensity profile, but the vacuum chamber 20 was ventilated and open. Figure 15A is a raw image of the laser-sensitive material 520 fluorescing as a result of irradiation with the laser beam. The image was captured by a sensor device 521 positioned outside the vacuum chamber 20, as shown in Figure 4. The sensor device 521 employed was a CMOS camera. This raw image was processed by the sensor device 521 and / or the processing device 120 connected thereto to generate an intensity profile represented as a heatmap shown in Figure 15B, and for adjustment of the exposure of the sensor device 521, the intensity profile shown in Figure 15C was obtained. Figure 15D is the intensity profile of the laser beam represented as a heatmap generated using a profiling camera placed at reference position 300 instead of the laser-sensitive material 520. In Figure 15D, higher intensities are at the center of the profile, and the intensity decreases towards the outer edge of the profile. As can be seen by comparing Figure 15C with Figure 15D, the intensity profile generated using the laser-sensitive material 520 and the sensor device 521 is similar to the intensity profile generated by the profiling camera. Thus, this demonstrates that the laser-sensitive material 520 and the sensor device 521 can be advantageously used to measure the intensity profile of a laser beam.

[0266] Figures 16A–16D demonstrate the generation of a laser beam intensity profile by using a beam profiling element, which is a laser-sensitive material 520, in particular a phosphorescent material that fluoresces upon irradiation. Figures 16A–16D demonstrate the advantages of configuring optical elements used to shape the laser beam in-situ and in vacuum to achieve a top-hat intensity profile at a reference position 300, as described in steps 102, 202, and 302. The intensity profiles generated in Figures 16A–16D were achieved by the laser-sensitive material 520 intersecting the laser beam at a reference position 300 at an incidence angle of 43 degrees.

[0267] In Figures 16A and 16B, higher intensities are directed towards the left side of the profile, and the intensity decreases towards the upper right edge of the profile. The arrangement shown in Figure 4 was employed to generate the intensity profile. The vacuum chamber 20 was not ventilated because it was under ultra-high vacuum conditions. Figures 16A and 16C are initial raw images of the laser-sensitive material fluorescing as a result of irradiation with a laser beam. The images were captured by a sensor device 521 positioned outside the vacuum chamber 20, as shown in Figure 4. The sensor device 521 employed was a CMOS camera. The intensity profiles obtained by processing this raw image (using the sensor device 521 and / or processing device 120 connected thereto) are shown in Figures 16B and 16D, respectively.

[0268] Figure 16E shows the intensity profile, represented as a heatmap, captured by a profiling camera positioned at reference position 300 instead of the laser-sensitive material 520, but the profiling camera was not under vacuum conditions. The sensing surface of the profiling camera was positioned perpendicular to the laser beam. Figure 16E shows the precise intensity profile of the laser beam at reference position 300.

[0269] As can be seen by comparing FIGS. 16D and 16E, the use of profiling element 510, a laser-sensitive material disposed within vacuum chamber 20 together with sensor device 521 disposed outside vacuum chamber 20, generates an intensity profile similar to that of a profiling camera not under vacuum conditions. Thus, this demonstrates that the arrangement shown in FIG. 4 can be advantageously used to measure the intensity of a laser beam in-situ under vacuum conditions without breaking the vacuum.

[0270] When taking the raw images of FIGS. 16A and 16C, the laser beam was incident on laser-sensitive material 520 at an angle of approximately 43 degrees. As shown in FIG. 16B, the intensity profile generated based on the raw image of FIG. 16A had lower accuracy than the intensity profile generated based on the raw image of FIG. 16C, as shown in FIG. 16D. In fact, the intensity profile of FIG. 16E correlates more closely with the intensity profile of FIG. 16D than does the intensity profile of FIG. 16B. By measuring the intensity profile of the laser beam in-situ, the positioning of beam profiling element 510 (in this case, laser-sensitive material 520) and / or the optical elements of laser beam assembly 40 can be adjusted to improve the accuracy of the generated intensity profile. For example, in this case, the positioning and tilt of the beam shaper were adjusted based on the initial measured intensity profile of FIG. 16B before generating the more accurate intensity profile of FIG. 16D.

[0271] It should be noted that the raw image taken in FIG. 15A has a "halo effect" around the center of the raw image, which can affect the resulting intensity profile. This halo effect can be reduced by adopting a threshold to remove noise and / or lower-intensity radiation. This halo effect can also be reduced by appropriately attenuating the incident laser beam using a neutral density filter to reduce the low-level illumination of the phosphorescent material. For example, the halo effect was removed for FIGS. 16A and 16C.

[0272] FIG. 17A is a raw image captured by a laser sensor 530 disposed at a reference position 300. The laser sensor 530 is a CMOS camera. The laser sensor 530 is disposed on a sensor holder 60' within a vacuum chamber 20 as shown in FIG. 8C and under vacuum conditions during measurement of the intensity profile of the laser beam. The laser beam is incident on the laser sensor 530 at an angle of approximately 43 degrees. This raw image is processed by a sensor device 521 and / or a processing device 120 connected thereto to generate an intensity profile represented as a heat map shown in FIG. 17B. The sensor holder 60' enables the laser sensor 530 to function without overheating or gas emission as discussed above. The intensity profile has a higher intensity towards the lower left of the profile, and the intensity decreases towards the upper right edge of the profile. FIG. 17 demonstrates that it is possible to use a laser sensor in-situ and under vacuum conditions to accurately measure the intensity profile of a laser beam.

[0273] Embodiments of the present disclosure have been described above and illustrated in the drawings, but these are merely examples and are non-limiting. Those skilled in the art will understand that alternative examples are possible within the scope of the present disclosure.

[0274] All aspects and / or features disclosed herein can be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. In particular, the preferred features of the present disclosure are applicable to all aspects and embodiments of the present disclosure and may be used in any combination. Similarly, features described in non-essential combinations may be used separately (rather than in combination).

[0275] Aspects and / or features described in the context of apparatus 10 may be applicable to the methods described herein. Aspects and / or features described in the context of the methods may be applicable to the features of apparatus 10.

[0276] Where used herein, including in the claims, the singular form of a term is interpreted as including the plural form unless the context indicates otherwise, and vice versa. For example, unless the context indicates otherwise, a singular reference in the claims, such as "a" or "an" (e.g., separator or analyzer), means "one or more" (e.g., one or more separators or one or more analyzers). Throughout the description and claims of this disclosure, the words "comprise," "including," "having," and "contain," as well as variations of the words, such as "comprising" and "comprises" or similar, mean that the described characteristic includes additional characteristics that may follow and is not intended (and does not) exclude the existence of other components.

[0277] Any use of any example or illustrative language provided herein (such as "for instance," "such as," "for example," and similar language) is intended merely to better illustrate the invention and, unless specifically claimed, does not imply any limitation to the scope of this disclosure. No language herein should be construed as indicating any element not claimed to be essential to the practice of this disclosure.

Claims

1. A method for operating a spectroscopic or microscopic apparatus, wherein the method is The method involves measuring the intensity profile of a laser beam directed along a trajectory through the apparatus in a vacuum, wherein the intensity profile is measured at a reference position in the trajectory by irradiating a profiling element with the laser beam, and the profiling element intersects the laser beam at the reference position. Based on the measured intensity profile, the shape of the laser beam is configured, Methods that include...

2. The method according to claim 1, wherein the reference position is at a reference distance from the focal point of the laser beam.

3. The method according to claim 1 or 2, further comprising, after the step of shaping the laser beam based on the measured intensity profile, ablating a portion of the material from the surface of a sample by irradiating the portion with the laser beam.

4. The method according to claim 3, wherein, during the step of ablating material from a portion of the sample surface, the portion of the sample surface intersects the laser beam at the reference position.

5. The method according to claim 3 or 4, further comprising, after the step of ablating material from a portion of the surface of a sample, performing a spectroscopic or microscopic analysis of at least a portion of the ablated portion, wherein optionally the spectroscopic analysis includes X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, and / or laser stimulated destruction spectroscopy, and optionally the microscopic analysis includes electron microscopy (TEM or SEM).

6. The method of claim 5, further comprising: performing one or more further cycles of ablation and analysis after the step of performing a spectroscopic or microscopic analysis, each cycle comprising the steps of ablating further material from the portion of the sample surface, followed by performing a spectroscopic or microscopic analysis of at least a portion of the further ablated portion; and determining a depth profile of at least a portion of the composition of the ablated portion of the sample surface after performing the one or more further cycles, wherein optionally the depth profile is quantitative.

7. The method according to claim 5 or 6, wherein the step of performing a spectroscopic or microscopic analysis of at least a portion of the ablated portion includes directing an imaging beam to the ablated portion along a trajectory in the apparatus, during the step of performing the spectroscopic or microscopic analysis, the imaging beam intersects the ablated portion at an imaging position in the trajectory of the imaging beam, and optionally the imaging beam includes a UV beam, an X-ray beam, an electron beam, an ion beam, and / or a laser beam.

8. The method according to claim 7, further comprising aligning the imaging beam and the laser beam with respect to each other such that the imaging position coincides with the reference position.

9. The method according to any one of claims 1 to 8, wherein the step of shaping the laser beam includes shaping the laser beam such that it substantially achieves a top-hat or flat-top intensity profile at the reference position.

10. The step of forming the laser beam is configured to shape the laser beam. The method according to any one of claims 1 to 9, comprising controlling one or more optical elements.

11. The method according to claim 10, wherein the one or more optical elements include a diffractive optical element and / or a refractive optical element.

12. The profiling element includes a laser-sensitive material or a laser sensor, optionally the profiling element includes the laser-sensitive material coated on a sensor device, optionally the laser sensor or sensor device includes one or more cameras, optionally the laser-sensitive material, sensor device, and / or laser sensor are in an ultra-high vacuum The method according to any one of claims 1 to 11, which satisfies the (UHV) condition.

13. The method according to claim 12, wherein the profiling element includes a laser-sensitive material, and the step of measuring the intensity profile of the laser beam at the reference position includes detecting a change in the laser-sensitive material in response to irradiation of the laser-sensitive material by the laser beam or radiation from the laser-sensitive material, wherein optionally the intensity of radiation from the laser-sensitive material is proportional to the intensity of the laser beam irradiating it.

14. The method according to claim 12 or 13, wherein the laser-sensitive material includes a light-emitting material configured to emit photons in response to irradiation by the laser beam, optionally the light-emitting material is a phosphorescent or fluorescent material, and optionally the light-emitting material is an upshift anti-Stokes phosphor for converting infrared laser light into visible light.

15. The method according to any one of claims 8 to 14, wherein the step of aligning the imaging beam and the laser beam includes detecting the irradiation of the profiling element by the imaging beam and / or detecting the irradiation of the profiling element by the laser beam, and optionally, during the step of aligning the imaging beam and the laser beam, the profiling element intersects the laser beam at the reference position and intersects the imaging beam at the imaging position.

16. The method of claim 15, as dependent on any one of claims 13 to 15, wherein the profiling element includes the laser-sensitive material, the laser-sensitive material is configured to undergo a change or generate radiation in response to irradiation by the imaging beam, and / or (ii) the profiling element includes the laser sensor, the laser sensor is configured to detect irradiation by the imaging beam.

17. The method according to any one of claims 3 to 8, wherein, after the step of measuring the intensity profile, the method includes (i) positioning the sample and / or the profiling elements, and / or (ii) redirecting the laser beam, such that the portion of the sample surface intersects the laser beam at the reference position during the step of ablating material from a portion of the sample surface.

18. The method according to any one of claims 1 to 17, wherein the profiling element is placed on a sample stage during the step of measuring the intensity profile.

19. The method according to claim 18, wherein the sample stage is configured to absorb or dissipate heat generated by the profiling element when the profiling element is placed on the sample stage, and optionally the sample stage comprises a heat sink configured to receive heat generated by the profiling element when the profiling element is placed on the sample stage.

20. The sample is placed on the sample stage during the step of measuring the intensity profile. The method according to claim 18 or 19, as dependent on claim 17, further comprising, after the step of measuring the intensity profile, during the step of ablating at least a portion of the surface of the sample, (i) moving the sample and the profiling element relative to the reference position by moving the sample stage, and / or (ii) changing the direction of the laser beam to move the reference position relative to the sample and the profiling element, such that the portion of the surface of the sample intersects the laser beam at the reference position.

21. The method according to any one of claims 18 to 20, comprising: coupling the profiling element to the sample stage before the step of measuring the intensity profile is performed so that the profiling element is coupled to the sample stage during the step of measuring the intensity profile; and uncoupling the profiling element from the sample stage after the step of measuring the intensity profile is performed.

22. The method according to claim 21, wherein the bonding includes mechanically and / or electrically bonding the profiling element to the sample stage and / or thermally bonding it.

23. The method according to claim 22, wherein (i) the profiling element includes the laser sensor, and during the step of measuring the intensity profile, the laser sensor is electrically coupled to the sample stage in a manner that allows the sample stage to transmit power to the laser sensor, or (ii) the profiling element includes the laser-sensitive material coated on the sensor device, and during the step of measuring the intensity profile, the sensor device is electrically coupled to the sample stage in a manner that allows the sample stage to transmit power to the sensor device.

24. (i) The profiling element comprises the laser sensor, and the method further comprises transferring data from the laser sensor to a processing device when the laser sensor is electrically coupled to the sample stage, optionally the step of transferring data from the laser sensor to the processing device is carried out using a wired connection optionally comprising one or more pairs of twisted wires, or (ii) The profiling element comprises the laser-sensitive material coated on the sensor device, and the method further comprises transferring data from the sensor device to a processing device when the sensor device is electrically coupled to the sample stage, optionally the step of transferring data from the sensor device to the processing device is carried out using a wired connection optionally comprising one or more pairs of twisted wires.

25. The method according to any one of claims 22 to 24, wherein the profiling element is supported on a holder, and the mechanical and / or electrical coupling and / or thermal coupling to the sample stage is achieved via the holder.

26. The method according to claim 25, wherein the holder and / or the sample stage includes the wired connection, as is dependent on claim 24.

27. The method according to any one of claims 1 to 26, wherein the spectroscopic or microscopic apparatus comprises a vacuum chamber, and the trajectory of the laser beam is such that the reference position is located in the vacuum chamber during the step of measuring the intensity profile of the laser beam at a reference position in the spectroscopic or microscopic apparatus, and shaping the laser beam based on the measured intensity profile.

28. The trajectory of the laser beam is such that, during the steps of ablating a portion of the material from a portion of the sample surface by irradiating that portion with the laser beam, and performing spectroscopic analysis of at least a portion of the ablated portion, the reference position is positioned within the vacuum chamber. Any one of claims 3 to 8, wherein the sample is positioned within the vacuum chamber during the step of ablating material from at least a portion of the sample surface, and during the step of performing spectroscopic or microscopic analysis of at least a portion of the ablated portion. The method according to claim 27 when it is dependent on one of the paragraphs.

29. The method according to claim 27 or 28, comprising optionally moving the profiling element into the vacuum chamber via a load lock before the step of measuring the intensity profile is performed, and moving the profiling element out of the vacuum chamber after the step of measuring the intensity profile has been performed.

30. The laser beam is a pulsed laser beam, and optionally, the laser beam is The method according to any one of claims 1 to 29, comprising one or more pulses having a duration of 1 ns or less, or 1 ps or less, or 1 fs or less, which is optionally within the range of 1 ps to 1 fs.

31. The method according to any one of claims 1 to 30, wherein the laser beam is an IR laser beam, a visible laser beam, or a UV laser beam.

32. Spectroscopic or microscopic apparatus, Vacuum chamber and A laser beam assembly configured to generate and direct a laser beam along a trajectory passing through the vacuum chamber, A laser beam profiler configured to measure the intensity profile of the laser beam at a reference position in the orbit located within the vacuum chamber, wherein the laser beam profiler comprises a profiling element that intersects the laser beam at the reference position, A spectroscopic or microscopic apparatus comprising a laser beam assembly and a beam shaper configured to shape the laser beam based on a measured intensity profile.

33. The spectroscopic or microscopic apparatus according to claim 32, wherein the laser beam is configured to operate in an ablation mode for ablating material from a portion of the surface of a sample.

34. The spectroscopic or microscopic apparatus according to claim 32 or 33, further comprising an imaging beam assembly configured to generate and direct an imaging beam along a trajectory within the apparatus, wherein the imaging beam is optionally one or more of a UV beam, an electron beam, an ion beam, an X-ray beam, and / or a laser beam.

35. The spectroscopic or microscopic apparatus according to any one of claims 32 to 34, wherein the laser beam profiler includes a profiling element comprising a laser-sensitive material or a laser sensor, optionally configured such that the laser-sensitive material undergoes a change and / or generates radiation in response to irradiation by the laser beam, optionally comprising the laser beam profiler and a sensor device configured to detect the change in the laser-sensitive material or the radiation from the laser-sensitive material, and optionally comprising the profiling element comprising the laser-sensitive material coated on the sensor device.

36. The laser sensor or sensor device includes one or more cameras, and optionally the laser-sensitive material and / or the laser sensor and / or the sensor device are in an ultra-high vacuum. A spectroscopic or microscopic apparatus according to claim 35 that conforms to (UHV) conditions.

37. (i) The profiling element is the laser-sensitive material, configured to undergo a change or generate radiation in response to irradiation by the imaging beam, and / or (ii) The profiling element is the laser sensor, configured to detect irradiation by the imaging beam, the spectroscopic or microscopic apparatus according to claim 35 or 36.

38. The spectroscopic or microscopic apparatus according to any one of claims 35 to 37, wherein the laser-sensitive material is configured to generate radiation with an intensity proportional to the intensity of the laser beam irradiating it.

39. The spectroscopic or microscopic apparatus according to claim 38, wherein the laser-sensitive material includes a light-emitting material configured to emit photons in response to irradiation by the laser beam, optionally the light-emitting material being a phosphorescent or fluorescent material, and optionally the light-emitting material being an upshift anti-Stokes phosphor for converting infrared laser light into visible light.

40. The spectroscopic or microscopic apparatus according to any one of claims 35 to 39, wherein the profiling element includes the laser-sensitive material, and the laser beam profiler includes a reflector configured to reflect imaging of the laser-sensitive material or radiation from the laser-sensitive material.

41. A spectroscopic or microscopic apparatus according to any one of claims 32 to 40, further comprising a sample stage configured to support a sample.

42. The spectroscopic or microscopic apparatus according to claim 41, as dependent on any one of claims 35 to 40, wherein the sample stage is configured to support the profiling element.

43. The spectroscopic or microscopic apparatus according to claim 42, wherein the apparatus is configured to reconfigure the apparatus from a first apparatus configuration in which the profiling element intersects the laser beam at the reference position to a second configuration in which the sample intersects the laser beam at the reference position, by (i) moving the sample stage to optionally move the profiling element and / or the sample, and / or (ii) changing the direction of the laser beam.

44. The spectroscopic or microscopic apparatus according to claim 42 or 43, wherein the sample stage is configured to absorb or dissipate heat generated by the profiling element when the profiling element is supported by the sample stage, and optionally the sample stage comprises a heat sink configured to receive heat generated by the profiling element when the profiling element is supported by the sample stage.

45. (i) The profiling element includes the laser sensor, and the sample stage is configured to be electrically and releasably coupled to the laser sensor when the laser sensor is supported on the sample stage, and optionally the sample stage comprises an electrical coupling element configured to be electrically and releasably coupled to the laser sensor when the laser sensor is supported on the sample stage, and optionally the electrical coupling element is configured to transmit power to and / or data from the laser sensor, or (ii) The spectroscopic or microscopic apparatus according to claim 41, as dependent on any one of claims 36 to 40, or the spectroscopic or microscopic apparatus according to any one of claims 42 to 44, wherein the profiling element comprises the laser-sensitive material coated on the sensor device, the sample stage is configured to be electrically releasably coupled to the sensor device when the sensor device is supported on the sample stage, and optionally the sample stage comprises an electrical coupling element configured to be electrically releasably coupled to the sensor device when the sensor device is supported on the sample stage, and optionally the electrical coupling element is configured to transmit power to and / or data from the sensor device.

46. The spectroscopic or microscopic apparatus according to claim 45, wherein the electrically coupled element is configured to transmit power to the laser sensor or sensor device, and the apparatus further comprises a data connection configured to transmit data from the laser sensor or sensor device, wherein optionally the data connection is a wireless data connection.

47. The spectroscopic or microscopic apparatus according to claim 45 or 46, wherein the electrically coupled element includes a wired connection configured to transmit power to and / or data from the laser sensor or sensor device, and optionally the wired connection includes one or more pairs of twisted wires.

48. A spectroscopic or microscopic apparatus according to claim 41, as dependent on any one of claims 37 to 40, further comprising a holder configured to support the profiling element, wherein the holder is configured to be mechanically and releasably coupled to the sample stage, or a spectroscopic or microscopic apparatus according to any one of claims 42 to 47.

49. The spectroscopic or microscopic apparatus according to claim 48, as dependent on any one of claims 45 to 47, wherein the profiling element includes the laser sensor or the laser-sensitive material coated on the sensor device, and the sample stage is configured to be electrically and releasably coupled to the laser sensor or the sensor device via the holder when the holder is mechanically coupled to the sample stage.

50. The spectroscopic or microscopic apparatus according to claim 49, wherein the electrically coupled element is a stage electrically coupled element, the holder comprises a holder electrically coupled element electrically connected to the laser sensor or sensor device, the holder electrically coupled element is configured to be electrically releasably coupled to the stage electrically coupled element when the holder is mechanically coupled to the sample stage, and optionally, the holder electrically coupled element and the stage electrically coupled element are configured to transmit power to and / or data from the laser sensor or sensor device when the holder is mechanically coupled to the sample stage.

51. The spectroscopic or microscopic apparatus according to claim 50, wherein the stage electrical coupling element includes one or more stage electrical contacts, and the holder electrical coupling element includes one or more holder electrical contacts, wherein the stage electrical contacts are configured to directly contact the holder electrical contacts when the holder is mechanically coupled to the sample stage.

52. The spectroscopic or microscopic apparatus according to claim 50 or 51, wherein the holder electrical coupling element includes a wired connection configured to transmit power and / or data to the laser sensor or sensor device, and optionally the wired connection includes one or more pairs of twisted wires.

53. The spectroscopic or microscopic apparatus according to any one of claims 45 to 52, further comprising a processing device configured to receive data from the laser sensor or sensor device via the electrically coupled element and / or the data connection.

54. The spectroscopic or microscopic apparatus according to any one of claims 32 to 53, further comprising a vacuum chamber, wherein the laser beam assembly is configured to direct the laser beam such that the reference position is located within the vacuum chamber.

55. The spectroscopic or microscopic apparatus according to claim 54, in which the sample stage is mounted in the vacuum chamber, as described in any one of claims 41 to 53.

56. The spectroscopic or microscopic apparatus according to claim 54 or 55, wherein the laser beam assembly is positioned outside the vacuum chamber, and the vacuum chamber comprises a window configured to allow the transmission of the laser beam.

57. The spectroscopic or microscopic apparatus according to any one of claims 54 to 56, wherein the apparatus optionally comprises a transfer component for moving the profiling element in and out of the vacuum chamber via a load lock.

58. The spectroscopic or microscopic apparatus according to claim 57, as dependent on any one of claims 48 to 52, wherein the transfer component is optionally configured to move the holder in and out of the vacuum chamber via a load lock.

59. The spectroscopic or microscopic apparatus according to any one of claims 32 to 58, wherein the beam shaper includes one or more optical elements configured to shape the laser beam, optionally including a diffractive optical element and / or a refractive optical element, and optionally the beam shaper is configured to shape the laser beam based on a measured intensity profile to achieve a substantially top-hat or flat-top intensity profile at the reference position.

60. The spectroscopic or microscopic apparatus according to any one of claims 32 to 59, wherein the reference position is at a reference distance from the focal point of the laser beam.

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