Device and method for analyzing and / or processing a sample with a particle beam

Abstract

Device (100) for analyzing and / or processing a sample (102) with a particle beam (116), wherein the sample (102) has an electrically conductive layer (142), comprising: a particle beam delivery unit (114) for delivering the particle beam (116) onto a surface (118) of the sample (102), at least one electrode (148) which is arranged to be spaced apart from the surface (118) of the sample (102) and together with at least one section (150) of the electrically conductive layer (142) of the sample (102) to form at least one capacitor (152) with a pre-determined capacitance (C), and at least one potential source (154, 254) which is electrically connected to the at least one electrode (148) in order to set the at least one electrode (148) to a pre-determined electrical potential (U1, U2), wherein the pre-determined capacitance (C) is determined based on the pre-determined electrical potential (U1, U2) of the at least one electrode (148) and a pre-determined charge accumulation (Q) on the surface (118) of the sample (102) due to the provided particle beam (116).

Description

[0001] The present invention relates to a device and a method for analyzing and / or processing a sample with a particle beam.

[0002] Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out using a lithography system, which includes an illumination system and a projection system. The image of a mask (reticule) illuminated by the illumination system is projected by the projection system onto a substrate, such as a silicon wafer, coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection system. This transfers the mask structure onto the photosensitive coating of the substrate.

[0003] Driven by the pursuit of ever smaller structures in the fabrication of integrated circuits, EUV lithography systems are currently being developed that utilize light with wavelengths ranging from 0.1 nm to 30 nm, particularly 13.5 nm. Since most materials absorb light of this wavelength, such EUV lithography systems must employ reflective optics, i.e., mirrors, instead of the previously used refracting optics, i.e., lenses.

[0004] The mask (i.e., lithography mask) is used for a large number of exposures, which is why it is crucial that the mask is free of defects and contaminants. Therefore, lithography masks undergo extensive inspection for defects and contaminants. Attempts are then made to repair any defects found or to remove the contaminants. These defects and contaminants can be extremely small, ranging in size from a few nanometers. Consequently, instruments with very high spatial resolution are required for their analysis and removal.

[0005] Processing devices are known with which defective structures on the mask can be locally etched away using a particle beam-induced etching process, and missing structures on the mask can be added using a particle beam-induced deposition process. These include, for example, modified scanning electron microscopes.

[0006] Furthermore, processing devices are known with which individual particles can be selectively removed from a surface of the mask. Atomic force microscopes are used for this purpose, for example. A particle is picked up with a measuring tip of the atomic force microscope and removed from the mask surface, adhering to the measuring tip.

[0007] Both the particle beam-induced etching and deposition process and the removal of particles are usually monitored and supported by imaging techniques (e.g., taking pictures using a scanning electron microscope).

[0008] It is known that sample charging effects can significantly degrade the accuracy of a scanning electron microscope. In particular, the electron beam (primary beam) striking the sample surface and the secondary electrons ejected from the sample material can lead to charges on the sample surface. This can cause a previously electrically neutral sample to become electrically charged. The charge accumulations on the sample surface can generate an electrical potential that can deform (e.g., defocus) and deflect the primary beam. This impairs the positional accuracy of the primary beam. Furthermore, the electrical potential generated by the charge accumulations on the sample surface can also influence the emission of secondary electrons (e.g., their number and trajectories). Consequently, the image quality of a secondary electron-based image can also be significantly degraded.

[0009] Furthermore, in cases where an atomic force microscope is used, the electrical potential generated by charge accumulations on the sample surface can cause a discharge when the tip of the microscope approaches the sample. This can damage or destroy the tip and / or the sample.

[0010] EP 1 587 128 B1 proposes to arrange a shielding element very close to the processing position in a scanning electron microscope, so that the charging of the sample and the impairment of the primary beam by a charging of the sample are reduced.

[0011] Against this background, one object of the present invention is to provide an improved device and an improved method for analyzing and / or processing a sample with a particle beam.

[0012] According to a first aspect, a device for analyzing and / or processing a sample with a particle beam is proposed. The sample has an electrically conductive layer. Furthermore, the device comprises: a particle beam delivery unit for delivering the particle beam onto a surface of the sample, at least one electrode which is designed to be arranged at a distance from the surface of the sample and together with at least one section of the electrically conductive layer of the sample to form at least one capacitor with a pre-determined capacitance, and at least one potential source which is electrically connected to the at least one electrode in order to set the at least one electrode to a pre-determined electrical potential, wherein the pre-determined capacity is determined based on the pre-determined electrical potential of the at least one electrode and a pre-determined charge accumulation on the surface of the sample due to the provided particle beam.

[0013] The at least one capacitor, formed by the at least one electrode and the at least one section of the electrically conductive layer of the sample, allows electrical charges on the sample surface to be stored in the at least one capacitor. In other words, the sample is capacitively coupled to the at least one electrode, so that a voltage difference builds up and the charges on the sample surface can be stored in the region of the at least one capacitor.

[0014] This reduces and / or prevents the interference of the particle beam (primary beam) impacting the sample surface with charge accumulation on the sample surface. For example, deformation of the particle beam, such as defocusing, and deflection of the particle beam due to charge accumulation can be reduced and / or avoided. This improves the positional accuracy of the primary beam.

[0015] Capacitive coupling of the sample to at least one electrode can also reduce and / or prevent the interference of secondary particles with charge accumulation on the sample surface. For example, it can limit or prevent the influence on the release of secondary particles (e.g., secondary electrons) from the sample material (e.g., the number of released secondary particles) and / or their trajectories after release. This can, for instance, reduce temporal fluctuations in a detector signal generated based on secondary particles. Consequently, it minimizes interference with image information (e.g., topographic contrast) generated based on the detector signal.

[0016] This allows for precise control of the primary beam, and the primary and secondary beams are less susceptible to random and / or uncontrollable interference. This enables high spatial resolution, both in image acquisition, as in a scanning electron microscope, and in processing methods performed with the particle beam, such as particle beam-induced etching or deposition processes, ion implantation, and / or other structure-modifying processes.

[0017] The sample is, for example, a lithography mask for microlithography. The sample is, for example, an EUV mask for EUV lithography (EUV: "extreme ultraviolet," working light wavelengths in the range of 1–30 nm, especially 13.5 nm). The sample is, for example, a reflective lithography mask. The sample has, for example, structures (e.g., absorber structures). One structure size of the structures is, for example, in the range of 10 nm–10 µm.

[0018] The electrically conductive layer of the sample is, for example, a continuous electrically conductive layer. The sample has, for example, a principal extension plane. The electrically conductive layer of the sample extends, for example, over the entire principal extension plane of the sample.

[0019] The sample can have the electrically conductive layer on its surface. In other words, the electrically conductive layer of the sample can be the uppermost layer of the sample with respect to the particle beam delivery unit. In this case, the electrically conductive layer has an exposed surface upon which the particle beam strikes.

[0020] In other cases, a further layer, e.g., insulating or dielectric, can be arranged above the electrically conductive layer in relation to the particle beam delivery unit. In this case, the further layer has an exposed surface onto which the particle beam strikes. The thickness of the further layer is, for example, a few nanometers.

[0021] The particle beam delivery unit is, for example, positioned above the sample. The at least one electrode is, for example, configured to be positioned between the particle beam delivery unit and the sample. The at least one electrode is, for example, configured to be positioned above the top surface of the sample, on which the particle beam is delivered.

[0022] The at least one electrode is positioned at a distance from the surface of the sample. The at least one electrode is therefore also positioned at a distance from the electrically conductive layer of the sample.

[0023] In particular, the at least one electrode and the sample (e.g., the surface of the sample) are not in electrically conductive contact with each other. Furthermore, the at least one electrode and the electrically conductive layer of the sample are also not in electrically conductive contact with each other. In other words, the at least one electrode is electrically insulated from the sample (e.g., from the surface of the sample or from the electrically conductive layer of the sample). That is, only an insulator or a dielectric is located between the at least one electrode and the sample (e.g., the surface of the sample or the electrically conductive layer of the sample). One can also say that the at least one electrode is free from electrically conductive contact with the sample, and the sample is free from electrically conductive contact with the at least one electrode.

[0024] By arranging at least one electrode at a distance from the surface of the sample and from the electrically conductive layer of the sample, changes to the sample surface or the electrically conductive layer can be avoided.

[0025] The distance between the at least one electrode and the surface of the sample is, for example, 300 µm or less, 200 µm or less, 100 µm or less, 50 µm or less and / or 30 µm or less.

[0026] A dielectric is arranged between the at least one electrode, which forms a first plate of the at least one capacitor, and the at least one section of the electrically conductive layer, which forms a second plate of the at least one capacitor.

[0027] The dielectric, for example, has a vacuum. In a case where an insulating / dielectric layer is arranged above the electrically conductive layer, the dielectric has, for example, a vacuum and the insulating / dielectric layer.

[0028] The analysis of the sample with the particle beam includes, for example, image acquisition of the sample surface using the particle beam (primary beam). Secondary particles are then extracted from the sample material and detected. The apparatus includes, for example, a modified electron microscope.

[0029] Sample processing with a particle beam includes, for example, particle beam-induced etching processes, in which material is locally removed from the sample surface. Sample processing with a particle beam can also include particle beam-induced deposition processes, in which a material is locally deposited onto the sample surface. Similar locally activated processes using the particle beam, such as the formation of a passivation layer or the compaction of a layer, can also be included in sample processing.

[0030] The device can, for example, also include an atomic force microscope. In this case, impurities (e.g., particles, foreign bodies) can be removed from the sample using the atomic force microscope. The removal process can be monitored by capturing images of the sample's surface using the particle beam (e.g., with an electron microscope).

[0031] The particle beam consists of charged particles, such as ions, electrons, or positrons. The delivery unit is, for example, an electron column capable of providing an electron beam with an energy in the range of 10 eV to 10 keV and a current in the range of 1 µA to 1 pA. Alternatively, it can be an ion source providing an ion beam. The particle beam is preferably focused onto the sample surface, achieving, for example, an irradiation zone with a diameter in the range of 1 nm to 100 nm. The particle beam of charged particles can be manipulated by electric and magnetic fields, i.e., accelerated, steered, shaped, and / or focused. For this purpose, the delivery unit can include a number of elements configured to generate the corresponding electric and / or magnetic field.

[0032] The at least one electrode, for example, has one or more plate-shaped electrodes.

[0033] The pre-determined charge accumulation on the surface of the sample due to the provided particle beam is, for example, a charge accumulation predicted before commissioning of the device and / or before the start of an analysis or processing process of the sample with the device.

[0034] The pre-determined charge accumulation exhibits, for example, a pre-determined amount of charge and / or polarity of the charge (e.g., positive or negative charge) on the surface of the sample.

[0035] In embodiments of the first aspect, the device for analyzing and / or processing a sample with a particle beam comprises: a device for capturing an instantaneous potential of the sample, and a control device for regulating the electrical potential of at least one electrode, wherein the control device is configured to to determine a deviation of the recorded instantaneous potential of the sample from a target value of the potential of the sample, to determine a control variable based on the determined deviation, and to generate a control signal to control the potential source of at least one electrode based on the determined manipulated variable.

[0036] By (e.g., repeatedly) measuring the instantaneous potential of the sample, a change in the sample's potential can be determined. A change in the sample's potential can be caused, for example, by the particle beam applied to the sample. Furthermore, the potential change of the sample can be compensated for by controlling (i.e., feedback control) the electrode potential (i.e., the electrode voltage).

[0037] The device for sensing the instantaneous potential of the sample is, for example, configured to detect a signal change at one or more detectors of the particle beam delivery unit (e.g., a change in the offset voltage at an X-ray detector). Alternatively or additionally, the device for sensing the instantaneous potential of the sample includes, for example, a tip of an atomic force microscope and / or a special voltage balance. Alternatively or additionally, the device for sensing the instantaneous potential of the sample is, for example, configured to detect a change in the capacitance and / or displacement currents (e.g., moving electrodes and / or the addition of electrodes) of the at least one capacitor.Alternatively or additionally, the device for detecting the instantaneous potential of the sample includes, for example, at least one current measuring unit, wherein the potential source is electrically connected to the at least one electrode via the at least one current measuring unit in order to measure a current flowing between the potential source and the at least one electrode.

[0038] In embodiments of the first aspect, the device for analyzing and / or processing a sample with a particle beam comprises: One or more actuators configured to adjust the distance between the at least one electrode and the surface of the sample based on a pre-determined distance. For example, the one or more actuators are configured to move the at least one electrode relative to the sample so that the pre-determined distance to the sample surface is set.

[0039] For example, the device can also include multiple actuators configured to maintain a uniform distance between the at least one electrode and the surface of the sample. In other words, the multiple actuators can be configured to align the at least one electrode parallel to the surface of the sample (e.g., to eliminate any existing tilt between the at least one electrode and the surface of the sample).

[0040] In embodiments of the first aspect, the device for analyzing and / or processing a sample with a particle beam comprises: one or more distance sensors designed to detect an instantaneous distance between the at least one electrode and the surface of the sample, and one or more actuators configured to adjust the distance between the at least one electrode and the surface of the sample based on the detected instantaneous distance and a pre-determined distance.

[0041] This allows the pre-determined distance to be set. Furthermore, a collision between the at least one electrode and the sample surface can be prevented. This is particularly advantageous when the pre-determined distance between the at least one electrode and the sample surface is very small.

[0042] For example, the device can also include several distance sensors configured to detect any tilting between the at least one electrode and the surface of the sample. Furthermore, the device can also include several actuators configured to correct the detected tilting.

[0043] Each distance sensor may, for example, include a capacitive distance sensor (e.g., one or more additional electrodes, such as one or more additional electrodes that are smaller than the at least one electrode that is part of the at least one capacitor). A distance sensor may also, for example, include a laser interferometer and / or a confocal microscope.

[0044] The one or more distance sensors are attached, for example, to the sample stage or to a housing of the particle beam delivery unit using at least one holder.

[0045] The one or more distance sensors are attached, for example, to the same holder (e.g., electrode holder) to which the at least one electrode forming part of the at least one capacitor is attached. If, for example, the at least one electrode is attached to the sample stage using at least one electrode holder, then the one or more distance sensors can also be attached to the sample stage using the at least one electrode holder. Alternatively, if the at least one electrode is attached to a housing of the particle beam delivery unit (e.g., using another electrode holder), then the one or more distance sensors can also be attached to the housing using the at least one other electrode holder.

[0046] The one or more actuators are, for example, arranged on at least one holder that is attached to the sample stage or to a housing of the particle beam delivery unit. Consequently, the at least one holder can be adjusted with respect to its distance from the particle beam delivery unit or the sample by means of the one or more actuators. Additionally or instead, the one or more actuators can also be arranged on the sample stage itself, so that the sample stage is height-adjustable (i.e., adjustable with respect to its distance from the particle beam delivery unit).

[0047] For example, the device also includes a control and / or regulating device designed to to determine a control variable based on the measured instantaneous distance and the pre-determined distance between the at least one electrode and the surface of the sample, and to generate a control signal to control one or more actuators based on the determined manipulated variable.

[0048] This allows the distance between the at least one electrode and the surface of the sample to be adjusted even more precisely to the pre-determined distance (feedback control) or regulated to the pre-determined distance (feedback control).

[0049] According to one embodiment of the first aspect, the at least one electrode is arranged to be positioned at a pre-determined distance from the surface of the sample and / or from the electrically conductive layer of the sample, wherein the pre-determined distance defines a distance of the at least one capacitor. Furthermore, the at least one electrode and the at least one section of the electrically conductive layer of the sample are arranged parallel to each other and overlapping in an overlap region, wherein the overlap region defines a pre-determined area of ​​the at least one capacitor. In addition, the pre-determined distance and the pre-determined area of ​​the at least one capacitor define the pre-determined capacitance of the at least one capacitor.

[0050] In this context, a “distance of the at least one capacitor” refers in particular to a distance between the plates of the at least one capacitor (e.g., the distance between the at least one electrode, which forms a first plate of the at least one capacitor, and the at least one section of the electrically conductive layer, which forms a second plate of the at least one capacitor).

[0051] For example, the pre-determined distance is a distance between a surface of the at least one electrode facing the sample and the surface of the sample and / or a surface of the electrically conductive layer of the sample.

[0052] The pre-determined capacitance of the at least one capacitor is calculated, for example, using the following equation 1. C=ε0εRAd

[0053] Here, C denotes the capacitance, ε0 the electric constant of free space (ε0=8.854 e -12 As / Vm), εR the relative permittivity of the dielectric (for vacuum as the dielectric, ε applies) R = 1), A the pre-determined area of ​​the at least one capacitor and d the distance between the plates of the at least one capacitor (e.g. the distance between the at least one electrode, which forms a first plate of the at least one capacitor, and the at least one section of the electrically conductive layer, which forms a second plate of the at least one capacitor).

[0054] The surface area of ​​at least one capacitor is, for example, 0.200 m². 2 or less, 0.100 m 2 or less, 0.010 m 2 or less, 0.008 m 2 or less, 0.006 m 2 or less, 0.004 m 2 or less, 0.003 m 2 or less, 0.002 m 2 or less and / or 0.001 m 2or less. In addition to or instead of the aforementioned maximum sizes, the surface area of ​​the at least one capacitor can, for example, also be a minimum of 0.001 m². 2 have (minimum size).

[0055] As can be seen in equation 1 above, the pre-determined capacitance of the at least one capacitor depends not only on the pre-determined distance d and the pre-determined area A of the at least one capacitor, but also on the relative permittivity ε. R The relative permittivity ε depends on the dielectric material in the capacitor gap. R The dielectric constant is 1 for a vacuum as the dielectric, and can usually be neglected for very thin insulating layers.

[0056] According to a further embodiment of the first aspect, the at least one potential source is configured to provide a ground potential, and the pre-determined capacitance is determined based on the ground potential as a pre-determined electrical potential.

[0057] Because the at least one electrode is held at a ground potential by the potential source (e.g. a ground connection), a potential difference can build up between the at least one electrode and the sample (i.e. the plates of the at least one capacitor), which stores free charges on the surface of the sample.

[0058] A mass potential is, in particular, an Earth potential or a potential equal to zero.

[0059] For example, at least one electrode can be electrically connected to a housing of the particle beam delivery unit, so that a mass potential of the housing serves as the at least potential source.

[0060] According to a further embodiment of the first aspect, the at least one potential source is configured to provide a positive and / or negative potential, and the pre-determined capacitance is determined as a pre-determined electrical potential based on the corresponding positive or negative potential provided.

[0061] By setting the at least one electrode to a positive and / or negative potential (i.e., a non-zero potential) via the potential source, a larger potential difference can be generated between the at least one electrode and the sample (i.e., the plates of the at least one capacitor). Thus, a smaller capacitance of the at least one capacitor (e.g., a smaller area A and / or a larger distance d) is sufficient to store a specific amount of charge in the at least one capacitor.

[0062] The capacitance of the at least one capacitor can in particular be expressed as a function of the charge Q stored in the at least one capacitor and the potential difference U between the plates of the capacitor as the following equation 2. C=QU

[0063] Equation 2 shows that with a larger potential difference U between the at least one electrode and the sample (i.e., the plates of the capacitor), a smaller capacitance of the at least one capacitor is sufficient to store a certain amount of charge Q in the at least one capacitor. If a smaller capacitance of the at least one capacitor is sufficient, then, according to Equation 1, the area A of the at least one capacitor can be smaller and / or the distance d between the at least one capacitor can be larger.

[0064] In some embodiments, the device can be configured such that the distance between the at least one electrode and the sample (i.e., the plates of the at least one capacitor) is variably adjustable. In this case, the capacitance of the at least one capacitor can be set even after the device has been manufactured by adjusting the distance between the at least one electrode and the sample. The potential supplied by the potential source can then be selected depending on the set capacitance of the at least one capacitor.

[0065] In some embodiments, the device can be configured such that the area of ​​the at least one capacitor (i.e., the overlap area of ​​the at least one electrode and the electrically conductive layer of the sample) is variably adjustable by laterally displacing the at least one electrode relative to the sample or relative to the electrically conductive layer of the sample. In this case, the capacitance of the at least one capacitor can be adjusted even after the device has been manufactured. Similarly, the potential supplied by the potential source can be selected depending on the set capacitance of the at least one capacitor.

[0066] For example, the charge state of the sample can also be determined by changing the capacitance of at least one capacitor. For instance, the distance between at least one electrode and the surface of the sample can be increased (e.g., stepwise or continuously). Furthermore, the charge state of the sample can be detected during the change in distance, e.g., using an electric field probe and / or by recording the detector signal during image acquisition with an electron microscope. The positive and / or negative potential is, in particular, a potential that is not equal to a ground potential or not equal to zero.

[0067] The at least one potential source is, for example, a potential source for variably adjusting the provided potential.

[0068] In embodiments, the sample can be adjusted to a pre-determined sample potential by providing a pre-determined potential at the at least one electrode.

[0069] For example, the sample can be raised to a positive potential by applying a pre-determined potential to at least one electrode. If the particle beam is a beam of negatively charged particles, such as an electron beam, the positively charged sample can exert a braking effect on the particle beam. This can slow down the velocity of the negatively charged particles, such as the electrons, in the primary beam, allowing them to land on the sample surface with lower energy. In this case, the positively charged sample can act as an electrical immersion lens.

[0070] For example, the sample can be pre-set to a pre-determined sample potential at at least one electrode, which corresponds to (e.g., is the same as) the electrical potential of the tip of an atomic force microscope. When an atomic force microscope is used to analyze and / or process the sample, the tip of the microscope should have the same electrical potential as the sample when approaching and / or making contact with it. If the tip of the atomic force microscope is grounded, for example, then the sample potential must also be grounded. Otherwise, the sample will discharge abruptly, which can damage and / or destroy it.

[0071] According to a further embodiment of the first aspect, the device has a sample holder for holding the sample. Furthermore, the at least one electrode is attached to the sample holder, and / or the sample holder and the at least one electrode are configured to be moved together relative to the particle beam delivery unit for the purpose of analyzing and / or processing the sample.

[0072] This allows the at least one electrode to be attached, for example, to an existing structure of the device, namely the sample holder. Furthermore, the at least one electrode can be easily positioned in an edge region of the sample (e.g., a non-usable area of ​​the sample).

[0073] The sample holder may also include a sample table.

[0074] According to one embodiment of the first aspect, the at least one electrode is movably attached to the sample holder, so that, after the sample has been arranged on the sample holder, the at least one electrode can be moved at least partially over the sample as seen from the particle beam delivery unit.

[0075] This allows at least one electrode to be attached to the sample holder and yet, after the sample has been placed on the sample holder, to be positioned at least partially between the sample and the particle beam delivery unit.

[0076] For example, at least one electrode is attached to the sample holder in a swiveling and / or foldable manner, so that after the sample has been arranged on the sample holder, at least one electrode can be swiveled or folded at least partially over the sample.

[0077] According to a further embodiment of the first aspect, the surface of the sample has a usable area and a non-usable area. Furthermore, the at least one electrode is configured to be positioned, at least partially, above the non-usable area of ​​the sample, as seen from the particle beam delivery unit, such that an area above the usable area is free of the at least one electrode.

[0078] This allows the (e.g., entire) usable area of ​​the sample to be analyzed and / or processed with the particle beam, even though at least one electrode is partially located between the particle beam delivery unit and the sample.

[0079] The usable area of ​​the sample is, for example, a region of the sample that contains microstructures which are to be imaged onto a wafer in a microlithography process. The non-usable area of ​​the sample is, for example, a region of the sample that is free of such microstructures. The non-usable area of ​​the sample is, for example, a boundary region of the sample.

[0080] According to a further embodiment of the first aspect, the particle beam delivery unit has a housing and the at least one electrode is attached to the housing, and / or the at least one electrode is arranged in a fixed position relative to the particle beam delivery unit.

[0081] This allows at least one electrode to be attached, for example, to an existing structure of the device, namely the housing of the particle beam delivery unit.

[0082] The at least one electrode is attached to the housing of the particle beam delivery unit and / or fixedly positioned relative to the particle beam delivery unit in such a way that the particle beam can be delivered unimpeded from the particle beam delivery unit to the surface of the sample. The area between an outlet opening of the particle beam delivery unit and the surface of the sample is, in particular, free of the at least one electrode.

[0083] During analysis and / or processing, the sample is moved relative to the particle beam delivery unit and the at least one electrode to analyze and / or process different areas of the sample. For example, the device includes a sample holder configured to be moved relative to the particle beam delivery unit and the at least one electrode for the purpose of analyzing and / or processing the sample.

[0084] Because the at least one electrode is attached to the housing of the particle beam delivery unit and / or is fixed in position relative to the particle beam delivery unit, the at least one electrode can also be partially positioned above the usable area of ​​the sample from the perspective of the particle beam delivery unit.

[0085] Furthermore, at least one electrode can be made larger, thus providing a larger capacitor area. This allows for a capacitor with a larger capacitance.

[0086] According to a further embodiment of the first aspect, the at least one electrode, as seen from the particle beam delivery unit, has a ring shape, a circular ring shape, a ring shape with a cutout, a rotationally symmetric shape with respect to an undisplaced beam direction of the particle beam, a rectangular shape, and / or an angular ring shape.

[0087] According to a further embodiment of the first aspect, the device has a current measuring unit, wherein the potential source is electrically connected to the at least one electrode via the current measuring unit in order to measure a current flowing between the potential source and the at least one electrode.

[0088] By measuring the current flowing between the potential source and the at least one electrode over a period of time, the amount of charge on the surface of the sample can be determined as the integral of the measured current over time.

[0089] If the device for analyzing and / or processing the sample includes an atomic force microscope, then the sample's potential can be measured using a probe tip of the microscope. Furthermore, in combination with a variable voltage source at at least one electrode, the potential difference at the probe tip of the atomic force microscope can be reduced to zero to facilitate improved sample processing with the microscope.

[0090] According to a further embodiment of the first aspect, the particle beam delivery unit is set up to provide the particle beam with a predetermined particle beam current for a predetermined duration, and the determined charge accumulation is determined based on the predetermined particle beam current and the predetermined duration.

[0091] For example, the charge accumulation Q can be determined from the pre-determined particle beam current I and the pre-determined time duration Δt based on the following equations. As is known, current I equals charge dQ per time dI. I=dQdt

[0092] For a constant current over time, equation 3 can be reformulated as follows. I=QΔt Q=I⋅Δt

[0093] Equation 5 can be used to calculate the charge accumulation Q from the pre-determined particle beam flux I and the pre-determined time duration Δt.

[0094] As an example only, a maximum value of 50 pA can be assumed for the current I of the particle beam. For a time duration Δt (e.g., analysis time and / or processing time) of one hour (3600 seconds), this results in a charge Q on the surface of the sample of 180 nC, as shown in Equation 6. Q=I⋅Δt=50 pA⋅3600 s=180 nC

[0095] For example, the particle beam delivery unit is set up to provide the particle beam with a predetermined particle beam current of 5 nA or less, 1 nA or less, 500 pA or less, 100 pA or less, 50 pA or less, 40 pA or less, 30 pA or less, 25 pA or less, 20 pA or less, and / or 10 pA or less.

[0096] According to a further embodiment of the first aspect, the pre-determined capacitance is determined such that a potential difference between the at least one electrode and the at least one section of the electrically conductive layer of the sample is a factor of 10 smaller, a factor of 100 smaller, a factor of 200 smaller, a factor of 300 smaller, a factor of 500 smaller and / or a factor of 1000 smaller than an accelerating voltage of the particle beam delivery unit.

[0097] In other words, the pre-determined capacity is determined such that the energy of the particle beam corresponding to the potential difference between the at least one electrode and the at least one section of the electrically conductive layer of the sample is a factor of 10 smaller, a factor of 100 smaller, a factor of 200 smaller, a factor of 300 smaller, a factor of 500 smaller and / or a factor of 1000 smaller than the energy of the provided particle beam.

[0098] For example, the pre-determined capacitance is determined such that the potential difference between the at least one electrode and the at least one section of the electrically conductive layer of the sample is smaller by the said factor than the accelerating voltage of the particle beam delivery unit over the time of sample processing.

[0099] The acceleration voltage of the particle beam delivery unit is 500 V or less, 300 V or less, 100 V or less and / or 50 V or less, merely by way of example.

[0100] According to a second aspect, an arrangement is proposed which includes a device as described above and a sample.

[0101] According to a third aspect, a method for analyzing and / or processing a sample with a particle beam using a device as described above is proposed. The sample has an electrically conductive layer. Furthermore, the method comprises the following steps: a) Providing the particle beam on a surface of the sample, whereby a charge accumulation occurs on the surface of the sample, b) Setting at least one electrode, which is arranged at a distance from the surface of the sample, to a pre-determined electrical potential, wherein the at least one electrode together with at least one section of the electrically conductive layer of the sample forms at least one capacitor with a pre-determined capacitance, and the pre-determined capacitance is determined based on the pre-determined electrical potential of the at least one electrode and a pre-determined charge accumulation on the surface of the sample due to the provided particle beam, and c) Storing charges on the surface of the sample in the at least one capacitor.

[0102] Steps b) and c) are, for example, performed simultaneously.

[0103] The procedure may optionally include a sample unloading step. This unloading can be performed, for example, once before step a) or repeatedly during steps b) and c). It is also possible to interrupt step b) and unload the sample during the interruption.

[0104] The sample can be discharged, for example, using nitrogen. Alternatively, it can be discharged by changing the accelerating voltage of the particle beam delivery unit (reversing the secondary electron yield). Furthermore, the sample can be discharged using plasma generators.

[0105] According to one embodiment of the third aspect, the method has the following features before step b): Determining the charge accumulation on the surface of the sample, Determining a target value for the capacitance of at least one capacitor based on the determined charge accumulation, and Adjusting the determined capacitance of the at least one capacitor for the pre-determined electrical potential of the at least one electrode by adjusting a distance and / or an area of ​​the at least one capacitor, wherein the distance of the at least one capacitor is a distance of the at least one electrode to the surface of the sample and / or to the electrically conductive layer of the sample, and The area of ​​the at least one capacitor is an overlap region in which the at least one electrode and the electrically conductive layer of the sample, which are arranged parallel to each other, overlap.

[0106] The charge accumulation on the sample surface due to the supplied particle beam is also determined, for example, before step a). The charge accumulation on the sample surface is predicted, for example, before commissioning the device and / or before the start of an analysis or processing process of the sample with the device, based on planned settings of the particle beam delivery unit.

[0107] However, the charge accumulation on the surface of the sample due to the provided particle beam can also be determined during or after step a).

[0108] Determining the charge accumulation on the surface of the sample involves, for example, determining the amount of charge and / or the polarity of the charge accumulation (e.g., positive or negative charge).

[0109] The amount of charge on the surface of the sample is determined, for example, by measuring a current flowing between the potential source and at least one electrode over a period of time. The amount of charge on the surface of the sample can then be determined as the integral of the measured current over time.

[0110] For example, the device has a current measuring unit, wherein the potential source is electrically connected to the at least one electrode via the current measuring unit in order to measure a current flowing between the potential source and the at least one electrode.

[0111] According to another embodiment of the third aspect, the method has the following features before step b): Capturing an instantaneous electrical potential of the sample, and Control of the electrical potential of at least one electrode, wherein a deviation of the detected instantaneous electrical potential of the sample from a setpoint of the electrical potential of the sample is determined, a manipulated variable is determined based on the determined deviation, and the potential source of the at least one electrode is controlled based on the determined manipulated variable.

[0112] By (e.g., repeatedly) measuring the instantaneous potential of the sample, a change in the sample's potential can be determined. A change in the sample's potential can be caused, for example, by the particle beam applied to the sample. Furthermore, the potential change of the sample can be compensated for by controlling (i.e., feedback control) the electrode potential (i.e., the electrode voltage).

[0113] The term "one" here is not necessarily to be understood as restricting the number to exactly one element. Rather, it can also refer to multiple elements, such as two, three, or more. Similarly, every other counter used here should not be interpreted as restricting the number to the exact number stated. Instead, numerical deviations, both higher and lower, are possible unless otherwise specified.

[0114] The embodiments and features described for the first aspect apply accordingly to the second and third aspects, and vice versa.

[0115] Other possible implementations of the invention also include combinations of features or embodiments described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In such cases, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0116] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention will be explained in more detail below with reference to preferred embodiments and the accompanying figures. Fig. Figure 1 shows a schematic view of an embodiment of a device for analyzing and / or processing a sample with a particle beam according to one embodiment; Fig. 2 shows a partial view of a sample in cross-section according to one embodiment; Fig. Figure 3 shows an enlarged section from Fig. 1, where a charge accumulation on a surface of the sample is illustrated; Fig. 4 shows a view similar to Fig. 3, illustrating the storage of charge in a capacitor; Fig. Figure 5 shows an enlarged partial view from Fig. 4; Fig. 6 shows a similar view Fig. 3 and Fig. 4, wherein a capacitor according to a further embodiment is shown; Fig. Figure 7 illustrates a current measuring unit according to an embodiment, which is used in the devices of Fig. 1 and 2 to 6 can be used; Fig. Figure 8 illustrates the attachment of an electrode of the capacitor to a sample stage of the device. Fig. 1; Fig. Figure 9 illustrates the attachment of an electrode of the capacitor to a housing of a particle beam delivery unit of the device. Fig. 1; Fig. Figures 10 to 17 show different embodiments of the at least one electrode of the device. Fig. 1; Fig. Figure 18 shows a flow diagram of a method for analyzing and / or processing a sample with a particle beam according to one embodiment; and Fig. Figure 19 illustrates a control loop for regulating a potential of at least one electrode of the device. Fig. 1.

[0117] In the figures, identical or functionally equivalent elements have been labelled with the same reference symbols, unless otherwise indicated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

[0118] Fig. Figure 1 shows a schematic view of an embodiment of a device 100 for analyzing and / or processing a sample 102. The device 100 has a housing 104. An interior of the housing 104 is pressurized, for example, by a vacuum pump 106 to a residual gas pressure of 1–10 -10 mBar, e.g. 10 -5 - 10 -9mBar, evacuatable.

[0119] The device 100 is specifically designed for analyzing and / or processing samples 102 in the form of lithography masks. For example, the device 100 is a verification and / or repair tool for lithography masks, especially for lithography masks for EUV lithography (extreme ultraviolet).

[0120] Reference numeral 200 designates an arrangement comprising the device 100 and a sample 102.

[0121] The device 100 also includes, for example, a sample table assembly 108 with a sample table 110 for holding the sample 102. The sample table 110 is preferably held mechanically damped and / or decoupled from the housing 104 by means of a holding device 112 of the sample table assembly 108. The sample table assembly 108 can further include a positioning unit (not shown) by means of which the sample table 110 can be moved, for example, in the three spatial directions x, y, and z and, for example, about at least one axis (e.g., the z-axis). Fig. 1) is rotatable. For example, this allows the position of the sample stage 110 and thus of the sample 102 to be set with an accuracy of a few nanometers.

[0122] The device 100 further comprises a particle beam delivery unit 114 for delivering a particle beam 116 onto a surface 118 of the sample 102. The particle beam 116 is, in particular, a beam of charged particles, such as electrons or ions. Using the particle beam 116, the sample 102, e.g., the sample surface 118, can be examined (e.g., imaged) and / or processed (e.g., in a particle beam-induced etching or deposition process).

[0123] The particle beam delivery unit 114, for example, has an electron column 120. The electron column 120 includes an electron source 122 for providing the particle beam 116 in the form of an electron beam. The electron column 120 also includes one or more detectors 124. The following is shown only as an example. Fig. Figure 1 shows a ring detector 124. The one or more detectors 124 serve, for example, to detect secondary electrons 126 ( Fig. 3), which are backscattered from the sample 102. The electron column 120 preferably has its own vacuum housing 128 within the vacuum housing 104. The vacuum housing 128 is, for example, designed to maintain a residual gas pressure of 10 -7 mBar - 10 -10 The vacuum is evacuated to mbar. In this vacuum, the electron beam 116 travels from the electron source 122 until it exits the vacuum housing 128 through an opening 130 on its underside 132 and then falls onto the surface 118 of the sample 102.

[0124] However, the particle beam delivery unit 114 can also be configured – in addition to or instead of the electron beam 116 – to provide an ion beam. In this case, the device includes an ion source (not shown).

[0125] One or more additional detectors (in addition to or instead of the ring detector 124) may also be provided, e.g. for secondary electrons 126 (not shown).

[0126] The device 100 can optionally also include a gas supply unit 134. The gas supply unit 134 serves to supply process gases via a gas line 136 to the focal point of the particle beam 116 (e.g., electron beam) on the sample 102. The particle beam supply unit 114, e.g., the electron column 106, can, in conjunction with the supplied process gases, perform particle beam-induced processing (e.g., electron beam-induced processing, EBIP). This includes, in particular, the deposition of material onto and / or the etching of material from the sample 102.

[0127] The device 100 also has a control unit 138 which appropriately controls the particle beam supply unit 114, the sample table device 108 and / or the gas supply unit 106.

[0128] Fig. Figure 2 shows a partial view of a cross-section of an exemplary sample 102. The sample 102 in the example of Fig. 2 comprises a substrate 140 and an electrically conductive layer 142 arranged thereon. A dielectric layer 144 is also arranged on the electrically conductive layer 142. Sample 102, for example, has a principal extension plane G ( Fig. 10), which corresponds to an xy-plane in the figures. Furthermore, the electrically conductive layer 142 extends, for example, over the entire principal extension plane G. The sample 102 also exhibits, for example, microstructures (e.g., absorber structures) (in Fig. 2 not shown).

[0129] As in Fig. As illustrated in Figure 3, the particle beam 116 (primary beam) striking the surface 118 of sample 102 and the secondary electrons 126 thereby ejected from the sample material can lead to charge accumulation Q on sample 102 near the sample surface 118. This can cause a previously electrically neutral sample 102 to become electrically charged. The charge accumulation Q on the sample surface 118 can deform the primary beam 116 (e.g., defocus it) or deflect it from its intended position. This impairs the positional accuracy of the primary beam 116. Furthermore, charge accumulation Q on the sample surface 118 can also influence the ejection of the secondary electrons 126 (e.g., their number and trajectories 146). Consequently, the image quality of an image of sample 102, created using secondary electrons 126, can also be degraded. B. from detector 124 ( Fig. 1) can be detected, is reconstructed.

[0130] To reduce the influence of charge accumulations Q on the sample surface 118 on the primary beam 116 and the secondary beam 126, 146, the device 100 has at least one electrode 148 which is arranged at a distance d from the surface 118 of the sample 102, as shown in Fig. Figure 3 shows that the at least one electrode 148, together with at least one section 150 of the electrically conductive layer 142 of the sample 102, forms at least one capacitor 152. One capacitance of the capacitor 152 is designated with the reference numeral C.

[0131] Furthermore, the device 100 comprises at least one potential source 154, which is electrically connected to the at least one electrode 148. An electrical connection between the at least one potential source 154 and the at least one electrode 148 is provided in Fig. 3 is marked with reference numeral 156. A potential U1 is applied to at least one electrode 148 by the potential source 154. The potential source 154 is, in the example of Fig. 1 and Fig. 3 a ground connection that connects at least one electrode 148 to a ground potential U M holds (U1 = U M ).

[0132] The at least one electrode 148, together with the at least one section 150 of the electrically conductive layer 142 of the sample 102, forms the at least one capacitor 152 with a pre-determined capacitance C. The capacitance C is determined such that a charge Q occurring on the sample surface 118 can be stored in the capacitor 152 by the creation of an electric field E between the electrodes. Fig. 4).

[0133] In particular, the at least one electrode 148 and the at least one section 150 of the electrically conductive layer 142 of the sample 102 are arranged parallel to each other and overlapping in an overlap region 158, as shown in Fig. Figure 5 illustrates the overlap area 158, which defines an area A of the capacitor 152.

[0134] It can also be said that a section 160 of the at least one electrode 148 in the overlap region 158 forms a first plate P1 of the capacitor 152. Furthermore, the at least one section 150 of the electrically conductive layer 142 in the overlap region 158 forms a second plate P2 of the capacitor 152. A dielectric 162 is arranged between the plates P1 and P2. In this case, the dielectric 162 has the vacuum that prevails inside the housing. If the sample 102, as shown by way of example in Fig. 2, has a dielectric layer 144 above the electrically conductive layer 142, then the dielectric 162 between the plates P1 and P2 has the dielectric layer 144 in addition to the vacuum. Since the dielectric layer 144 is usually very thin (e.g. a few nanometers), it can generally be neglected when calculating the capacitance C of the capacitor 152.

[0135] The capacitance C is determined such that a charge Q occurring on the sample surface 118 can be stored in the capacitor 152 by the creation of an electric field E between the Fig. 4).

[0136] To determine the required capacitance C of capacitor 152, so that the amount of charge Q occurring on the sample surface 118 can be stored in capacitor 152, the amount of charge Q is first determined. For this purpose, a current flow I ( Fig. 4) on the sample surface 118 and a duration of this current flow I, for example, based on the following equations.

[0137] As is known, current I equals charge dQ per time dI, as formulated in equation 3. I=dQdt

[0138] For a constant current over time, equation 3 can be reformulated as follows. I=QΔt Q=I⋅Δt

[0139] Equation 5 can be used to calculate the charge accumulation Q from the pre-determined particle beam flux I and the pre-determined time duration Δt.

[0140] As an example only, a maximum value of 50 pA can be assumed for the current I of the particle beam. With a time duration Δt (e.g., processing time) of one hour (3600 seconds), this results in a charge Q on the surface of the sample of 180 nC. Q=I⋅Δt=50 pA⋅3600 s=180 nC In particular, secondary electrons 126 are released from the sample material by the incident primary beam 116, so that the sample surface 118 becomes positively charged ( Fig. 3) Through capacitive coupling using the at least one electrode 148, the positive charges Q are directed towards the capacitor 152 ( Fig. 4) moves (current I). A potential difference ΔU and thus an electric field E then builds up between the plates P1, P2 of the capacitor. This allows the charge Q on the sample surface 118 to be stored in the capacitor 152.

[0141] This means that the charge Q is removed from a processing area 164 of the sample 102 by the capacitor 152 and stored in a capacitor area 166 of the sample 102. In particular, there is no electrically conductive connection between the sample 102 and the at least one electrode 148. Furthermore, the charge Q is not completely removed from the sample 102. Rather, the charge Q is merely displaced on the sample 102 (from the processing area 164 to the capacitor area 166) so that it does not affect, or hardly affects, the primary beam 116 and the secondary beams 126, 146.

[0142] For example, to store a charge of 180 nC, as estimated for the example above, in capacitor 152, the pre-determined electrical potential U M which takes into account at least one electrode 154 and the capacitor area A and the capacitor spacing d or adjusts accordingly.

[0143] For example, a maximum potential difference ΔU between the plates P1, P2 is chosen such that it is small compared to an accelerating voltage U. H The particle beam delivery unit 114 is shown. An accelerating voltage U is shown only as an example. H The particle beam delivery unit 114, for example, has a potential difference of 300 V (i.e., the energy of the electrons in the primary beam 116 is, for example, 300 eV). Furthermore, and only as an example, a maximum potential difference ΔU between the plates P1 and P2 of 1 V is chosen, which is considered small compared to an accelerating voltage U. Hcan be considered to be 300 V.

[0144] The pre-determined capacitance C of the capacitor is calculated, for example, using the following equation: C=ε0εRAd

[0145] Here, ε0 denotes the electric constant of free space (ε0 = 8.854 e -12 As / Vm), ε R the relative permittivity of the dielectric 162 (for vacuum as dielectric ε R = 1), A the pre-determined area of ​​the capacitor 152 and d the distance between the plates P1, P2 of the capacitor (e.g. the distance d between the at least one electrode 148 and the at least one section 150 of the electrically conductive layer 142).

[0146] In other words, the device 100 with the at least one electrode 148 can be designed and / or adjusted such that the area A and the distance d are selected so that the resulting capacitance of the capacitor C is sufficient to store the pre-determined amount of charge Q (e.g., 180 nC in the example above). In the cross-sectional view of Fig. In section 3, only one side a1 of area A is visible. Area A is, for example, a rectangular area A (e.g., Fig. 10), which are obtained by multiplying the side lengths a1 and a2 of the rectangle. For example, side length a1 is 0.02 m and side length a2 is 0.15 m. This results in an example area of ​​0.003 m². 2 Other values ​​can also be used for a1, a2 and therefore A.

[0147] In the Fig. Figures 1 and 3 to 5 show a potential source 154 which has a ground connection to which at least one electrode 148 is connected to a ground potential U1 = U M to maintain. However, the potential source 254 can also be configured to provide a positive and / or negative potential U2 that is not equal to zero, as in Fig. 6 shown.

[0148] In Fig. Figure 6 shows sample 102 and the at least one electrode 248 (similar to the at least one electrode 148 in the Fig. 1 and 3 to 5) of the device 100, which is arranged at a distance from the sample 102. In the embodiment of Fig. 6 is the at least one potential source 254 set up to provide a positive and / or negative potential U2 not equal to zero.

[0149] This allows for a larger potential difference ΔU2 between at least one electrode 248 (corresponding to plate P1 in Fig. 5) and sample 102 (corresponding to plate P2 in Fig. 5) are generated. Thus, a smaller capacitance C' of capacitor 252 (e.g., a smaller area A and / or a larger distance d) is sufficient to store a certain amount of charge Q. This follows directly from the following equation, which gives the capacitance C (C') of capacitor 252 as a function of the charge Q stored in capacitor 252 and the potential difference U (ΔU2) between the plates P1, P2 of capacitor 252: C=QU

[0150] The equation shows that with a larger potential difference U (ΔU2) between the plates P1, P2 of capacitor 252, a smaller capacitance C (C') of capacitor 252 is sufficient to store a certain amount of charge Q in capacitor 252. If a smaller capacitance C (C') of capacitor 252 is sufficient, then, for example, the area A of capacitor 252 can be made smaller and / or the distance d between the plates 252 can be made larger.

[0151] As an example, the sample 102 can be raised to a positive potential using the potential source 254 and the capacitive coupling to the at least one electrode 248. If the particle beam 116 is a beam of negatively charged particles, e.g., an electron beam, then the positively charged sample 102 can exert a braking effect on the particle beam 116. This can, for example, provide an electric immersion lens. Furthermore, the detection efficiency can also be changed because the braking effect on the primary beam 116 simultaneously has a repulsive effect on the secondary electrons 126. Thus, the secondary electrons 126 then increasingly strike the detector(s) 124 in the particle beam delivery unit 128.

[0152] As in Fig. As shown in Figure 7, the device 100 can optionally include a current measuring unit 370. Furthermore, the potential source 354 is electrically connected to the at least one electrode 348 via the current measuring unit 370 (electrical connection 356). Using the current measuring unit 370, a current flowing between the potential source 354 and the at least one electrode 348 can be measured. This allows the charge accumulation Q on the surface 118 of the sample 102 to be determined.

[0153] The in Fig. The current measuring unit 370 shown in Figure 7 can be used for any electrode and potential source shown herein.

[0154] The electrodes 148, 248, 348 described herein can, for example, be attached to the sample table 110 ( Fig. 1, Fig. 8), at the particle beam delivery unit 128 ( Fig. 9) or attached to another structure (not shown) of the device 100.

[0155] Furthermore, in Fig. Figure 7 shows an example of a potential source 354, which is similar to the potential source 254 in Fig. 6 - is set up to provide a positive and / or negative potential U2 that is not equal to zero. In other examples, the potential source 354 can be in Fig. 7, however, for example - similar to the potential source 154 in the Fig. 1 to 3 - also be a ground connection, which connects at least one electrode 348 to a ground potential U M holds.

[0156] The device 100 can optionally also include a control unit RE ( Fig. 19) for controlling the electric potential U2 of the at least one electrode 248, 348. In Fig. Figure 19 shows a control loop FB, which illustrates a feedback control for controlling the electrical potential U2 for the at least one electrode 248, 348.

[0157] The device 100 includes, for example, a device (e.g., the current measuring unit 370 in Fig. 7 or another device) for recording an instantaneous potential y(t) of sample 102 ( Fig. 19).

[0158] The device 100 also includes the control unit RE ( Fig. 19) The control device RE is configured to determine a deviation e(t) of the measured instantaneous potential y(t) of sample 102 from a setpoint r(t) for the potential of sample 192. Furthermore, the control device RE is configured to determine a manipulated variable u(t) based on the determined deviation e(t) and to control the potential source 254, 354 of the at least one electrode 248, 348 based on the determined manipulated variable u(t).

[0159] In Fig. 19 is designated with the reference symbol RS as a controlled system within the control loop FB. The controlled system RS includes, for example, a sensor (e.g., the current measuring unit 370 in Fig. 7 or another device for detecting the instantaneous potential y(t) of the sample 102), an actuator (e.g. the potential source 254, 354), the sample 102 and the at least one electrode 248, 348.

[0160] Furthermore, in Fig. 19 denoted by the reference symbol d(t) is a disturbance variable (e.g. the particle beam 116 striking the sample 102) which changes a potential of the sample 102.

[0161] With the help of the control device RE or the control loop FB, a potential change of the sample 102 caused by the disturbance variable d(t) can be compensated by controlling the electrode potential of at least one electrode 248, 348.

[0162] Fig. Figure 8 shows an embodiment in which the at least one electrode 448 is attached to the sample stage 410 (sample holder). The at least one electrode 448 is attached to the sample stage 410, for example, by means of at least one electrode holder 472.

[0163] For example, in this case the sample table 110 with the sample 102 and the at least one electrode 448 can be moved together relative to the particle beam delivery unit 114 (using the positioning unit of the sample table device 108, Fig. 1) Moving the sample table 110 with the sample 102 and the at least one electrode 448 can be carried out to analyze and / or process different areas of the sample 102 using the particle beam 116.

[0164] In the example of Fig. 8 The at least one electrode 448 is movably attached to the sample stage 410. The movable attachment can, for example, include a hinge or joint 474 for pivoting (folding) the electrode holder 472 (see arrow K). This allows the at least one electrode 448 to be moved (e.g., pivoted or folded) over the sample 102 after the sample 102 has been placed on the sample stage 110, as seen from the particle beam delivery unit 114.

[0165] Alternatively, sample 102 – although not shown in the figures – can also be placed on sample table 110 by lateral (parallel to the x-direction in Fig. 8) Insertion can be arranged. In addition, at least one electrode 448 can then be inserted from above (in the negative z-direction in Fig. 8) be approximated to sample 102.

[0166] The device 100 can, for example, include one or more actuators (not shown) for moving the at least one electrode 448, e.g. for pivoting (folding) the electrode holder 472 (see arrow K).

[0167] Fig. Figure 9 shows an embodiment in which the at least one electrode 548 is mounted on a housing 528 of the particle beam delivery unit 114 ( Fig. 1) is attached. The at least one electrode 548 is, for example, attached to the housing 528 by means of at least one further electrode holder 572. The shape and design of the housing in Fig. Figure 9 is merely an example. The housing 528, to which the at least one electrode 548 is attached, can also have a shape and / or design like the one shown in Fig. 1. Housings shown 128 may have a different shape and / or design.

[0168] The at least one electrode 548 is attached to the housing 528 of the particle beam delivery unit 114 in such a way that the particle beam 116 can pass unhindered from the particle beam delivery unit 114 to the surface 118 of the sample 102. In particular, the area between an outlet opening 530 of the particle beam delivery unit 114 for the particle beam 116 and the surface 118 of the sample 102 is not covered by the at least one electrode 548.

[0169] By attaching at least one electrode 548 to the housing 128, 528 of the particle beam delivery unit 114 ( Fig. 1) The at least one electrode 548 is, for example, fixed in position relative to the particle beam delivery unit 114. This allows the at least one electrode 548 to be positioned partially over a usable area of ​​the sample 102, as seen from the particle beam delivery unit 114. Furthermore, the at least one electrode 548 can be made larger, providing a larger capacitor area A. This allows for the use of a capacitor with a larger capacitance C.

[0170] Although not shown in the figures, the device 100 can, for example, comprise one or more actuators for moving the at least one electrode 448, 548 ( Fig. 8, Fig. 9) in a vertical direction z, i.e., for adjusting the distance d between the at least one electrode 448, 548 and the sample 102. The one or more actuators for adjusting the distance d between the at least one electrode 448, 548 and the sample 102 can, for example, be mounted on the electrode holder 472 ( Fig. 8) or on the electrode holder 572 ( Fig. 9) be arranged. Additionally or instead, the one or more actuators for adjusting the distance d between the at least one electrode 448, 548 and the sample 102 can, for example, also be arranged on the sample stage 110, 410, so that the sample stage 110, 410 itself is movable in the z-direction. For example, the sample stage 110, 410 (and thus also the sample 102) is first moved in the x, y and / or z direction to position the sample 102 for particle beam-induced processing. In doing so, for example, an initial distance between the at least one electrode 448, 548 and the sample 102 is set. Furthermore, starting from the initial distance, the distance d (e.g. as final distance) between the at least one electrode 448, 548 and the sample 102 is set either by means of one or more actuators on the electrode holder 472, 572 or by (further) movement of the sample table 110, 410 in the z-direction.

[0171] Furthermore, the device 100, although not shown in the figures, can, for example, comprise one or more distance sensors for detecting the distance d between the at least one electrode 448, 548 and the sample 102. The one or more distance sensors can, for example, be mounted on the electrode holder 472 ( Fig. 8) or on the electrode holder 572 ( Fig. 9) be arranged.

[0172] The electrodes 148, 248, 348, 448, 548 described herein can have various geometric shapes, as shown in the Fig. Shown from 10 to 17. In the Fig. 10 to 17 are the respective minimum one electrode (e.g. 148 in Fig. 10) and sample 102 in a top view - from the particle beam delivery unit 114 ( Fig. 1) as seen from - shown. In particular covered by the particle beam delivery unit 114 ( Fig. 1) seen from which at least one electrode partially covers sample 102.

[0173] The at least one electrode 148 in Fig. 10 comprises two rectangular electrodes 148, which are arranged in the edge regions of the sample 102. For example, Fig. 3 and Fig. 4 as a cross-section along line BB in Fig. 10 are viewed. It is noted that the Fig. 3 and Fig. 4, however, also as a cross-section of Fig. 11 or Fig. 14 can be viewed.

[0174] The surface 118 of sample 102, for example, has a usable area N and a non-usable area or boundary region R. The at least one electrode 148 is arranged, for example, above the non-usable area or boundary region R of sample 102, as seen from the particle beam delivery unit 114. Furthermore, the usable area N is not covered by the at least one electrode 148. This arrangement is particularly advantageous for electrodes that are attached to the sample stage 110 ( Fig. 8).

[0175] The at least one electrode 648 in Fig. 11 includes an electrode 648 with a square ring shape.

[0176] The at least one electrode 748 in Fig. 12 comprises an electrode 748 with a rectangular shape, which is arranged in a corner region of the sample 102.

[0177] The at least one electrode 848 in Fig. 13 comprises two electrodes 848, each rectangular in shape, arranged in a corner region of the sample 102. For example, the two electrodes 848 are arranged in diagonally opposite corner regions of the sample 102.

[0178] The at least one electrode 948 in Fig. 14 comprises two electrodes 948, each rectangular in shape, arranged in a side region of the sample 102. For example, the two electrodes 948 are arranged on opposite side regions of the sample 102. In contrast to Fig. However, the electrodes 948 do not extend over the entire side length of the sample 102.

[0179] The at least one electrode 1048 in Fig. Figure 15 comprises an electrode 1048 with a circular ring shape. This arrangement is particularly well suited for an electrode that is attached to the housing 128, 528 of the particle beam delivery unit 114. The ring shape features, in particular, a cutout D (opening D) through which the particle beam 116 can move unhindered. The electrode 1048 also has a rotationally symmetric shape with respect to an undisplaced beam direction of the particle beam 116.

[0180] The at least one electrode 1148 in Fig. 16 comprises an electrode 1148 with a circular ring shape with a radially cut-out ring segment F.

[0181] The at least one electrode 1248 in Fig. Electrode 17 comprises two electrodes 1248, which are formed by a circular ring shape with two opposing radially cut-out ring segments F'. Electrode 1248 also has a rotationally symmetrical shape with respect to an undisplaced beam direction of the particle beam 116.

[0182] In Fig. Figure 18 illustrates a method for analyzing and / or processing a sample 102 with a particle beam 116 using a device 100 as described above.

[0183] In a first step S1 of the process, a particle beam 116 is provided on a surface 118 of the sample 102, whereby a charge accumulation Q occurs on the surface 118 of the sample 102.

[0184] In a second step S2 of the process, at least one electrode 148 is positioned at a distance from the surface 118 of the sample 102 and / or the at least one electrode 148 is set to a pre-determined electrical potential U1, U2. The at least one electrode 148, together with at least one section 150 of an electrically conductive layer 142 of the sample 102, forms at least one capacitor 152 with a pre-determined capacitance C. Furthermore, the pre-determined capacitance C is determined based on the pre-determined electrical potential U1, U2 of the at least one electrode 148 and a pre-determined charge accumulation Q on the surface 118 of the sample 102 due to the provided particle beam 116.

[0185] In a third step S3 of the process, charges on the surface 118 of the sample 102 are stored in the at least one capacitor 152.

[0186] Although the present invention has been described using exemplary embodiments, it can be modified in many ways. REFERENCE MARK LIST 100 Device 102 Sample 104 cases 106 Pump 108 Sample table setup 110 Sample table 112 Holding device 114 Particle beam delivery unit 116 particle beam 118 surface 120 electron column 122 Electron source 124 Detector 126 Secondary electron 128 cases 130 Opening 132 Underside 134 Gas supply unit 136 Gas pipeline 138 Control unit 140 substrate 142 electrically conductive layer 144 dielectric layer 146 Trajectory 148 electrode Section 150 152 Capacitor 154 Potential source 156 connection 158 Overlap area Section 160 162 Dielectric 164 processing area 166 Capacitor area 200 arrangement 248 electrode 252 Capacitor 254 Potential source 256 connection 348 Electrode 354 Potential source 356 connection 370 Current measuring unit 410 Sample table (sample holder) 448 Electrode 454 Potential source 472 Electrode holders 474 Joint 528 cases 530 Opening 548 electrode 572 Electrode holders 648 electrode 748 Electrode 848 electrode 948 electrode 1048 electrode 1148 Electrode 1248 electrode Area a1 length a2 length C, C' capacity d distance d(t) disturbance variable D neckline ΔU1 Potential difference ΔU2 potential difference e(t) deviation E electric field F, F' section FB control loop G level I Electricity K direction N area P1 plate P2 plate Q Charge r(t) setpoint R area RE control device RS control loop S1-S3 process steps u(t) Control variable U Potential U1 Potential U2 Potential U M potential x direction y(t) actual value y direction z direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 1 587 128 B1

[0010]

Claims

[1] Device (100) for analyzing and / or processing a sample (102) with a particle beam (116), wherein the sample (102) has an electrically conductive layer (142), comprising: a particle beam delivery unit (114) for delivering the particle beam (116) onto a surface (118) of the sample (102), at least one electrode (148) which is arranged to be spaced apart from the surface (118) of the sample (102) and together with at least one section (150) of the electrically conductive layer (142) of the sample (102) to form at least one capacitor (152) with a pre-determined capacitance (C), and at least one potential source (154, 254) which is electrically connected to the at least one electrode (148) in order to set the at least one electrode (148) to a pre-determined electrical potential (U1, U2), wherein the pre-determined capacitance (C) is determined based on the pre-determined electrical potential (U1, U2) of the at least one electrode (148) and a pre-determined charge accumulation (Q) on the surface (118) of the sample (102) due to the provided particle beam (116). [2] Device according to claim 1, wherein the at least one electrode (148) is arranged to be positioned at a pre-determined distance (d) to the surface (118) of the sample (102) and / or to the electrically conductive layer (142) of the sample (102), the pre-determined distance (d) defines a distance of the at least one capacitor (152), the at least one electrode (148) and the electrically conductive layer (142) of the sample (102) are arranged parallel to each other and overlapping in an overlap area (158), the overlap area (158) defines a pre-determined area (A) of the at least one capacitor (152), and the pre-determined distance (d) and the pre-determined area (A) of the at least one capacitor (152) define the pre-determined capacitance (C) of the at least one capacitor (152). [3] Device according to claim 1 or 2, wherein the at least one potential source (154) is configured to provide a ground potential (U M ) to provide, and the pre-determined capacity (C) based on the mass potential (U) M ) is determined as the pre-determined electrical potential (U1). [4] Device according to claim 1 or 2, wherein the at least one potential source (254) is configured to provide a positive and / or negative potential (U2), and the pre-determined capacitance (C) is determined based on the corresponding provided positive or negative potential (U2) as a pre-determined electrical potential. [5] Device according to one of claims 1 to 4, comprising a sample holder (110, 410) for holding the sample (102), wherein which at least one electrode (148, 448) is attached to the sample holder (110, 410), and / or the sample holder (110, 410) and the at least one electrode (148, 448) are designed to be moved together relative to the particle beam delivery unit (114) for the purpose of analyzing and / or processing the sample (102). [6] Device according to claim 5, wherein the at least one electrode (448) is movably attached to the sample holder (410) so that the at least one electrode (448) is at least partially movable over the sample (102) as seen from the particle beam delivery unit (114) after the sample (102) has been arranged on the sample holder (410). [7] Device according to claim 5 or 6, wherein the surface (118) of the sample (102) has a usable area (N) and a non-usable area (R), the at least one electrode (148) being arranged to be at least partially positioned over the non-usable area (R) of the sample (102) as seen from the particle beam delivery unit (114), such that an area over the usable area (N) is free of the at least one electrode (148). [8] Device according to any one of claims 1 to 4, wherein the particle beam delivery unit (114) has a housing (528), and at least one electrode (548) is attached to the housing (528), and / or the at least one electrode (548) is arranged in a fixed position relative to the particle beam delivery unit (114). [9] Device according to any one of claims 1 to 8, wherein the at least one electrode (148) has a ring shape (1048) as seen from the particle beam delivery unit (114), a circular ring shape (1048), a ring shape (1148) with at least one cutout (F, F'), a rotationally symmetric shape (1048, 1248) with respect to an undisplaced beam direction of the particle beam (116), a rectangular shape (148, 748, 848, 948), and / or an angular ring shape (648). [10] Device according to any one of claims 1 to 9, comprising a current measuring unit (370), wherein the potential source (354) is electrically connected to the at least one electrode (348) via the current measuring unit (370) in order to measure a current flowing between the potential source (354) and the at least one electrode (348). [11] Device according to one of claims 1 to 10, wherein the particle beam delivery unit (114) is set up to provide the particle beam (116) with a pre-determined particle beam current (I) for a pre-determined time period (Δt), and the determined charge accumulation (Q) is determined based on the pre-determined particle beam current (I) and the pre-determined time period (Δt). [12] Device according to any one of claims 1 to 11, wherein the pre-determined capacitance (C) is determined such that a potential difference (ΔU1) between the at least one electrode (148) and the at least one section (150) of the electrically conductive layer (142) of the sample (102) is a factor of 10 smaller, a factor of 100 smaller, a factor of 200 smaller, a factor of 300 smaller, a factor of 500 smaller and / or a factor of 1000 smaller than an accelerating voltage (U) H ) the particle beam delivery unit (114). [13] Arrangement (200) comprising a device (100) according to any one of claims 1 to 12 and a sample (102). [14] Method for analyzing and / or processing a sample (102) with a particle beam (116) using a device (100) according to any one of claims 1 to 12, wherein the sample (102) has an electrically conductive layer (142), comprising: a) Providing (S1) the particle beam (116) on a surface (118) of the sample (102), whereby a charge accumulation (Q) occurs on the surface (118) of the sample (102), b) Setting (S2) at least one electrode (148), which is arranged at a distance from the surface (118) of the sample (102), to a pre-determined electrical potential (U1, U2), wherein the at least one electrode (148) together with at least one section (150) of the electrically conductive layer (142) of the sample (102) forms at least one capacitor (152) with pre-determined capacitance (C), and the pre-determined capacitance (C) is determined based on the pre-determined electrical potential (U1, U2) of the at least one electrode (148) and a pre-determined charge accumulation (Q) on the surface (118) of the sample (102) due to the provided particle beam (116), and c) Storing (S3) charges (Q) on the surface (118) of the sample (102) in the at least one capacitor (152). [15] Method according to claim 14, comprising before step b): Determining the charge accumulation (Q) on the surface (118) of the sample (102), Determining a target value for the capacitance of the at least one capacitor (152) based on the determined charge accumulation (Q), and Adjusting the determined capacitance of the at least one capacitor (152) for the pre-determined electrical potential (U1, U2) of the at least one electrode (148) by adjusting a distance (d) and / or an area (A) of the at least one capacitor (152), wherein the distance (d) of the at least one capacitor (152) is a distance of the at least one electrode (148) to the surface (118) of the sample (102) and / or to the electrically conductive layer (142) of the sample (102), and the area (A) of the at least one capacitor (152) is an overlap region (158) in which the at least one electrode (148) and the electrically conductive layer (142) of the sample (102), which are arranged parallel to each other, overlap. [16] Method according to claim 14, comprising before step b): Detecting an instantaneous electrical potential (y) of the sample (102), and Control of the electrical potential (U2) of the at least one electrode (254, 354), wherein a deviation (e) of the detected instantaneous electrical potential (y) of the sample (102) from a setpoint (r) of the electrical potential of the sample (102) is determined, a manipulated variable (u) is determined based on the determined deviation (e), and the potential source (254, 354) of the at least one electrode (248, 348) is controlled based on the determined manipulated variable (u).

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