Devices and methods for imaging and spectroscopically analysing a sample that interacts with microwave radiation

Abstract

A device (10a) for imaging a sample (12) including a material that interacts with microwave radiation is provided The device (10a) comprises a sample holder (16) for supporting the sample (12) in a sample area, a quantum sensor device (18) configured to be arranged adjacent to the sample area, the quantum sensor device (18) including colour sensors, an excitation light source (30) configured to generate excitation light for energetically exciting the colour sensors, an optical sensor (32) including a plurality of pixels and configured to generate electronic signals indicative of an intensity of the light emitted by the colour sensors, imaging optics (28) for projecting the sensor area onto the optical sensor (32), a microwave source (20) having a microwave antenna for emitting microwave radiation, the microwave source (20) being configured to generate microwave radiation that is characterized by a plurality of parameters, and a controller (24). The sample holder (16) supports the sample (12) such that the sensor area is in the near-field of the microwave radiation interacting with the sample (12), wherein the controller (24) is configured to vary at least one parameter of the microwave radiation at least between a first value and a second value, record – for each pixel – the electronic signals received from the optical sensor (32) for the microwave radiations generated using the first value and the second value, determine – for each pixel – changes in the electronic signals between the microwave radiations generated using the first value and the second value, and generate an image based on the changes for each pixel, the changes for each pixel indicating variations in the interaction of the microwave radiation with the sample (12).

Description

[0001] Devices and methods for imaging and spectroscopically analysing a sample that interacts with microwave radiation

[0002] This invention relates to a device and method for imaging a sample including a material that interacts with microwave radiation. A sample holder for supporting the sample in a sample area and a quantum sensor device are provided. The quantum sensor device is configured to be arranged adjacent to the sample area and includes colour sensors configured to absorb and / or emit light.

[0003] The invention further relates to a spectroscopy device and spectroscopy method for a spectroscopic analysis of a sample including a material that interacts with microwave radiation. A sample holder for supporting the sample in a sample area and a quantum sensor device are provided. The quantum sensor device is configured to be arranged adjacent to the sample area and includes colour sensors configured to absorb and / or emit light.

[0004] The invention also relates to the use of the device and / or the spectroscopy device for analysing an integrated circuit, a printed circuit board, an electronic device and / or a material interface.

[0005] Nitrogen-vacancy (NV) centres in diamond are known to be fluorescent. The intensity of the emitted fluorescent light depends on the spin state of the electrons in the NV centres. The spin state of the NV centres can be influenced by external magnetic fields. This is why the fluorescent light emitted by the NV centres can be used to probe magnetic fields to which the NV centres are exposed. For example, it is known to use NV centres for measuring magnetic fields by monitoring the intensity of the emitted fluorescent light.

[0006] An objective of this invention is to provide a device and method for probing samples for which optical imaging techniques are not feasible because the zone of interest is within the sample and, therefore, cannot be optically imaged.

[0007] This objective is solved by the subject matter of the independent claims. The dependant claims describe optional embodiments of the invention.

[0008] At its most general, the invention refers to optically exciting the colour sensors and measuring the fluorescent light emitted by the colour sensors. For imaging and / or spectroscopically analysing a sample, the sample is subjected to microwave radiation having a parameter which changes the fluorescence of the colour sensors. At the same time, the microwave radiation interacts with the sample, for example is reflected by the sample and / or is absorbed by the sample. The microwave radiation interacting with the sample influences the colour sensors and, therefore, the intensity of the emited fluorescent light. Thus, the intensity of the emited fluorescent light is an indicator of the interaction microwave radiation with the sample. Changes in the intensity of the detected fluorescent light can be used for imaging and / or spectroscopically analysing the sample. As the microwave radiation penetrates the sample, material properties inside the sample can be visualised and / or characterised.

[0009] In a first aspect, a device for imaging a sample including a material that interacts with microwave radiation is provided. The device comprises a sample holder for supporting the sample in a sample area, a quantum sensor device, an excitation light source, an optical sensor, imaging optics, a microwave source, and a controller. The quantum sensor device is configured to be arranged adjacent to the sample area, wherein optionally the quantum sensor device includes colour sensors configured to absorb and / or emit light depending on a parameter of the microwave radiation interacting with the colour sensors. The colour sensors are arranged in a sensor area. The excitation light source is configured to generate excitation light configured to be directed to the sensor area for energetically exciting the colour sensors. The optical sensor includes a plurality of pixels and is configured to generate electronic signals indicative of an intensity of the light emited by the colour sensors. The imaging optics are configured to project the sensor area onto the optical sensor. The microwave source has a microwave antenna for emiting microwave radiation, wherein optionally the microwave source is configured to generate microwave radiation that is characterized by a plurality of parameters. The controller is in data-communication with the microwave source and the optical sensor. The sample holder is configured to support the sample such that the sensor area is in the nearfield of the micro wave radiation interacting with the sample. Optionally, the controller is configured to (i) vary at least one parameter of the microwave radiation at least between a first value and a second value, (ii) record - for each pixel - the electronic signals received from the optical sensor for the microwave radiations generated using the first value and the second value, (iii) determine - for each pixel - changes in the electronic signals between the microwave radiations generated using the first value and the second value, and / or (iv) generate an image based on the changes for each pixel, the changes for each pixel indicating (local) variations in the interaction of the microwave radiation with the sample or sample area.

[0010] In a second aspect, a spectroscopy device for a spectroscopic analysis of a sample including a material that interacts with microwave radiation is provided. The spectroscopy device comprises a sample holder for supporting the sample in a sample area, a quantum sensor device, an excitation light source, an optical sensor, imaging optics, a microwave source, a magnetic source, and / or a controller. The quantum sensor device is configured to be arranged adjacent to the sample area, wherein optionally the quantum sensor device includes colour sensors configured to absorb and / or emit light depending on a parameter of the micro wave radiation interacting with the colour sensors. The colour sensors are arranged in a sensor area. The excitation light source is configured to generate excitation light configured to be directed to the sensor area for energetically exciting the colour sensors. The optical sensor includes a plurality of pixels and is configured to generate electronic signals indicative of an intensity of the light emitted by the colour sensors. The imaging optics are configured to project the sensor area onto the optical sensor. The microwave source has a microwave antenna for emitting microwave radiation. The magnetic source is configured to generate a constant magnetic field through the sensor area, wherein optionally the magnetic source is configured to vary a strength of the magnetic field and / or an orientation of the magnetic field. The controller is in data-communication with the micro wave source, the optical sensor, and / or the magnetic source. The sample holder is configured to support the sample such that the sensor area is in the near-field of the microwave radiation interacting with the sample. Optionally, the controller is configured to (i) vary the magnetic field between a first configuration and a second configuration that differs from the first configuration by the strength and / or orientation of the magnetic field, (ii) record - for each pixel - the electronic signals received from the optical sensor for the magnetic fields generated using the first configuration and the second configuration, (iii) determine - for each pixel - changes in the electronic signals between the magnetic fields generated using the first configuration and the second configuration, and / or (iv) generate the spectroscopic analysis based on the changes for one or more of the pixels, the changes for the one or more pixels indicating (local) variations in the interaction of the microwave radiation with the sample area which are caused by the magnetic field having the first configuration or the second configuration.

[0011] In a third aspect, a method for imaging a sample including a material that interacts with microwave radiation is provided. The method includes the steps of a) placing the integrated circuit adjacent to a sensor area, the sensor area including colour sensors configured to absorb and / or emit light depending on a parameter of the microwave radiation interacting with the colour sensors, b) exciting the colour sensors by irradiating light onto the sensor area and projecting the sensor area onto an optical sensor having a plurality of pixels, c) emitting microwave radiation from a microwave antenna towards the integrated circuit such that the integrated circuit is in the near-field of the microwave radiation interacting with the integrated circuit, the microwave radiation having a parameter of a first value, d) recording - for each pixel - electronic signals indicative of an intensity of the light emitted by the colour sensors, e) repeating steps b) to d) with microwave radiation having the parameter of a second value, f) determining - for each pixel - changes in the electronic signals between the microwave radiations generated using the first value and the second value, and g) generating an image based on the changes for each pixel, the changes for each pixel indicating local variations in the interaction of the microwave radiation with the sample area. Steps b) to d) can be simultaneously executed. It is also possible that steps b) to d) are executed one after the other and / or the order of steps b) and c) can be changed. Further, there may be further optional steps between the steps outlined above.

[0012] In a fourth aspect, a method for determining a quality parameter in an integrated circuit, a printed circuit board, and / or an electronic device is provided. The method includes the steps a) to g) of the method of the third aspect and the additional step of h) determining the quality parameter of the integrated circuit, the printed circuit board, and / or the electronic device using the image generated in step g).

[0013] In a fifth aspect, a method for a spectroscopic analysis of a sample including a material that interacts with microwave radiation is provided. The method includes the steps of I) placing the integrated circuit adjacent to a sensor area, the sensor area including colour sensors configured to absorb and / or emit light depending on a parameter of the microwave radiation interacting with the colour sensors, II) exciting the colour sensors by irradiating light onto the sensor area and projecting the sensor area onto an optical sensor having a plurality of pixels, III) emitting microwave radiation from a microwave antenna towards the integrated circuit such that the integrated circuit is in the near-field of the microwave radiation interacting with the integrated circuit, IV) generating a constant magnetic field through the sensor area, the magnetic field having a first configuration, IV) recording - for each pixel - the electronic signals received from the optical sensor for the magnetic fields generated using the first configuration and the second configuration, V) repeating steps II to IV) with a magnetic field having a second configuration, VI) determining - for each pixel - changes in the electronic signals between the magnetic fields generated using the first configuration and the second configuration, and / or VII) generating the spectroscopic analysis based on the changes for one or more of the pixels, the changes for the one or more pixels indicating (local) variations in the interaction of the microwave radiation with the sample area which are caused by the magnetic field having the first configuration or the second configuration.

[0014] Steps II) to IV) can be simultaneously executed. It is also possible that steps II) to IV) are executed one after the other and / or the order of steps II) to IV) can be changed. Further, there may be further optional steps between the steps outlined above.

[0015] In a sixth aspect, a further method for determining a quality parameter in an integrated circuit, a printed circuit board, and / or an electronic device is provided. The method includes the steps I) to VII) of the method of the fifth aspect and the additional step of VIII) determining the quality parameter of the integrated circuit, the printed circuit board, and / or the electronic device using the spectroscopic analysis generated in step VII). In a seventh aspect, the use of the device according to first aspect or spectroscopy device according to second aspect for analysing an integrated circuit, printed circuit board, electronic device or material interface is provided.

[0016] The invention may facilitate probing the spatial distribution of different materials within a sample. This may include imaging the spatial distribution of different materials within the sample and / or spectroscopically analysing the materials within the sample. With regard to imaging, the microwave radiation reflected and / or absorbed by material interfaces within the sample may be used for imaging the sample. For example, the material properties at an interface affect the reflection characteristics. As an example, the material properties at the interface (e.g. the difference in the dielectric constant of the two materials at the interface) impact the intensity and / or polarization of (reflected) microwave radiation. The properties of the reflected microwave radiation (as an example of microwave radiation interacting with the sample materials) are recorded using the colour sensors.

[0017] The invention provides for non-destructively probing the sample, for example the presence (or absence) of, e.g., metallic structures in optically non-transmissible material (such as deep metallization layers in semiconductor circuitry). Thus, the invention allows to probe samples that cannot be analysed using optical imaging techniques. Further, non-ionising radiation is used reducing the risk of the destruction of the sample as present with X-ray imaging techniques.

[0018] The invention further allows to project the sensor area onto the optical sensor. The sensor area may cover the entire sample or a substantial portion thereof. In this way, sample probing is a fast process, for example compared to known scanning techniques. This may allow to probe the sample in-line and / or a high throughput in fingerprinting samples. Optionally, the invention allows widefield imaging of the sensor area.

[0019] The sample may include any material that interacts with microwave radiation. The term “interacting” relates to changes in the intensity / amplitude (e.g. caused by reflection and / or absorption of the microwave radiation), changes in the polarisation, changes in the phase, and / or changes in the direction (e.g. refraction) of the microwave radiation. In other words, the sample, e.g. the interaction of the sample with the incident microwave radiation, changes a parameter of the incident microwave radiation. The parameter of the microwave radiation may refer to the frequency, the phase, the intensity / amplitude, the polarisation (e.g. clockwise or anti -clockwise) and / or the direction of travel of the microwave radiation. Thus, after impinging on the sample, at least one parameter of the microwave radiation is changed due to the interaction with the sample. For example, the microwave radiation impinges on an interface between a metallic layer and the electric material within the sample. At this interface, the microwave radiation is reflected which is an example of the interaction of the micro wave radiation with the sample.

[0020] The sample may include one or more materials which each may have different properties of interaction with the microwave radiation, for example an absorption coefficient, a reflection coefficient, and / or a dielectric constant. For example, the sample interacts with the microwave radiation that at least one parameter of the microwave radiation is changed by more than 10%, more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, more than 70%, more than 80%, or more than 90% and / or maximally by 100%.

[0021] The interaction of the sample with the microwave radiation may be sufficiently substantial such that changes in the parameter of the microwave radiation due to the interaction with the sample have a sufficiently significant effect on the fluorescent light emitted by the colour sensor, e.g. the intensity of the fluorescent light emitted by the colour sensors. Stated differently, the interaction of the microwave radiation with the sample is sufficiently high such that it can be recorded using the colour sensors with a sufficient signal -to-noise ratio. Of course, this strongly depends on the parameter of the microwave radiation, the material properties of the sample, and / or the colour sensors used.

[0022] The sample holder may be any device that is configured to removably support the sample and / or to which the sample can be removably attached, e.g. fastening means. Commonly known sample holders may be used. The sample holder defines a sample area in which the sample is located when the sample is probed. The sample area may have a circular, quadratic or rectangular cross-section. The size of the sample area can include a maximal length / diameter of 100 pm, 200 pm, 300 pm, 400 pm, 500 pm, 600 pm, 700 pm, 800 pm, 900 pm or 1000 pm and / or a minimal length / diameter of 10pm. The size of the sample area may be, for example, 1000 pm2, 2000 pm2, 3000 pm2, 4000 pm2, 5000 pm2, 6000 pm2, 7000 pm2, 8000 pm2, 9000 pm2or 10000 pm2.

[0023] Further, the sample holder is configured to support the sample in such a position that the sample is close to or in contact with the sensor area of the quantum sensor device. In this way, the colour sensors of the quantum sensor device can be arranged close to or directly adjacent to the sample. Optionally, the sample holder is configured to support the sample as close as possible to the sensor area.

[0024] The quantum sensor device may be attached to the sample holder. For example, the sample is placed on the quantum sensor device that is in turn supported by the sample holder. The quantum sensor device may be made from an optically transparent material such that the excitation light can reach the colour sensors without or only minimal loss of intensity. The quantum sensor device may include a sample side and an optics side which opposes the sample side. The quantum sensor device and the sample holder are configured to be arranged such that the sample is in contact with or directly adjacent to the sample side of the quantum sensor device.

[0025] The light generated by the excitation light may impinge on the optics side and travel through the quantum sensor device to reach the sensor area. The light emitted by the colour sensors may exit the quantum sensor device at the optics side. It is also possible that the excitation light enters the quantum sensor device at the sample side and exits the quantum sensor device at the optics side. The optics side may face the imaging optics and / or the sample side may face the sample.

[0026] The quantum sensor device may have a cuboid or cylinder shape. For example, the quantum sensor device may have the shape of a plate or disc. In this case, the sample side and / or the optics side may form a flat, non-curved surface. Alternatively, the quantum sensor device may form a lens wherein optionally the sample side is also a flat surface and the optics side is curved and / or shaped to optically refract the impinging and / or exiting light.

[0027] The colour sensors correspond to those elements within the quantum sensor device which are energetically excited by the excitation light and emit fluorescent light. The colour sensors may be solid state quantum sensors which may be defects in the crystallin material of the quantum sensor device. The colour sensor may be provided in the crystallin material by doping the material and / or treating the material (e.g. using a laser). Further, the quantum sensor device may be grown by epitaxy. This process can be controlled in such a way that the colour sensors are provided in the desired concentration and / or location.

[0028] The quantum sensors may be arranged in a predefined volume or layer within the quantum sensor device. For example, the quantum sensors are arranged in a layer at or close to the sample side of the quantum sensor device. The layer in which the colour sensors are arranged form the sensor area. It is possible that the colour sensors are arranged in patterns.

[0029] The sensor area may extend along the entire sample side or may extend over a section of the sample side. The sensor area may cover an area of between 0.01 mm2and 20 mm2, optionally 0.2 mm2to 2mm2, further optionally between 0.5 mm2to 1 mm2. The sensor area may have a thickness between 0.01 pm to 1 nm, optionally between 0.1 pm to 100 pm, further optionally between 1 pm and 50 pm. The thickness and / or the size of the sensor area may depend on the size and / or shape of the quantum sensor device and / or the imaging optics. Optionally, the sensor area may have a longitudinal extension and / or a thickness such that the entire sensor area can be projected onto the optical sensor. For example, the thickness of the sensor area is sufficiently small such that a sharp image of the colour sensors can be projected onto the optical sensor. A sensor area having a large thickness would result in a blurred image of the colour sensors on the optical sensor. Further, if the sample area has a large thickness, the distance between an individual colour sensor and the sample would substantially vary which may introduce undesired differences in the interaction of the interacting microwave radiation with the colour sensors.

[0030] The quantum sensor device may be a diamond with nitrogen-vacancy (NV) centres as colour sensors. Alternatively, the quantum sensor device may be made from silicon carbide (SiC) and the colour sensors correspond to bandgap point defects.

[0031] The quantum sensor device may be permanently or removably attached to the sample holder. Thus, upon attaching a sample to the sample holder, the sample holder may support both the quantum sensor device and the sample. For example, the sample holder is configured such that the sample can be put or he on the sample side of the quantum sensor device.

[0032] The excitation light source may comprise one or more lasers, one or more LEDs (Light Emitting Diodes) and / or one or more light sources with a broadband emission spectrum. The light source may generate light of a wavelength or narrow wavelength range (for example 10 nm, 20 nm, 50 nm or 100 nm). Optionally the wavelength or wavelength range generated by the excitation light source includes one or more wavelengths absorbed by colour sensors (e.g. that excite the colour sensors). The excitation light source may also include a broadband light source which generates light having a wavelengths over a wavelength range, for example a white light source. The wavelength(s) generated by the excitation light source may be chosen and / or selected such that the excitation light is absorbed by the colour sensors for exciting the colour sensors. In other words, the energy of the light generated by the excitation light source may correspond to the energy required for exciting colour sensors, for example for increasing the energy state of an electron of the colour sensor.

[0033] The excitation light source may be configured to continuously emit the excitation light during the entire measurement. This is often called continuous wave (CW) measurement. Alternatively, the excitation light source may be configured to emit pulses of the excitation light. For example, the excitation light source emits a first pulse of the excitation light prior to the emission of the microwave radiation and a second pulse of the excitation light after the emission or during the emission of the microwave radiation. The optical sensor can be triggered in such a way that it only records the fluorescent light during the emission of the second excitation light pulse and / or after the emission of the second excitation light pulse. The wavelength of the excitation light may be 532 nm.

[0034] The excited colour sensor emits fluorescent light because the energy state eventually returns to a lower energy state after being excited by the excitation light. Usually, the energy gap between the excited state and the lower energy state is lower than the energy of the excitation light such that the fluorescent light as a higher wavelength compared to the wavelength of the excitation light. For example, for NV-centres, the excitation light may be green and the fluorescent light may be red.

[0035] The excitation light source, the optical sensor, and the imaging optics may form a wide-field microscope for exciting and / or imaging the colour sensors. The beam path of the wide-field microscope may not have an aperture (also known as a pinhole), which is used to select a layer along the z-axis or optical axis of the optical path, as is common in confocal microscopy. In this way, the setup of the present invention can be simplified and / or the light yield increased.

[0036] The colour sensor may be exclusively located in the sensor area and the remainder of the quantum sensor device may be essentially free of colour sensor. This enables the use of wide-field microscopy because there is no superposition of signals from the sensor area with signals from the remainder of the quantum sensor.

[0037] The magnification of the wide-field microscope can be lx, lOx, 20x, 50x, lOOx, 200x or 400x. The magnification can be adjusted, for example, by the magnification of the imaging optics. The imaging can be adjusted by varying the parameters magnification, number of pixels, and size of the optical sensor.

[0038] The optical sensor may be a device for recording two-dimensional images from light by electrical or electronical means. Semiconductor-based optical sensors that can record light up to the mid-infrared range can be used. Examples of optical sensors in the visible and near infrared range are CCD sensors. The optical sensor can convert an incident light into electrical or electronic signals, with the electrical and electronic signals indicating the intensity of the incident light and / or the wavelength of the incident light, optionally with spatial resolution. For example, the optical sensor has a plurality of pixels, each of which generates electrical or electronic signals. The electrical and electronic signals indicate the intensity of the incident light and / or the wavelength of the incident light. The plurality of electrical and electronic signals generated by the pixels could be converted into a two-dimensional image. However, as outlined in the following, the electronic signals are processed before the image is generated as outlined in the following. The image sensor may have a number of pixels of 50x50 pixels; 250x250 pixels; 1000x1000 pixels; 2000x2000 pixels, 4000x4000 pixels or 8192x8192 pixels. The image sensor may be non-square and have one of the above values for the number of pixels along one direction. The size of the image sensor is optionally 1x1 pm2, 2.5x2.5 pm2, 5x5 pm2, 10x10 pm2, 25x25 pm2or 50x50 pm2. As mentioned, the image sensor can also be non-square and then have an edge length with the values mentioned.

[0039] The imaging optics may include one or more optical elements that are configured to provide optical paths for the excitation light and / or the fluorescent light emitted by the colour sensors. For example, the one or more optical elements include an objective, lenses, a beam splitter, an optical filter, a mirror, and / or a dichroic mirror.

[0040] An optical path for exciting the colour sensors may start from the excitation light source over a dichroic mirror, through an objective to the colour sensors. An optical path for the fluorescent light may start from the colour sensors through the objective and the dichroic mirror onto the optical sensor. Thus, there might be a common optical path through the objective. The dichroic mirror may be used to couple in the excitation light in the common optical path or couple out the fluorescent light from the common optical path. Those optical setups are known in the prior art.

[0041] The imaging optics project the colour sensors onto the optical sensor. The fluorescent light emitted by a group of colour sensors may therefore be projected onto a single pixel. In other words, the electronic signals generated by each pixel of the colour sensor may correspond to the intensity and / or wavelength of a corresponding group of colour sensors. Stated differently, the imaging optics projects a sub-volume of the sensor area onto a respective pixel. The fluorescent light emitted by the colour sensors in this sub-volume is recorded by the respective pixel.

[0042] The microwave source may include a generator for generating microwave electromagnetic energy and a microwave antenna that is electrically coupled to the generator. The microwave antenna is configured to emit the microwave electromagnetic energy that is generated by the generator. Thus, the microwave radiation is emitted at the microwave antenna. The microwave radiation may have a wavelength between 1 mm to 1 m or a frequency of between 300 GHz - 300 MHz

[0043] The generator of the microwave source may be configured to generate the microwave electromagnetic energy in a wavelength range having an energy range that corresponds to a resonance state of the colour sensors. In other words, the energy of the microwave radiation may be set to such a wavelength that corresponds with an energy gap of the colour sensors. Thus, the microwave radiation can be used to excite the colour sensors and / or depopulate excited energy states of the colour sensors. For example, the microwave radiation may be used to initiate a population transfer from on energy level to another energy level of the colour sensor.

[0044] The microwave antenna may be a monopolar antenna or dipole antenna.. The microwave antenna may include a ring structure, have the shape of a loop, and / or include one or more elongated structures (e.g. a rod) for emitting the microwave radiation. For example, the microwave antenna at least partially extends around the quantum sensor device. The micro wave antenna may be shaped and / or located such that the electric field generated by the microwave radiation is approximately homogeneous over the sensor area and / or the sample area.

[0045] In some examples, the microwave radiation is used to manipulate the colour sensors in such a way that it affects the fluorescence response of the colour sensors upon excitation by the excitation light source. For example, the microwave radiation is provided for increasing the intensity of the fluorescent light emitted by the colour sensors. This may be done by exciting the colour sensors to an energy level at which the colour sensors can absorb the excitation light.

[0046] Alternatively, the microwave radiation is provided for decreasing the intensity of the fluorescent light emitted by the colour sensors. This may be done by depopulating energy states that are excited by the excitation light. Thus, in the absence of the sample and / or the microwave radiation interacting with the sample, the microwave radiation that is emitted by the microwave antenna and directly interacting with the colour sensors (e.g. without previously interacting with the sample) influences the intensity of the fluorescent light emitted by the colour sensors. For example, the microwave radiation may have a frequency that is in resonance with the colour sensors or is off resonance. Thus, the application of the microwave radiation (directly from the antenna) varies the fluorescence response of the colour sensors.

[0047] The microwave radiation interacting with the sample and impinging on the colour sensors may vary the effective microwave radiation interacting with the colour sensors. In other words, the effective microwave radiation interacting with the colour sensors is a superposition of the microwave radiation directly emitted by the micro wave antenna and the micro wave radiation interacting with the sample. Thus, the intensity of the fluorescent light emitted by the colour sensors depends on the interaction of the microwave radiation with the sample. This is expressed by the intensity of the emitted fluorescent light, for example in that the microwave radiation interacting with the sample increases the intensity of the fluorescent light or decreases the intensity of the fluorescent light.

[0048] The presence of the sample (e.g. the microwave radiation interacting with the sample) changes the variation of the fluorescence response of the colour sensors as induced by the microwave radiation. Thus, the invention is based on determining deviations in the fluorescence response that is manipulated using microwave radiation.

[0049] The magnetic source may include a permanent magnet and / or one or more coils that are configured to generate a magnetic field. The magnetic source may also be configured to vary a configuration of the magnetic field. The configuration of the magnetic field may refer to the orientation and / or strength of the magnetic field. The magnetic field of the first configuration may differ in the orientation and / or strength from the magnetic field of the second configuration. For example, the magnetic field of the first configuration may have to same orientation as the magnetic field of the second configuration and differs in the strength of the respective magnetic field. The configuration of the magnetic field (e.g. the strength of the magnetic field) may be tuned such that the gradient of change in the electronic signals (e.g. a change in the absorption and / or emission of the light by the colour sensors) is maximal.

[0050] The magnetic field generated by the magnetic source may be constant for the time over which the electronic signals, the microwave radiation, and / or the excitation light are generated. In other words, the magnetic field generated by the magnetic source may be constant for the time of one measurement. The magnetic field generated by the magnetic source is at least present in the sample area and / or the sensor area. Due to the proximity of the sample area and the sensor area, the magnetic field generated by the magnetic source may also be present in both the sensor area and the sample area. The magnetic field generated by the magnetic source may be configured to be constant and / or homogeneous throughout the sample area and / or the sensor area.

[0051] The controller can be implemented by a computer and / or can implemented the data-processing steps of the methods described herein. The controller can read out the electrical or electronic signals generated by the optical sensor, convert them into a digital image and / or calculate an image of the physical quantity from the digital image and / or the electronic signals. The controller may include a processor and a memory which stores programs, algorithms, and / or software that are executed by the processor.

[0052] The data-communication of the controller with the excitation light source, the optical sensor, the microwave source, and the magnetic source may be provided by a wired connection or by a wireless connection. The controller may receive the electronic signals from the optical sensor and / or can control the excitation light source, the microwave light source, and / or the magnetic source. For example, the controller may control the wavelength and / or the intensity of the excitation light, the parameter of the micro wave radiation, and / or the configuration of the magnetic field. The sample holder supports the sample in such a way that the sensor area, optionally the colour sensors, are in the near-field of the microwave radiation interacting the sample. The colour sensors may be in the far-field or the near-field of the microwave radiation emitted from the microwave antenna.

[0053] In the far-field, the limit of optical resolution, the so-called diffraction limit, is in the order of half the wavelength of the light used to image the sample. Thus, microwave radiation in the far-field would not provide sufficient optical resolution. However, this lower boundary of the optical resolution does not apply in the near-field. Rather, near-field optics is used which considers configurations that depend on the passage of light to, from, through, or near the sample with subwavelength features, and the coupling of that light to the colour sensors located a subwavelength distance from the first. Thus, the distance between the sample and the sensor area depends on the wavelength on the microwave radiation. Optionally, the distance between the sample and the colour sensors is a 1 / 20, 1 / 15, 1 / 10, or 1 / 5 of the wavelength of the microwave radiation.

[0054] Operating in the near-field allows increasing the resolution of the colour sensors with regard to detection of the microwave radiation interacting with the sample. In other words, it is assumed that a colour sensor or a cluster of colour sensors (e.g. the cluster of colour sensors that is projected onto a single pixel) will only be influenced by the microwave radiation that interacts with a portion of the sample that is closest to this colour sensor or cluster of colour sensors. Microwave radiation that interacts with a portion of the sample further away from the colour sensor or cluster of colour sensors may not or only insignificantly influence the response of the colour sensor. In other words, operating in the near-field may allow a spatial resolution of the colour sensors and / or a coupling of a single colour sensor cluster of colour sensors to a corresponding small volume of the sample whereby the coupling is provided by the microwave radiation interacting with the sample and being in the near- field.

[0055] A measurement may refer to recording of the electronic signals for a specific parameter set of the microwave radiation and / or a specific configuration of the magnetic field. Optionally, for generating the image of the sample and / or providing the spectroscopic analysis of the sample, a plurality of measurements is made whereby, for each measurement, a parameter of the parameter set and / or the configuration of the magnetic field is changed. This allows to see changes in the interaction of the microwave radiation with the sample which can be used for generating the image or for providing a spectroscopic analysis.

[0056] The parameter set may refer to all parameters that can be used to characterise the physical properties of the microwave radiation. The parameter set may include the frequency, the intensity, the amplitude, polarisation, and / or the phase of the microwave radiation. The parameter “amplitude” may include parameters for defining amplitude modulation (AM) of the microwave radiation, frequency modulation (FM) of the microwave radiation, and / or a (periodic) switch between amplitude zero and a predetermined value (e.g. microwave radiation on or off).

[0057] Optionally, only a single parameter of the parameter set is changed for each measurement. A change of a parameter may correspond to the change in the value of the respective parameter. For example, a first value of the parameter refers to a first frequency of the microwave radiation and a second value of the parameter refers to a second frequency of the microwave radiation. Of course, the first and second values may refer to a different parameter, for example the intensity of the microwave radiation and / or the phase of the micro wave radiation. A value of the parameter may characterize an amplitude modulation of the micro wave radiation.

[0058] Further, the magnetic field may also be characterised by a set of parameters with which the magnetic field can be described. A set of parameters may be considered a first configuration or a second configuration. In other words, the magnetic field of the first configuration differs at least in one physical property from the magnetic field of the second configuration.

[0059] As described above, for generating the image and / or for providing a spectroscopic analysis, a plurality of measurements are made whereby a single parameter may be varied in various steps (e.g. sweeping the parameter), the type of parameters that is changed varies between measurements, and / or a combination thereof. Increasing the number of measurement can provide a reduction of an error in the generation of the image and / or in the provision of the spectroscopic analysis.

[0060] For each measurement, the electrical signals received from each pixel are recorded. In other words, when measurement is made using the first value of the parameter and / or the magnetic field of the first configuration, the electronic signals of all pixels are recorded. In other words, a preliminary image of the colour sensors is recorded. Subsequently, a further preliminary image of the colour sensor is recorded using the second value of the parameter and / or the magnetic field of the second configuration. Thus, for every value of the parameter of the microwave radiation and / or for every configuration of the magnetic field, such a preliminary image of the colour sensors is recorded. It is to be noted that these preliminary images may not be displayed. Rather, the electronic signals of each measurement and for each pixel is further analysed as described below.

[0061] Subsequently, changes in the electronic signals are determined between the first preliminary image (i.e. the first measurement) and the second preliminary image (i.e. the second measurement). This means that the electronic signals for the first pixel of the first measurement is compared to the electronic signal of the first pixel of the second measurement and a change thereof is determined. This process is repeated for the second pixel to the last pixel. Thus, at the end of this process, changes in electronic signal for each pixel are determined. Thus, it is possible to generate an image based on the changes of the electronic signals in each pixel. This final image may have to same number of pixels as the preliminary images. In other words, the final image is generated by comparing all preliminary images and determining the differences or changes therein.

[0062] The determination of the changes in the electronic signals for each pixel may correspond to recording a difference in the intensity of the electronic signals (corresponding to the intensity of the emitted fluorescent light). Such an approach may be used if only two measurements are made, for example a measurement is made for microwave radiation having a parameter of the first value and for microwave radiation having the parameter of the second value. In this case, the first value may correspond to microwave radiation that is off resonance with the colour sensors (for generating a base value or base level) and the first value may correspond to microwave radiation that is in resonance with the colour sensors. The difference between the electronic signals of the second value and the first value thus may indicate the change in the intensity of the fluorescent light emitted by the colour sensors which is due to the microwave that interacted with the sample.

[0063] If more measurements are made, the determination of the difference in the electronic signals may include a statistical analysis of the plurality of electronic signals for each pixel. For example, the difference may correspond to a statistical deviation. For example, it is possible to determine a base level and (statistically) determine a deviation from this base level. The base level may be considered corresponding to a state where the microwave radiation is not in resonance with the energy levels of the colour sensors. The deviation from the base level may correspond to the determination of a fluorescence response of the colour sensors to the microwave radiation that interacted with the sample.

[0064] It is also possible to record for each pixel a graph, diagram, and / or plot of the electronic signals over the respective measurements (e.g. over the frequency of the microwave radiation). The determination of the changes in the electronic signals may include fitting a curve to the graph, running a statistical analysis of the graph, and / or further analysing the fitted curve, for example determining a minimum or maximum of the fitted curve or a maximal gradient of the fitted curve.

[0065] This analysis may be connected to the value of the parameter of the microwave radiation and / or the configuration of the magnetic field. For example, changes in the minimum or the maximum of the electronic signals (corresponding to the intensity of the fluorescent light) can thereby be attributed to particular interactions of the microwave radiation and / or the magnetic field with the sample. In other words, these changes in the values of the electronic signals correspond to changes in the interaction of the microwave radiation and / or the magnetic field with the sample.

[0066] For the spectroscopic analysis, these changes may be recorded and displayed. Alternatively, the results of the spectroscopic analysis may be compared with data banks to determine the material that is interacting with the microwave radiation.

[0067] The spectroscopic analysis may be made for each pixel such that an image indicating a spectroscopic analysis each pixel can be displayed. Alternatively, the preliminary image of each measurement may provide a mean value which is compared to a mean value of the preliminary image of a further measurement. It is also possible that, for each pixel, the spectroscopic analysis is made and mean value of the final image is generated, i.e. a mean value of the spectroscopic analysis of each pixel. This may help to reduce the error in the spectroscopic analysis.

[0068] With the spectroscopic analysis, the differences in the interaction of the microwave radiation with the colour sensors depend on the configuration of the magnetic field. Thus, it is possible to use a single parameter set of the microwave radiation for the spectroscopic analysis. However, for the spectroscopic analysis, the configuration of the magnetic field is changed. In other words, changes in the interaction of the microwave radiation with the colour sensors depend on the change in the configuration of the magnetic field. Thereby, the changes in the configuration of the magnetic field result in a change in the absorption and / or emission characteristics of the colour sensors. Thus, for a microwave radiation having a fixed parameter set, changing the configuration of the magnetic field results in a variation of the emission and / or absorption characteristics of the colour sensors which can be used to spectroscopically analyse the sample. In other words, the magnetic field is used to change the microwave wavelengths that interact with colour sensors. For example, the magnetic field “selects” a certain orientation of a plurality of orientations that the colour sensors can have. This can be used to change the energy levels of the colour sensors which provide the absorption of light and / or the emission of fluorescent light.

[0069] In an example for demonstrating the working principle of the spectroscopic analysis, the magnetic field passes through the sensor area (e.g. a layer of NV centres) for the NV centres to detect a change in the magnetic field. This applies both to the external "bias" magnetic field (strong magnetic field that can be used to spectrally distinguish the individual NV axes) and to the magnetic fields of the sample (typically small magnetic fields, permanent magnets or B-fields induced by currents).

[0070] With a certain configuration of the magnetic field, spectral statements can be made about the behaviour of the microwave at eight different frequencies (four different spatial orientations of the NV centres each times two by Zeeman splitting: 4*2=8). The spectral position (frequency) of these eight transitions can be changed by the strength and orientation of the external magnetic field (e.g. by changing the configuration of the magnetic field).

[0071] The interaction of the magnetic field and the sample may therefore be not decisive for spectroscopy. The external magnetic field is used to change the “sensitive” microwave frequencies. In the example described above, only the microwave interacts with the sample.

[0072] In an example of a spectroscopic measurement, ten measurements are made, each with 10 different configurations (strength + orientation) of the magnetic field, allowing 80 frequencies (10 measurements * 8 transitions = 80). In this example, these 80 frequencies can be in the range 2.5 to 3 GHz. Each measurement is analysed by determining the "integral" of the profile (as outlined further below). High integral values indicate increased microwave power, low values indicate more absorption, for example. The final result is a microwave frequency-dependent behaviour (spectroscopy).

[0073] For imaging the sample, a magnetic field may not be present or may not be changed for the measurement. In other words, the configuration of the magnetic field may be the same for each measurement made for imaging a sample. When imaging the sample, the value of one or parameters is changed. Thus, the final image may show changes in the interaction of the microwave radiation depending on the value of the parameter.

[0074] The final image and / or the spectroscopic analysis may be used to determine a quality parameter of the sample. The quality parameter may refer to a measure to quantify the quality of the sample. As described above, the sample may include an integrated circuit, a printed circuit board, an electronic device, and / or a material interface. The quality parameter may be used to determine components of the sample, such as a material interfaces within the sample for example a metallic conductor within a dielectric material.

[0075] The quality parameter may refer to a width, length, and / or curvature of the feature to be identified, for example a metallic conductor within a dielectric material. The quality parameter may also refer to a ratio of the width to length and / or the length to the curvature. The sample may be classified as faulty if the quality parameter deviates from an expected quality parameter by more than 10%, more than 20%, more than 30%, more than 50%, more than 60%, more than 70% or more than 80%, and / or less than 100%. Such a deviation may indicate an interrupted conductor and / or an undesired electrical connection between to conductor (e.g. a shortcut). The controller may be configured to automatically attribute a quality parameter to the image and / or the spectroscopic analysis. It is also possible that a user analysing the image and / or spectroscopic analysis attributes a quality parameter and compares the attributed quality parameter with the expected value for determining whether the sample includes a fault or not.

[0076] In an optional embodiment of the devices and / or methods described herein, the device further comprises a magnetic source for generating a constant magnetic field through the sensor area. The magnetic source is configured to vary a strength of the magnetic field and / or an orientation of the magnetic field. Optionally the controller is in data-communication with the magnetic source and / or configured to (i) vary the magnetic field between a first configuration and a second configuration that differs from the first configuration by the strength and / or orientation of the magnetic field, (ii) record - for each pixel - the electronic signals received from the optical sensor for the microwave radiations generated using the first value and the second value and the magnetic fields generated using the first configuration and the second configuration, (iii) determine - for each pixel - changes in the electronic signals between the microwave radiations generated using the first value and the second value and magnetic fields generated using the first configuration and the second configuration, and (iv) generate the image based on the changes for each pixel, the changes for each pixel indicating local variations in the interaction of the microwave radiation with the sample area which are caused by the magnetic field having the first configuration or the second configuration.

[0077] The above-described considerations regarding the magnetic source and their application equally apply for this optional embodiment. With this optional embodiment, the device for imaging can be also used for spectroscopically analysing the sample. Optionally, the magnetic source is not configured to vary the strength and / or orientation of the magnetic field. In this case, the constant magnetic field may be provided for inducing energy level splits with the colour sensors.

[0078] Optionally, the strength and / or the orientation of the magnetic field can be swept, i.e. the strength and / or the orientation of the magnetic field is stepwise changed, for example between the first configuration and the second configuration. In an example, the strength of the magnetic field is varied between 0 mT and 10 mT, optionally between 1 mT and 8 mT, further optionally between 2 mT and 3.54 mT or between 2.5 mT and 3.5 mT.

[0079] In an additional or alternative example, the orientation of the magnetic field is varied between 0° and 180°. The step size (e.g. the change in the strength and / orientation of the magnetic field for the current measurement compared to the previous measurement) can be selected depending on the range of the sweep and / or the number of measurements to be made. The presence of the magnetic field may split the energy levels of the colour sensors which is called Zeeman-Splitting. Further, the presence of the magnetic field may enhance and / or suppress the response of the colour sensors depending on the orientation of the magnetic field with regard to the orbitals of the colour sensors. It may be possible to record for each orientation of the orbitals a resonance of the colour sensors with the micro wave radiation. By varying the orientation of the magnetic field, this resonance can be suppressed or enhanced. Further, each of these resonances may be recorded and used for determining the changes in the electronic signals recorded for each pixel and each measurement. For example, a triplet of resonance is used which corresponds to transitions of the 0 -» ±1 states.

[0080] In an optional embodiment of the spectroscopy device, the microwave source is configured to generate microwave radiation that is characterized by a plurality of parameters. Optionally, the controller is in data-communication with the microwave source and / or configured to (i) vary at least one parameter of the microwave radiation at least between a first value and a second value, (ii) record

[0081] - for each pixel - the electronic signals received from the optical sensor for the microwave radiations generated using the first value and the second value and magnetic field generated using the first configuration and the second configuration, (iii) determine - for each pixel - changes in the electronic signals between the microwave radiations generated using the first value and the second value and magnetic field generated using the first configuration and the second configuration, and (iv) generate the spectroscopic analysis based on the changes for each pixel, the changes for each pixel indicating local variations in the interaction of the micro wave radiation with the sample area which are caused by the magnetic field having the first configuration or the second configuration.

[0082] The above-described considerations regarding the microwave source and their application equally apply for this optional embodiment. With this optional embodiment, the spectroscopy device can be also used for imaging the sample.

[0083] In an optional embodiment of the devices and / or methods described herein, at least one parameter is a frequency of the microwave radiation. Optionally, the controller is configured to (i) sweep the frequency of the microwave radiation at least between the first value and the second value, (ii) record

[0084] - for each pixel and for each frequency between the first value and the second value - the electronic signals received from the optical sensor for the microwave radiation, and (iii) generate - for each pixel - a graph based on the intensity of the received light depending on the frequency of the microwave radiation and calculate an area of a section of the graph, and / or (iv) generate the image based on the changes in the area of the section of the graph. With this embodiment, many measurements are made and not two measurements as exemplified above. Optionally, the value of the parameter is swept between a lower limit which may correspond to the first value and upper limit which may correspond to the second value. The difference in the frequency between two measurements may be between 100 Hz and 5 MHz or 100 Hz, 500 Hz, 1 kHz, 5 kHz, 10 kHz, 20 kHz, 50 kHz, 10 kHz, 50 kHz, 100 kHz, 200 kHz, 400 kHz, 500 kHz, 1 MHz, 2 MHz, 3 MHz, 4 MHz, or 5 MHz. The frequency range between which the microwave radiation is swept may be between 2 GHz and 4 GHz, between 2.5 GHz and 3.5 GHz or between 2.8 GHz and 3.2 GHz.

[0085] Due to the sweep of the frequency of the microwave radiation, it is possible to generate a graph of electronic signals for each pixel. The value of the electronic signal may be recorded on the y-axis and the number of the measurement or the frequency of the microwave radiation is recorded on the x-axis. For determining the changes in the electronic signals, a curve may be fitted to this graph. The determination of the changes in the electronic signals may be based on fitted curve or on the graph itself. For fitting a curve to the graph, assumption of the shape and / or the type of curve can be made which are based in the physical model of the interaction of the microwave radiation with the colour sensors. For example, a dips or a local minima in the intensity of the emitted fluorescent light can be expected at the resonance frequencies of the colour sensors. Thus, the curve may model this dip in the intensity.

[0086] The graph and / or the fitted curve may include one or more local extrema in the intensity whereby each local extremum in the intensity corresponds to different resonance frequency of the colour sensors. When determining changes in the intensity of the received light and / or the value of the electronic signals, an area for each local extremum can be calculated. Alternatively, the area of all local extremum can be calculated or only selected dips and peaks are used for calculating the area. The calculation of the area of the local extremum or the local extrema may include determining a base line of the graph which may relate to the intensity of the fluorescent light away from the resonance of the colour sensors with micro wave radiation.

[0087] Using the area of the local extremum may have various advantages, for example any base level can be excluded from the calculations and / or errors in individual measurements can be either excluded or smoothed by fitting a curve to the graph.

[0088] The area or the section of the graph may correspond to an area of interest (e.g. the area of the local extremum) There are several options of determining the area of the section of a graph which is a measure for estimating the absorption strength of the colour sensors and / or the intensity of the light emitted by the colour sensors. A first option is to integrate the fitted curve under the continuum yielding the so-called equivalent width, EW:

[0089] Here, Sv / Sv, ref is the contrast of the ESR spectrum at frequency v. Vo and Vi are the lower and upper frequency bounds, respectively, of the region of interest (which may correspond to one triplet). The equivalent width is the width (in frequency units) of a rectangle of height 1 and the area the spectrum encloses relative to the continuum. This calculation may be individually done for each of the triplets (in case a magnetic field is present). Using this measure provides a property that is polarizationsensitive.

[0090] An alternative to the EW is the first moment of the distribution (weighted mean frequency; in frequency units) which can be calculated as follows:

[0091] Compared to the equivalent width (EW), the first moment shows a very strong gradient, which may be attributed to the spatial gradient of the bias magnetic field (large-scale shifting of the entire triplet in frequency space).

[0092] In an optional embodiment of the devices and / or methods described herein, the microwave antenna and the optical sensor are arranged on the same side of the sample area so that the colour sensors are subjected to microwave radiation reflected from the sample area. Optionally, the microwave antenna is located on a side of the quantum sensor device that faces the imaging optics. Further optionally, the imaging optics include a front face facing the quantum sensor device, the microwave antenna being located between the front face and the sensor device.

[0093] The microwave antenna is arranged facing the optics side of the quantum sensor device. The microwave antenna may be located in a space between the sample area and the imaging optics. More generally, the microwave antenna is arranged such that the microwave radiation that interacts with the sample is microwave radiation that is reflected by the sample into the sensor area. Optionally, the microwave antenna is arranged such that an angle between a normal to the sample area and any virtual line connecting a point in the sample area to a point on the microwave antenna is less than 75°, 60°, or 45°. Further, it is possible that the microwave antenna is arranged such that an angle between a normal to the sample area and a direction of the microwave radiation emitted by the microwave antenna is less than 75°, 60°, or 45°.

[0094] The interface at which the microwave radiation is reflected within the sample can extend parallel to the sample area or sensor area. This requires a certain location of the microwave antenna in that the direction of the impinging microwave radiation is approximately the same as the orientation of the reflected microwave radiation. However, it has been found that electrical conductors in the sample often have a circular cross-section such that microwave radiation is reflected back into the sensor area as long as the microwave antenna is arranged in the half space on the side of the quantum sensor device relative to the sensor area.

[0095] With this embodiment, the colour sensors experience microwave radiation that is reflected back from the sample, for example from interfaces within the sample. Thus, with this arrangement of the microwave antenna, the device or spectroscopy device is sensitive for reflected microwave radiation.

[0096] In an optional embodiment of the devices and / or methods described herein, the microwave antenna and the optical sensor are arranged on opposing sides of the sample area so that the colour sensors are subjected to microwave radiation transmitted through the sample area.

[0097] With this embodiment, the microwave radiation interacting with the sample and sensed by the colour sensors may correspond to the microwave radiation that is transmitted through the sample, for example microwave radiation that is not reflected back by interfaces within the sample and / or absorbed by material within the sample. Thus, in contrast to the previous embodiment, the colour sensors may not experience the microwave radiation that is reflected back by the sample. Further, with this embodiment, different absorption properties of the sample can be measured.

[0098] In an optional embodiment of the devices and / or methods described herein, the microwave antenna is movable between a first position and a second position.

[0099] In further optional embodiment of the devices and / or methods described herein, the microwave antenna includes a first antenna section for emitting microwave radiation at a first position and a second antenna section for emitting microwave radiation at a second position, the controller being configured to control the microwave antenna to emit the microwave radiation either from the first antenna section or the second antenna section. In general, the microwave antenna may be configured to emit microwave radiation from at least two different positions. This may be implemented in that the microwave antenna is movable between a first position and a second position. For example, the microwave antenna is arranged on a rail or guide along which the microwave antenna can be moved. The micro wave met antenna may be manually moved or can be actuated, for example by an electric motor, to be moved from the first persistent to the position.

[0100] Alternatively, the microwave antenna may include at least two antenna sections each of which is configured to emit microwave radiation. The first antenna section is spatially offset from the second antenna section. The generator of the micro wave source may be configured to supply the microwave energy to the first antenna section and / or to the second antenna section. If the microwave radiation is emitted by the first antenna section, the microwave radiation originates from a different location compared to the situation in which the micro wave radiation is emitted by the second antenna section. The first antenna section and / or the second antenna section may be configured as described above, for example having the shape of a ring, loop, and / or an elongate rod.

[0101] In an optional embodiment of the devices and / or methods described herein, the controller is configured to further record the electronic signals received from the optical sensor for the microwave radiations generated at the first position and the second position, and to generate depth information of the sample area based on the differences between the respective electronic signals generated by microwave radiation emitted from the first position and the second position.

[0102] When the microwave radiation is emitted from the first position, the microwave radiation interacting with the sample has a different parameter set compared to the microwave radiation interacting with the sample that originates from the second position. This is due to the fact that the interaction of the micro wave radiation with the sample may be different depending on the orientation of the impinging microwave radiation and / or the microwave radiation has a different path (length) through from the first / second position to the sample and to the colour sensors. For example, when the impinging microwave radiation is reflected by the sample, this has an effect on the orientation and / or direction of the reflective micro wave radiation.

[0103] Thus, by generating a microwave radiation at two different positions, a stereo image of the sample can be provided. This may be due to the parallax effect which means that deviations in the recorded microwave radiations allow the generation of depth information and / or of a three-dimensional image. In other words, the generation of the microwave radiation at the first position and the second position provides the possibility to record three-dimensional information and / or depth information on the sample. For example, the microwave radiation generated by the microwave source may be modulated or pulsed such that the fluorescent light generated by the colour sensors may be encoded with the modulation or pulsation of the microwave radiation. This modulation or pulsed station can be used to determine the time of travel of the microwave radiation for generating depth information, for example at which depth the material interface at which the microwave radiation is reflected is located within the sample.

[0104] The depth information may correspond to information on how deep the material interacting with the microwave radiation (e.g. a reflecting interface) is located within the sample. This depth information may be generated by comparing the image based on the microwave radiation generated at the first position to the image based on the microwave radiation generated at the second position. For example, a lateral offset of a structure in the two images can be converted into a depth information.

[0105] In an optional embodiment of the devices and / or methods described herein, the colour sensors are nitrogen-vacancy centres in diamond so that the graph includes at least two local extrema corresponding to the polarization of the microwave radiation interacting with the sample. Optionally, the method further includes calculating two areas for each local extremum, wherein optionally the step of determining - for each pixel - changes in the electronic signals includes determining relative differences in the area of the local extrema.

[0106] It has been found that the resonance of the colour sensors depends on the polarisation of the microwave radiation interacting with the colour sensors (e.g. clockwise or anti -clockwise). For NV- centres for the colour sensors, it has been observed that there are two resonances each of which correspond to the resonance of the microwave radiation interacting with the colour sensors and having different polarization. Thus, for each polarisation of the microwave radiation, there is a specific resonance frequency which in turn shows that as a local extremum in the graph prepared as outlined above. Thus, if the microwave radiation is polarised, the graph only shows one extremum whereas there are two extrema for non-polarised microwave radiation. In the latter case, the intensities of the local extrema are equal if there is no preference in the polarisation of the microwave radiation interacting with the sample.

[0107] The microwave source may be configured to emit non-polarised microwave radiation. This may include that there is an equal distribution of the polarisation over the emitted microwave radiation. As known from the reflection of visible light at interfaces, the reflection may be more pronounced with one polarisation of the impinging light compared to the orthogonal polarisation of the impinging light. In other words, the reflection may be polarisation-dependent. The microwave source may be configured to emit polarised microwave radiation. The polarisation of the microwave radiation may be linear, circular or elliptical. The polarisation of the microwave radiation may be between 0° and 90° or between 30° and 60° or 45°.

[0108] The reflection within the sample may also be polarisation dependent for microwave radiation. This can be observed by a variation in the intensity of the two local extrema in the graph. For example, the intensity of the first local extremum decreases whereas the intensity of the second local extremum remains constant or increases. Thus, by calculating an area corresponding to each local extrema, polarisation of the microwave radiation interacting with the sample can be determined. This may be visualised in that the final image that shows the difference between the intensities of the two local extrema, for example the relative reduction of the area of the first local extremum compared to the area of the second local extremum. Alternatively, two different images can be generated each of which refer to the area of the local extremum. When analysing the sample, the two images showing the polarized reflection of the sample can be compared to extract further information, for example on the interface at which the microwave radiation was reflected. In other words, it is possible to gain further insights into the sample, namely on the polarisation of the reflected microwave radiation which can be indicative of the two materials at the interface.

[0109] In an optional embodiment of the devices and / or methods described herein, the device and / or the spectroscopy device further comprises a temperature sensor configured to measure a temperature of the colour sensor. Optionally, the controller is in data-communication with the temperature sensor and configured to record the temperature of the colour sensors for each image.

[0110] The fluorescent properties of the colour sensors, for example the resonance frequencies of the colour sensors, may depend on the temperature of the colour sensors. Thus, by monitoring the temperature of the colour sensors deviations that are based on the temperature of the colour sensors can be recorded and optionally used for correcting the determination of differences between consecutive measurements.

[0111] The temperature sensor may be in contact with the quantum sensor device for measuring the temperature thereof. Further, the temperature sensor may a contact-less temperature sensor. It is also possible that the temperature sensor measures the temperature around the quantum sensor device which may be indicative of the temperature of the quantum sensor device.

[0112] Examples of the invention will now be explained with reference to the accompanying drawings.

[0113] Fig. 1 shows a schematic view of a first embodiment of a device or a spectroscopy device; Fig. 2 shows a schematic view of a second embodiment of the device or the spectroscopy device;

[0114] Fig. 3 shows schematic diagram of the working principle of the device or the spectroscopy device of Fig. 1 or 2;

[0115] Fig. 4 shows an exemplary image of a wire generated with the device of Figs. 1 or 2, the darker the colour the higher is the intensity of the microwave radiation interacting with the integrated circuit; and

[0116] Fig. 5 shows a block diagram for a method for imaging a sample using the device of Figs. 1 or 2; and

[0117] Fig. 6 shows a block diagram for a method for spectroscopically analysing a sample using the spectroscopy device of Figs. 1 or 2.

[0118] Fig. 1 shows a first embodiment of a device 10a for imaging a sample 12. A similar setup which is shown in Fig. 2 may also be used for a spectroscopy device 10b for a spectroscopic analysis of a sample 12.

[0119] The device 10a and / or the spectroscopy device 10b comprises a sample holder 16, a quantum sensor device 18, a microwave source 20, a controller 24, imaging optics 28, an excitation light source 30, and / or an optical sensor 32. The sample holder 16 is configured to support the sample 12. Further, in this example, the sample holder 16 further supports the quantum sensor device 18 such that the sample 12 is in direct contact with the quantum sensor device 18.

[0120] The sample 12 may be an integrated circuit, a printed circuit board, an electric device and / or material interface. The imaging optics 28, the excitation light source 30, and / or the optical sensor 32 may provide a wide-field microscope 14 which may additionally comprise a beam splitter 26.

[0121] The quantum sensor device 18 includes a plurality of colour sensors which can be projected onto the optical sensor 32 by means of the imaging optics 28 which may include an objective. In other words, the wide-field microscope 14 allows the colour sensors to be projected onto the optical sensor 32 by means of wide-field imaging. The optical sensor 32 converts spatially resolved incident light into electrical or electronic signals. For example, the optical sensor 32 comprises a plurality of pixels, each pixel generating an electrical or electronic signal indicative of an intensity and / or a wavelength of the light impinging on the respective pixel. The plurality of electrical or electronic signals for each pixel can thus be used to image the sample 12 or provide spectroscopic analysis of the sample 12 as further outlined below. This can be done by the controller 24, which is in data communication with the optical sensor 32, for example to trigger the electrical or electronic signals of the optical sensor 32 and / or to drive the optical sensor 32. The controller 24 includes, for example, a processor and a memory. The memory may store one or more programs and / or algorithms that are executed by the processor. The controller 24 may also be in data communication with the excitation light source 30 to control the excitation light source 30. The excitation light source 30 may include one or more lasers or other devices for generating light. The light generated by the excitation light source 30 may be in the visible wavelength range, the infrared wavelength range, or the ultraviolet wavelength range. The excitation light source 30 may be configured to selectively generate light in a selected wavelength range, for example in a wavelength range that is absorbed by the colour sensors.

[0122] The light generated by the excitation light source 30 is coupled into the wide-field microscope 14 via the beam splitter 26 and directed to the objective of the imaging optics 28. The objective focuses the incident light onto the colour sensors in the quantum sensor device 18. The light emitted by the colour sensors is projected by the imaging optics 28 onto the optical sensor 32. The light beams in the beam paths described here do not have to be parallel, as shown in Figs. 1 or 2.

[0123] The excitation light source 30 may continuously emit excitation light which may result in so-called CW (continuous wave) measurements. Alternatively, the excitation light generated by the excitation light source 30 may be pulsed. For example, a first pulse of excitation light is emitted prior to the generation of the microwave radiation and a second pulse of excitation light is emitted after or during the generation of the microwave radiation. In this case, the emitted fluorescent light may only be imaged during the excitation of the second pulse.

[0124] The beam splitter 26 may be a semi-transparent mirror and / or a dichroic mirror. The choice of the type of beam splitter 26 depends on the light generated by the excitation light source 30 and which light is emitted and / or absorbed by the colour sensors.

[0125] The quantum sensor device 18 is supported by the sample holder 16. For example, the sample holder 16 has a hole in which the quantum sensor device 18 is embedded. A surface of the sample holder 16 may form a plane with a sample side of the quantum sensor device 18. The sample 12 can be placed on the quantum sensor device 18 and / or the sample holder 16. The area where the sample 12 can be placed on the sample holder 16 and / or supported by the sample holder 16 may be regarded as a sample area.

[0126] The quantum sensor device 18 may have a cuboid shape. The colour sensors may be arranged in a layer that is located on the side of the quantum sensor device 18 that contacts the sample 12. The layer of colour sensors may have a thickness sufficiently low so that the colour sensors can be imaged or projected onto the optical sensor 30. The colour sensors may be nitrogen-vacancy (NV) centres in 1 diamond. Thus, the quantum sensor device 18 may be entirely made from diamond. The area over which the colour sensors are provided within the quantum sensor device 18 may be considered a sensor area. The sensor area may be in direct contact with the sample 12.

[0127] The sample 12 is arranged close to or in contact with the colour sensors in the quantum sensor device 18. In particular, the colour sensors of the quantum sensor device 18 are in the near-field of the microwave radiation that is interacting with the sample 12. The near-field can be defined as a fraction of the wavelength. As the wavelength of the micro wave radiation is between 1 mm and 1 m, the distance between the sample 12 and the colour sensors in the quantum sensor device 18 may be between 1 pm and 1 mm, optionally between 10 pm and 100 pm.

[0128] The microwave source 20 may include a generator (not shown in the figures) and a microwave antenna. The microwave antenna may be arranged on the side of the sample holder 16 that faces the imaging optics 28. In other words, the microwave antenna and the imaging optics 28 are arranged on the same side of the sample holder 16 and / or the sample area which is the area where the sample 12 can be placed on the sample holder 16. In the embodiment of Fig. 1, the microwave antenna 20 is arranged in the space between the objective of the imaging optics 28 and the sample holder 16.

[0129] The microwave antenna may have a ring shape or a loop shape and / or may at least partially surround the quantum sensor device 18 such that microwave radiation emitted from the antenna penetrates the quantum sensor device 18, optionally from all sides, and can be reflected back from the sample 12 to the quantum sensor device 18. In this way, the colour sensors of the quantum sensor device 18 are subjected to the microwave radiation reflected by the sample as well as the microwave radiation directly emitted by the antenna of the microwave source 20.

[0130] The microwave source 20 can be controlled by the controller 24 and / or is in data communication with the controller 24. The microwave radiation generated by the microwave source 20 may be used to decrease and / or increase the absorption and / or emission of light by the colour sensors of the quantum sensor device 18. For example as schematically shown in Fig. 3, the micro wave radiation directly emitted by the antenna of the microwave source 20 may induce a population transfer in the excited states of the colour sensors because the energy of the microwave radiation corresponds to a gap in between two energy levels of the colour sensors. This may lead to a reduction of the emitted fluorescent light as shown in the graph depicted in Fig. 3. The three dips in the intensity of the fluorescent light or local extrema may correspond to the different orientations of the NV centres relative to the microwave radiation which results in different energy levels. The microwave radiation reflected from the sample 12 and interacting with the colour sensors of the quantum sensor device 18 may increase this population transfer, for example because the microwave radiation locally reflected an interface in the material (e.g. a conductive layer in a dielectric material) locally increases the intensity of the microwave radiation at the colour sensors. This may result in a local decrease in the intensity of the fluorescent light as schematically shown by the variation of the fluorescent light and in the graph depicted in Fig. 3. This change in the intensity of the fluorescent light may be spatially resolved and / or mirrors the structure within the sample 12 that reflects the microwave radiation. This is due to the fact that the colour sensors of the quantum sensor device 18 are in the near-field of the microwave radiation that is reflected by the sample 12. In this case, subwavelength resolution is possible compared to the far-field. Thus, it is possible to image structures within the sample 12 that reflect the microwave radiation.

[0131] The microwave radiation may be reflected by electrical conductors within the dielectric material of the sample 12. More generally, the microwave radiation may be reflected at interfaces between two different types of material, for example at the metal -dielectric interface. In this way, it is possible to image electrical conductors within an optically non-transparent material, such as semiconductor material. The differences in the intensity of the fluorescent light emitted by the colour sensors can be displayed in image as shown in Fig. 4. The darker the pixels of Fig. 4 are, the more microwave radiation is locally reflected back by structures within the sample 12. In case of Fig. 4, the sample 12 is a wire. The structure of the wire is clearly visible in Fig. 4.

[0132] The scale of fluorescence image is set to a baseline at which no or little microwave radiation is reflected back. This may correspond to the dip or decrease in the microwave radiation shown in the light grey line in the graph of Fig. 3. The baseline is depicted in white colour in Fig. 4. It is apparent from Fig. 4 that the imaging technique described herein is working.

[0133] The device 10a or the spectroscopy device 10b of the embodiment shown in Fig. 2 may have to same optional features, characteristics and / or embodiments as the device 10a or the spectroscopy device 10b, respectively, of the embodiment shown in Fig. 1, except for the differences described in the following:

[0134] The microwave antenna of the microwave source 20 is arranged on the side of the sample holder 16 that faces away from the imaging optics 28. In other words, the microwave antenna and the imaging optics 28 are arranged on the opposing sides of the sample area. In the embodiment of Fig. 2, the microwave antenna 20 is arranged above the sample holder 16. The microwave antenna of the microwave source 20 may include a first antenna section 20a and a second antenna section 20b. The first antenna section 20a may include two opposing elongate rods made from an electrically conductive material for emitting microwave radiation. The second antenna section 20b may also include two opposing elongate rods made from an electrically conductive material for emitting microwave radiation. The first antenna section 20a and a second antenna section 20b may be located rotated against each other by 90° around the optical axis. The generator of the microwave source 20 may be configured to supply the microwave energy to the first antenna section 20a or second antenna section 20b. Thus, the microwave radiation that interacts with the sample 12 originates from different positions which may be used to acquire depth information on the sample 12.

[0135] In an alternative embodiment not shown in figures, the micro wave antenna may be movable between a first position and a second position. For example, the microwave antenna may have the configuration of the first antenna section 20a as shown in Fig. 2. The microwave antenna may be movable from the position of the first antenna section 20a to the position of the second antenna section 20b as shown in Fig. 2. This may result in the same configuration for emitting microwave radiation. The controller 24 may be configured to control the position of the microwave antenna.

[0136] In the embodiment of Fig. 2, the microwave radiation interacting with the sample 12 is microwave radiation that is not absorbed and / or reflected by the sample 12. In other words, the microwave radiation that reaches the colour sensors depends on the absorption and / or reflection properties of the sample 12.

[0137] The microwave radiation generated by the microwave source 20 may be used to decrease and / or increase the absorption and / or emission of light by the colour sensors of the quantum sensor device 18. For example, the microwave radiation directly emitted by the antenna of the microwave source 20 may induce a population transfer in the excited states of the colour sensors. This may lead to a reduction of the emitted fluorescent light. The microwave radiation reflected from the sample 12 may result in a reduced intensity of the micro wave radiation interacting with the sample 12 because the microwave radiation is reflected by the interfaces of the sample 12 and may not reach the colour sensors. This may decrease the population transfer which may result in an increase in the intensity of the fluorescent light. This change in the intensity of the fluorescent light may be spatially resolved and / or mirrors that the structure within the sample 12 that reflects and / or absorbs the microwave radiation. This is due to the fact that the colour sensors of the quantum sensor device 18 are in the near-field of the microwave radiation that is reflected by the sample 12. In this case, sub-wavelength resolution is possible compared to the far-field. Thus, it is possible to image the structures within the sample 12 that reflect the microwave radiation. Further, in the embodiment of Fig. 2, the device 10a or the spectroscopy device 10b may include a magnetic source 22.

[0138] The magnetic source 22 may include a permanent magnet that generates a constant and / or homogeneous magnetic field within the sensor area. A permanent magnet may be provided for the device 10a for imaging the sample 12. The permanent magnet may induce a Zeeman split in the energy levels of the colour sensors.

[0139] In an alternative embodiment, the magnetic source 22 may include a generator (not shown in figures) and a coil for generating the magnetic field. Again, the generated magnetic field may be constant and / or homogeneous, for example within the sample 12 and / or the sensor area. The controller 24 may be configured to vary the orientation and / or the strength of the magnetic field between measurements. This means that, for a particular measurement, the magnetic field is constant and may be changed for the next measurement. A measurement may be considered as imaging the fluorescent light emitted by the colour sensors.

[0140] This alternative embodiment of the magnetic source 22 may be employed for the spectroscopy device 10b. The variation of the magnetic field between measurements can be used to manipulate the interaction of the microwave radiation with the sample 12, e.g. for instances in which the material of the sample 12 shows different properties of interaction with the microwave radiation depending on the strength and / or orientation of the magnetic field. The controller 24 may be configured to control the magnetic source 22 for varying the magnetic field between measurements.

[0141] A method of imaging the sample 12 and determining a quality parameter of the sample 12 is described in connection with the block the diagram of Fig. 5.

[0142] In step SI, the sample 12, which can be an integrated circuit, is placed in contact to or adjacent to the sensor area of the quantum sensor device 18. This may include laying the sample 12 on the sample holder 16, optionally on the quantum sensor device 18. Step SI may further include fixing the sample 12 to the sample holder 16, for example using a removable fastening means.

[0143] In optional step S2, a magnetic field is generated by the magnetic source 22. The magnetic field may be continuously generated over the next steps S3 to S5 or S3 to S6. The magnetic field may be generated for inducing a Zeemann-split in the energy levels of the colour sensors. Alternatively, the magnetic field is generated for changing the interaction of the microwave radiation with the colour sensors. In this case, the magnetic field has a first configuration which describes the orientation and / or the strength of the magnetic field. In step S3, excitation light is emitted by the excitation light source 30 and directed onto the colour sensors in the quantum sensor device 18 using the imaging optics 28, for example using the beam splitter 26 and the objective of the imaging optics 28. The excitation light may be continuously emitted. Alternatively, a pulse of the excitation light is generated for exciting the colour sensors.

[0144] In step S4, microwave radiation is emitted by the microwave source 20. The emitted microwave radiation may be characterised by a parameter set which describes the physical properties of the micro wave radiation. The parameters of the parameter set may relate to the frequency, the intensity, the phase, the modulation, the polarisation, and the like of the microwave radiation. The microwave radiation includes a parameter of a first value, for example a frequency of a certain value, which might correspond to a frequency of resonance with the colour sensors. The first value of the parameter may correspond to microwave radiation that is off resonance with the colour sensors such that the received fluorescent light corresponds to a base level.

[0145] The microwave radiation may be simultaneously emitted with the emission of the excitation light. Alternatively, a pulse of the microwave radiation is emitted after the pulse of the excitation light. In this case, a further pulse of the excitation light can be emitted during or after the pulse of the micro wave radiation.

[0146] In step S5, the fluorescent light emitted by the colour sensors is recorded. To this end, the fluorescent light emitted by the colour sensors is projected onto the optical sensor 32. The optical sensor 32 converts the received fluorescent light into electronic signals wherein the value of the electronic signals corresponds to the intensity and / or the wavelength of the received resonance light. This process is made for each pixel of the colour sensor 32. For example, if the colour sensor 32 includes 1032x1032 pixels, 1032x1032 electronic signals are generated. Each electronic signal may correspond to the fluorescent light emitted by the colour sensors located in the area corresponding to each pixel on the colour sensor 32.

[0147] In step S6, steps S3 to S5 are repeated with microwave radiation having a second value for the parameter. For example, the frequency of the microwave radiation is changed. The second value of the parameter may correspond to microwave radiation that is in resonance with the colour sensors such that the microwave radiation having the parameter of the second value induces a population transfer in the energy states resulting in a reduction of the intensity of the fluorescent light.

[0148] Step S6 may be repeated several times, for example if the frequency is swept between a lower boundary and an upper boundary. For example, as depicted in the graph of Fig. 3, the frequency is swept across the various extrema in the changes in the intensity of the emitted fluorescent light or, in other words, over the various resonances of the colour sensors. In this example, the magnetic field is held constant.

[0149] In an alternative to step S6, steps S2 to S5 are repeated with microwave radiation having a second value and the magnetic field having a second configuration. In other words, both the microwave field and the magnetic field are varied and for each variation an image of the colour sensors is generated. For example, it is possible to vary the values of parameter of the microwave radiation followed by a change from the first configuration to the second configuration of the magnetic field. Thereafter, the values of the parameter are varied as described above, for example including a sweep of the frequency.

[0150] In step S7, changes in the electronic signals over the various measurements made in step S6 are determined. This may include comparing - for each pixel - the value of the electronic signal generated in step S5 with the value of the corresponding electronic signals generated in step S6. Optionally, determining changes in the electronic signals may include generating a graph of the values of the electronic signals for each pixel as exemplified by the graph depicted in Fig. 3. Subsequently, an area over all dips or local extrema in the intensity can be calculated, for example relative to the baseline. Alternatively, for each dip or extremum in the intensity of the fluorescent light, an area can be calculated. The area or areas calculated indicate a change in the intensity of the fluorescent light for each pixel.

[0151] In step S8, an image is generated by assigning each pixel the difference value calculated in step S7. Thus, the image contains information in each pixel on the microwave radiation that is reflected by the sample 12 over the area that corresponds to the subgroup of colour sensors which in turn correspond to a single pixel. Thus, spatial information on the reflective properties of the sample 12 can be displayed in the image. As the microwave radiation penetrates the sample 12, the interfaces where the microwave radiation is reflected can be located within the sample 12 and not visible (and therefore cannot be imaged using optical microscopy).

[0152] Steps S6 and S7 may further include emitting the microwave radiation from the first antenna section 20a and from the second antenna section 20b and recording corresponding values of the electronic signals for each pixel. In this case, in step S7, depth information can be extracted when comparing the values of the electronic signals for each pixel in step S6. This is because an angle of orientation and / or parameter of the micro wave radiation interacting with the sample 12 is different depending on whether the microwave radiation is emitted from the first antenna section 20a or the second antenna section 20b. This is similar to the parallax effect known from optical imaging. Thus, in step S8, depth information may be obtained by comparing the two images generated in step S8. For example, a lateral offset of the same structure in the two images can be converted into depth information, e.g. how deep the structure is immersed in the sample 12.

[0153] In a further embodiment, for example when NV-centres are used for the quantum sensor device 18, the fluorescent light depends on the polarisation of the microwave radiation interacting with the sample 12. For example, two local extrema can be observed whereby each local extremum corresponds to the absorption of microwave energy by the colour sensors for a particular polarisation of the microwave radiation. If the microwave radiation is unpolarised, both extrema have to same amplitude. However, if the microwave radiation interacting with the sample 12 is polarised, for example the interaction with the reflecting interface within the sample 12, there might be a decrease in the amplitude of one of the two local extrema. This difference may be extracted in step S7 when determining changes in the electronic signals. Further, this difference may be displayed in the image generated in step S8. This polarisation information may be helpful in determining the type of interface, for example which materials constitute the interface.

[0154] In step S9, a quality parameter of the sample 12 is determined using the image generated in step S8. For example, the quality parameter refers to a constant thickness and / or width of a structure that reflects microwave radiation. Further, the quality parameter may refer to an aspect ratio of the width over a predetermined length. These types of quality parameters can be manually or automatically determined, for example by software analysis of the image. The quality parameter may be additionally compared to a predetermined threshold. If the quality parameter is above or below the predetermined threshold, this may indicate a fault in the sample 12. For example, if the thickness and / or width of structure identified in the image is below a predetermined threshold, this may indicate a disrupted conductor in the sample 12.

[0155] A method of spectroscopically analysing the sample 12 is described in connection with the block the diagram of Fig. 6.

[0156] In step SI, the sample 12, which can be an integrated circuit, is placed in contact to or adjacent to the sensor area of the quantum sensor device 18. This may include laying the sample 12 on the sample holder 16, optionally on the quantum sensor device 18. Step SI may further include fixing the sample 12 to the sample holder 16, for example using a removable fastening means.

[0157] In step S2, a magnetic field is generated by the magnetic source 22. The magnetic field is generated for changing the interaction of the microwave radiation with the colour sensors. The magnetic field has a first configuration which describes the orientation and / or the strength of the magnetic field. In step S3, excitation light is emitted by the excitation light source 30 and directed onto the colour sensors in the quantum sensor device 18 using the imaging optics 28, for example using the beam splitter 26 and the objective of the imaging optics 28. The excitation light may be continuously emitted. Alternatively, a pulse of the excitation light is generated for exciting the colour sensors.

[0158] In step S4, microwave radiation is emitted by the microwave source 20. The emitted microwave radiation may be characterised by a parameter set which describes the physical properties of the microwave radiation. The parameter of the parameter set may relate to the frequency, the intensity, the phase, the modulation, the polarisation, and the like of the microwave radiation. The microwave radiation includes a parameter of a first value, for example a frequency of a certain value, which might be a frequency which is in resonance of the colour sensors.

[0159] The microwave radiation may be simultaneously emitted with the emission of the excitation light. Alternatively, a pulse of the microwave radiation is emitted after the pulse of the excitation light. In this case, a further pulse of the excitation light can be emitted during or after the pulse of the micro wave radiation.

[0160] In step S5, the fluorescent light emitted by the colour sensors is recorded. Step S5 of the method of Fig. 6 corresponds to step S5 of the method of Fig. 5.

[0161] In step S6, steps S2 to S5 are repeated with the magnetic field having a second configuration and the microwave radiation is not changed. For example, the strength and / or the orientation of the magnetic field of the second configuration is changed compared to the magnetic field of the first configuration.

[0162] Step S6 may be repeated several times, for example if the strength and / or the orientation of the magnetic field are swept between a lower boundary and an upper boundary. Changes in the magnetic field may result in changes in the interaction of the microwave radiation with the sample 12. This may result in changes in the intensity of the fluorescent light emitted by the colour sensors.

[0163] It is also possible that in step S6 both the microwave radiation and the magnetic field are varied for example similar to step S6 of the method of Fig. 5.

[0164] In step S7, changes in the electronic signals over the various measurements made in step S6 are determined. This may include comparing - for each pixel - the value of the electronic signal generated in step S5 with the value of the corresponding electronic signals generated in step S6. Optionally, determining changes in the electronic signals may include generating a graph of the values of the electronic signals for each pixel as exemplified by the graph depicted in Fig. 3. Subsequently, an area over all dips or extrema in the intensity can be calculated, for example relative to the baseline. Alternatively, for each dip or extremum, an area can be calculated. The area or areas calculated indicate a change in the intensity of the fluorescent light for each pixel.

[0165] In step S8, an image is generated by assigning each pixel the difference value calculated in step S7. Thus, the image contains information in each pixel on the microwave radiation that interacts with the sample 12 over area that corresponds to the subgroup of colour sensors which in turn correspond to a single pixel. Thus, spatial information on the material properties of the sample 12 can be displayed in the image.

Claims

Claims1. Device for imaging a sample (12) including a material that interacts with microwave radiation, comprising a sample holder (16) for supporting the sample (12) in a sample area, a quantum sensor device (18) configured to be arranged adjacent to the sample area, the quantum sensor device (18) including colour sensors configured to absorb and / or emit light depending on a parameter of the microwave radiation interacting with the colour sensors, the colour sensors being arranged in a sensor area, an excitation light source (30) configured to generate excitation light configured to be directed to the sensor area for energetically exciting the colour sensors, an optical sensor (32) including a plurality of pixels and configured to generate electronic signals indicative of an intensity of the light emitted by the colour sensors, imaging optics (28) for projecting the sensor area onto the optical sensor (32), a microwave source (20) having a microwave antenna for emitting microwave radiation, the microwave source (20) being configured to generate microwave radiation that is characterized by a plurality of parameters, and a controller (24) in data-communication with the microwave source (20) and the optical sensor (32), wherein the sample holder (16) is configured to support the sample (12) such that the sensor area is in the near-field of the microwave radiation interacting with the sample (12), wherein the controller (24) is configured to vary at least one parameter of the microwave radiation at least between a first value and a second value, record - for each pixel - the electronic signals received from the optical sensor (32) for the microwave radiations generated using the first value and the second value, determine - for each pixel - changes in the electronic signals between the microwave radiations generated using the first value and the second value, and generate an image based on the changes for each pixel, the changes for each pixel indicating variations in the interaction of the micro wave radiation with the sample (12).

2. Device according to claim 1, further comprising a magnetic source (22) for generating a constant magnetic field through the sensor area, the magnetic source (22) configured to vary a strength of the magnetic field and / or an orientation of the magnetic field, wherein optionally the controller (24) is in data-communication with the magnetic source (22) and configured tovary the magnetic field between a first configuration and a second configuration that differs from the first configuration by the strength and / or orientation of the magnetic field, record - for each pixel - the electronic signals received from the optical sensor (32) for the microwave radiations generated using the first value and the second value and the magnetic fields generated using the first configuration and the second configuration, determine - for each pixel - changes in the electronic signals between the microwave radiations generated using the first value and the second value and magnetic fields generated using the first configuration and the second configuration, and generate the image based on the changes for each pixel, the changes for each pixel indicating local variations in the interaction of the microwave radiation with the sample area which are caused by the magnetic field having the first configuration or the second configuration.

3. Spectroscopy device for a spectroscopic analysis of a sample (12) including a material that interacts with microwave radiation, comprising a sample holder (16) for supporting the sample (12) in a sample area, a quantum sensor device (18) configured to be arranged adjacent to the sample area, the quantum sensor device (18) including colour sensors configured to absorb and / or emit light depending on a parameter of the microwave radiation interacting with the colour sensors, the colour sensors being arranged in a sensor area, an excitation light source (30) configured to generate excitation light configured to be directed to the sensor area for energetically exciting the colour sensors, an optical sensor (32) including a plurality of pixels and configured to generate electronic signals indicative of an intensity of the light emitted by the colour sensors, imaging optics (28) for projecting the sensor area onto the optical sensor (32), a microwave source (20) having a microwave antenna for emitting microwave radiation, a magnetic source (22) for generating a constant magnetic field through the sensor area, the magnetic source (22) configured to vary a strength of the magnetic field and / or an orientation of the magnetic field, a controller (24) in data-communication with the microwave source (20), the optical sensor (32), and / or the magnetic source (22), wherein the sample holder (16) is configured to support the sample (12) such that the sensor area is in the near-field of the microwave radiation interacting with the sample (12), wherein the controller (24) is configured to vary the magnetic field between a first configuration and a second configuration that differs from the first configuration by the strength and / or orientation of the magnetic field, record - for each pixel - the electronic signals received from the optical sensor (32) for the magnetic fields generated using the first configuration and the second configuration,determine - for each pixel - changes in the electronic signals between the magnetic fields generated using the first configuration and the second configuration, and generate the spectroscopic analysis based on the changes for one or more of the pixels, the changes for the one or more pixels indicating variations in the interaction of the microwave radiation with the sample area which are caused by the magnetic field having the first configuration or the second configuration.

4. Spectroscopy device according to claim 3, wherein the microwave source (20) is configured to generate microwave radiation that is characterized by a plurality of parameters, wherein optionally the controller (24) is in data-communication with the microwave source (20) and configured to vary at least one parameter of the microwave radiation at least between a first value and a second value, record - for each pixel - the electronic signals received from the optical sensor (32) for the microwave radiations generated using the first value and the second value and magnetic fields generated using the first configuration and the second configuration, determine - for each pixel - changes in the electronic signals between the microwave radiations generated using the first value and the second value and the magnetic fields generated using the first configuration and the second configuration, and generate the spectroscopic analysis based on the changes for each pixel, the changes for each pixel indicating local variations in the interaction of the micro wave radiations with the sample area which are caused by the magnetic field having the first configuration or the second configuration.

5. Device according to claim 1 or 2 or spectroscopy device according to claim 4, wherein the at least one parameter is a frequency of the microwave radiation, wherein the controller (24) is configured to sweep the frequency of the microwave radiation at least between the first value and the second value, record - for each pixel and for each frequency between the first value and the second value - the electronic signals received from the optical sensor (32), and generate - for each pixel - a graph based on the intensity of the received light depending on the frequency of the microwave radiation and calculate an area of a section of the graph, and determine the changes in the electronic signals based on the changes in the area of the section of the graph.

6. Device according to any one of the claims 1, 2 or 5 or spectroscopy device according to claim 4 or 5, wherein the microwave antenna and the imaging optics (28) are arranged on the same side of the sample area such that the colour sensors are subjected to microwave radiation reflected from the sample area, wherein optionally the microwave antenna is located on a side of the quantum sensor device that faces the imaging optics (28).

7. Device according to any one of the claims 1, 2 or 5 or spectroscopy device according to claim 4 or 5, wherein the microwave antenna and the optical sensor (32) are arranged on opposing sides of the sample area so that the colour sensors are subjected to microwave radiation transmitted through the sample area.

8. Device according to any one of the claims 1, 2 or 5 to 7 or spectroscopy device according to any one of the claims 4 to 7, wherein the microwave antenna is movable between a first position and a second position, or the microwave antenna includes a first antenna section (20a) for emitting microwave radiation at a first position and a second antenna section (20b) for emitting microwave radiation at a second position, the controller (24) being configured to control the microwave antenna to emit the microwave radiation either from the first antenna section (20a) or the second antenna section (20b), wherein the controller (24) is configured to further record the electronic signals received from the optical sensor (32) for the microwave radiations generated at the first position and the second position, and generate depth information of the sample based on the differences between the respective electronic signals generated by microwave radiation emitted from the first position and the second position.

9. Device according to any one of the claims 1, 2 or 5 to 8 or spectroscopy device according to any one of the claims 3 to 8, further comprising a temperature sensor configured to measure a temperature of the colour sensor, and wherein the controller (24) is in data-communication with the temperature sensor and configured to record the temperature of the colour sensors for each image.

10. Use of the device (10a) according to any one of the claims 1, 2 or 5 to 9 or of the spectroscopy device (10b) according to any one of the claims 3 to 9 for analysing an integrated circuit, printed circuit board, electronic device, and / or material interface.

11. Method for determining a quality parameter in an integrated circuit, comprising the steps ofa) placing the integrated circuit adjacent to a sensor area, the sensor area including colour sensors configured to absorb and / or emit light depending on a parameter of the microwave radiation interacting with the colour sensors, b) exciting the colour sensors by irradiating light onto the sensor area and projecting the sensor area onto an optical sensor (32) having a plurality of pixels, c) emitting microwave radiation from a microwave antenna towards the integrated circuit such that the integrated circuit is in the near-field of the microwave radiation interacting with the integrated circuit, the microwave radiation having a parameter of a first value, d) recording - for each pixel - electronic signals indicative of an intensity of the light emitted by the colour sensors, e) repeating steps b) to d) with microwave radiation having the parameter of a second value, f) determining - for each pixel - changes in the electronic signals between the microwave radiations generated using the first value and the second value, g) generating an image based on the changes for each pixel, the changes for each pixel indicating local variations in the interaction of the microwave radiation with the integrated circuit, and h) determining the quality parameter of the integrated circuit using the image.

Images