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

Abstract

Device (100) for analysing and / or processing a sample (102) with a particle beam (116), the sample (102) having an electrically conductive layer (142), comprising: a particle beam delivery unit (114) for delivering the particle beam (116) on a surface (118) of the sample (102), at least one electrode (148), which is configured to be arranged at a distance from the surface (118) of the sample (102) and, together with at least one portion (150) of the electrically conductive layer (142) of the sample (102), to form at least one capacitor (152) having a predetermined capacitance (C), and at least one potential source (154, 254), which is electrically conductively connected to the at least one electrode (148) in order to set the at least one electrode (148) to a predetermined electrical potential (U1, U2), wherein the predetermined capacitance (C) is determined on the basis of the predetermined electrical potential (U1, U2) of the at least one electrode (148) and a predetermined charge accumulation (Q) on the surface (118) of the sample (102) due to the delivered particle beam (116).

Description

[0001] DEVICE AND METHOD FOR ANALYSING AND / OR PROCESSING A SAMPLE WITH A PARTICLE BEAM

[0002] The present invention relates to a device and a method for analysing and / or processing a sample with a particle beam.

[0003] The content of the priority apphcation DE 10 2024 110 767.7 is incorporated entirely by reference.

[0004] Microlithography is used for producing microstructured component parts, for example integrated circuits. The microlithography process is carried out using a lithography installation, which comprises an illumination system and a projection system. The image of a mask (reticle) illuminated by means of the illumination system is projected by means of the projection system onto a substrate, for example a silicon wafer, which is coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection system, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0005] Driven by the desire for ever smaller structures in the production of integrated circuits, EUV lithography installations that use light having a wavelength in the range from 0.1 nm to 30 nm, in particular 13.5 nm, are currently under development. Since most materials absorb light at this wavelength, it is necessary in such EUV lithography installations to use reflective optical units, i.e. mirrors, instead of refractive optical units, i.e. lens elements, as used previously.

[0006] The mask (i.e. lithography mask) is used here for a multiplicity of exposures, which is why it is very important that the mask is free of defects and contaminants. Therefore, lithography masks are examined in regard to defects and contaminants at great expense. Attempts are then made to repair identified defects or to remove contaminants. The defects and contaminants may be extremely small and have sizes in the range of a few nanometres. Therefore, analysing and removing them requires devices with very high spatial resolution.

[0007] Processing devices are known that allow faulty structures on the mask to be etched away locally using a particle-beam-induced etching process, and missing structures on the mask to be added using a particle-beam -induced depositing process. These are, for example, modified scanning electron microscopes.

[0008] Processing devices are also known that can be used to selectively remove individual particles from a surface of the mask. For example, atomic force microscopes are used for this purpose. In this case, a particle is picked up by a measuring tip of the atomic force microscope and, adhering to the measuring tip, is removed from the mask surface.

[0009] Both particle-beam-induced etching and depositing processes and the removal of particles are usually monitored and supported by imaging techniques (e.g. image acquisition using a scanning electron microscope).

[0010] It is known that charging effects of the sample can significantly diminish the accuracy of a scanning electron microscope. In particular, the electron beam incident on a surface of the sample (primary beam) and the secondary electrons thereby released from the sample material can lead to charging of the sample surface. This means that a previously electrically neutral sample can be electrically charged. The charge accumulations on the sample surface can generate an electrical potential that can deform (e.g. defocus) and deflect the primary beam. This diminishes the positioning accuracy of the primary beam. In addition, the electrical potential generated by the charge accumulations on the sample surface can also influence the release of the secondary electrons (e.g. their number and trajectories). As a result, the image quahty of an image based on the secondary electrons can also be significantly diminished.

[0011] Additionally, when an atomic force microscope is used, the electrical potential generated by the charge accumulations on the sample surface means that discharge may occur when a tip of the atomic force microscope approaches the sample. This can damage or destroy the tip and / or sample.

[0012] EP 1 587 128 Bl proposes, in the case of a scanning electron microscope, arranging a screening element very close to the processing position, so that the charging of the sample and the impairment of the primary beam by charging of the sample are reduced.

[0013] Against this background, it is an object of the present invention to provide an improved device and an improved method for analysing and / or processing a sample with a particle beam.

[0014] According to a first aspect, a device for analysing and / or processing a sample with a particle beam is proposed. The sample has an electrically conductive layer. Additionally, the device comprises: a particle beam delivery unit for delivering the particle beam on a surface of the sample, at least one electrode, which is configured to be arranged at a distance from the surface of the sample and, together with at least one portion of the electrically conductive layer of the sample, to form at least one capacitor having a predetermined capacitance, and at least one potential source, which is electrically conductively connected to the at least one electrode in order to set the at least one electrode to a predetermined electrical potential, wherein the predetermined capacitance is determined on the basis of the predetermined electrical potential of the at least one electrode and a predetermined charge accumulation on the surface of the sample due to the delivered particle beam.

[0015] In particular, the predetermined charge accumulation on the surface of the sample corresponds to a predetermined electrical potential of the sample due to the (e.g., expected) accumulated charges on the surface of the sample. Further, the predetermined capacitance is, for example, determined on the basis of (i) a potential difference between the predetermined electrical potential of the at least one electrode and the predetermined electrical potential of the sample and (ii) the predetermined charge accumulation on the surface of the sample due to the delivered particle beam.

[0016] The at least one capacitor, which is formed from the at least one electrode and the at least one portion of the electrically conductive layer of the sample, allows electrical charges on the sample surface to be stored in the at least one capacitor. In other words, the sample is capacitively coupled to the at least one electrode, with the result that a voltage difference builds up and the charges on the sample surface can be stored in the region of the at least one capacitor.

[0017] This means that impairment of the particle beam incident on the sample surface (primary beam) by the charge accumulation at the sample surface can be reduced and / or avoided. For example, deformation of the particle beam, e.g. defocusing, and deflection of the particle beam due to a charge accumulation can be reduced and / or avoided. This can improve the positioning accuracy of the primary beam.

[0018] The capacitive coupling of the sample to the at least one electrode can additionally also reduce and / or avoid impairment of secondary particles by the charge accumulation at the sample surface. For example, an influence on the release of secondary particles (e.g. secondary electrons) from the sample material (e.g. the number of released secondary particles) and / or an influence on their trajectories after release can be limited or avoided. For example, it can thereby be achieved that variations in a detector signal generated on the basis of secondary particles over time can be reduced. This reduces interference with image information generated on the basis of the detector signal (e.g. a topographic contrast).

[0019] Consequently, the primary beam can be accurately controlled and the primary and secondary beams are subject to random and / or uncontrollable disturbing influences to a lesser extent. A high spatial resolution is thus possible, both during image capture, as in a scanning electron microscope, and during processing methods carried out using the particle beam, such as particle-beam-induced etching or deposition processes, ion implantation, and / or other structure-altering processes.

[0020] By way of example, the sample is a microlithographic lithography mask. For example, the sample is an EUV mask for EUV lithography (EUV:“extreme ultraviolet”, operating light wavelengths in the range of 1 - 30 nm, in particular 13.5 nm). For example, the sample is a reflective lithography mask. For example, the sample has structures (e.g. absorber structures). A structure size of the structures is, for example, in the range of 10 nm - 10 pm.

[0021] By way of example, the electrically conductive layer of the sample is a continuous electrically conductive layer. For example, the sample has a main plane of extension. For example, the electrically conductive layer of the sample extends over the entire main plane of extension of the sample and / or over a fraction of the main plane of extension (e.g., over a significant fraction such as more than 50%, more than 70% and / or more than 90% of the main plane of extension).

[0022] However, the electrically conductive layer of the sample may, for example, also be a non-continuous electrically conductive layer comprising two or more separate portions in the main plane of extension.

[0023] The sample may have the (continuous or non-continuous) electrically conductive layer at its surface. In other words, the electrically conductive layer of the sample may be the top layer of the sample in relation to the particle beam delivery unit. In this case, the electrically conductive layer has an exposed surface on which the particle beam is incident.

[0024] In other cases, a further, e.g. insulating or dielectric, layer may also be arranged above the (continuous or non-continuous) electrically conductive layer in relation to the particle beam delivery unit. In this case, the further layer has an exposed surface on which the particle beam is incident. For example, a thickness of the further layer is a few nanometres. The particle beam delivery unit is arranged above the sample, for example. The at least one electrode is, for example, configured to be arranged between the particle beam delivery unit and the sample. The at least one electrode is, for example, configured to be arranged above the top of the sample on which the particle beam is delivered.

[0025] The at least one electrode is arranged at a distance from the surface of the sample. The at least one electrode is thus also arranged at a distance from the electrically conductive layer of the sample.

[0026] In particular, the at least one electrode and the sample (e.g. the surface of the sample) are not in electrically conductive contact with one another. In addition, the at least one electrode and the electrically conductive layer of the sample are also not in electrically conductive contact with one another. In other words, the at least one electrode is arranged so as to be electrically insulated from the sample (e.g. from the surface of the sample or from the electrically conductive layer of the sample). That is to say, only an insulator or a dielectric is arranged between the at least one electrode and the sample (e.g. the surface of the sample or the electrically conductive layer of the sample). It can also be stated that the at least one electrode is free of electrically conductive contact with the sample and the sample is free of electrically conductive contact with the at least one electrode.

[0027] As the at least one electrode is arranged at a distance from the surface of the sample and from the electrically conductive layer of the sample, a change in the sample surface or the electrically conductive layer can be avoided.

[0028] For example, the distance between the at least one electrode and the surface of the sample is 300 gm or less, 200 gm or less, 100 gm or less, 50 gm or less, and / or 30 gm or less.

[0029] A dielectric is arranged between the at least one electrode, which forms a first plate of the at least one capacitor, and the at least one portion of the electrically conductive layer, which forms a second plate of the at least one capacitor.

[0030] The dielectric comprises vacuum, for example. If an insulating / dielectric layer is arranged above the electrically conductive layer, the dielectric comprises vacuum and the insulating / dielectric layer, for example. The analysis of the sample with the particle beam encompasses, for example, image capture of the surface of the sample using the particle beam (primary beam). For example, secondary particles are released from the sample material and detected in a detector. The device comprises a modified electron microscope, for example.

[0031] The processing of the sample with the particle beam encompasses, for example, particle-beam-induced etching processes in which a material is removed from the surface of the sample locally. The processing of the sample with the particle beam can also encompass particle-beam-induced depositing processes (deposition processes) in which a material is applied to the surface of the sample locally. Similar processes activated locally using the particle beam, such as forming a passivation layer or compacting a layer, may also be included in the processing of the sample.

[0032] The device may also comprise an atomic force microscope, for example. In this case, the atomic force microscope can be used for example to remove contaminants (e.g. particles, foreign bodies) from the sample. The removal process can be monitored by image capture from the surface of the sample using the particle beam (e.g. using an electron microscope).

[0033] The particle beam comprises charged particles, such as ions, electrons or positrons, for example. The delivery unit is an electron column, for example, which can deliver an electron beam having an energy in a range of 10 eV - 10 keV and a current in a range of 1 A - 1 pA. However, it can also be an ion source that delivers an ion beam. The particle beam is preferably focussed onto the sample surface, an irradiation region with a diameter in the range of 1 nm - 100 nm being achieved, for example. The particle beam composed of charged particles can be influenced, i.e. for example accelerated, directed, shaped and / or focussed, by means of electric and magnetic fields. For this purpose, the delivery unit can comprise a number of elements configured for generating a corresponding electric and / or magnetic field.

[0034] The at least one electrode has, for example, one or more plate shaped electrodes.

[0035] The predetermined charge accumulation on the surface of the sample due to the delivered particle beam is, for example, a charge accumulation predicted before the device is commissioned and / or before an analysis or processing process on the sample using the device is started. The predetermined charge accumulation includes, for example, a predetermined amount of charge and / or polarity of the charge (e.g. positive or negative charge) on the surface of the sample.

[0036] The device for analysing and / or processing a sample with a particle beam comprises, for example, a control device for controlling the particle beam delivery unit. The control device may, in addition or instead, also be configured for controlling other units of the device for analysing and / or processing a sample with a particle beam (e.g., a sample stage apparatus, a gas delivery unit etc.). The control device may, in addition or instead, also be configured for determining the predetermined charge accumulation on the surface of the sample.

[0037] In embodiments of the first aspect, the device for analysing and / or processing a sample with a particle beam comprises a device for detecting an instantaneous potential of the sample.

[0038] Furthermore, a control device of the device for analysing and / or processing a sample with a particle beam is, for example, configured for determining the predetermined charge accumulation on the surface of the sample based on the detected instantaneous potential of the sample.

[0039] In addition or instead, the device for analysing and / or processing a sample with a particle beam comprises, for example, a closed-loop control device for controlling the electrical potential of the at least one electrode, the closed-loop control device being configured to determine a deviation of the detected instantaneous potential of the sample from a target value of the potential of the sample, determine a manipulated variable on the basis of the determined deviation, and generate a control signal for driving the potential source of the at least one electrode on the basis of the determined manipulated variable.

[0040] A change in potential of the sample can be determined by (e.g. repeatedly) detecting the instantaneous potential of the sample. A change in potential of the sample can be caused, for example, by the particle beam introduced onto the sample. Additionally, closed-loop control (i.e. feedback control) of the electrode potential (i.e. the electrode voltage) can be used to compensate for the change in potential of the sample. The device for detecting the instantaneous potential of the sample is, for example, configured to detect a signal change at one or more detectors of the particle beam delivery unit (e.g. an altered offset voltage at an X-ray detector). Alternatively or additionally, the device for detecting the instantaneous potential of the sample comprises, for example, a tip of an atomic force microscope and / or a special voltage balance. Alternatively or additionally, the device for detecting the instantaneous potential of the sample is configured, for example, to detect a change in the capacitance and / or displacement currents (e.g. moving electrodes and / or connection of electrodes) of the at least one capacitor. Alternatively or additionally, the device for detecting the instantaneous potential of the sample comprises, for example, at least one current measuring unit, the potential source being electrically conduc- tively connected to the at least one electrode via the at least one current measuring unit in order to measure a current flowing between the potential source and the at least one electrode.

[0041] In embodiments of the first aspect, the device for analysing and / or processing a sample with a particle beam comprises: one or more actuators configured to adjust the distance between the at least one electrode and the surface of the sample on the basis of a predetermined distance. For example, the one or more actuators are configured to move the at least one electrode relative to the sample, with the result that the predetermined distance from the sample surface is adjusted.

[0042] For example, the device may also comprise multiple actuators configured to set a uniform distance between the at least one electrode and the surface of the sample. In other words, the multiple actuators may be configured to align the at least one electrode parallel to the surface of the sample (e.g. to eliminate an existing tilt between the at least one electrode and the surface of the sample).

[0043] In embodiments of the first aspect, the device for analysing and / or processing a sample with a particle beam comprises: one or more distance sensors configured to detect an instantaneous distance between the at least one electrode and the surface of the sample, and one or more actuators configured to adjust the distance between the at least one electrode and the surface of the sample on the basis of the detected instantaneous distance and a predetermined distance.

[0044] This allows the predetermined distance to be adjusted. Additionally, a collision between the at least one electrode and the surface of the sample can be prevented. This is particularly advantageous if the predetermined distance between the at least one electrode and the surface of the sample is very short.

[0045] For example, the device may also comprise multiple distance sensors configured to detect a tilt between the at least one electrode and the surface of the sample. Furthermore, the device may also comprise multiple actuators configured to eliminate the detected tilt.

[0046] A respective distance sensor comprises, for example, a capacitive distance sensor (e.g. one or more further electrodes, e.g. one or more further electrodes that are smaller than the at least one electrode that is part of the at least one capacitor). A respective distance sensor may also comprise, for example, a laser interferometer and / or a confocal microscope.

[0047] The one or more distance sensors are for example attached to the sample stage or to a housing of the particle beam delivery unit by means of at least one holder.

[0048] The one or more distance sensors are for example attached to the same holder (e.g. electrode holder) to which the at least one electrode that forms part of the at least one capacitor is attached. If, for example, the at least one electrode is attached to the sample stage by means of at least one electrode holder, the one or more distance sensors can also be attached to the sample stage by means of the at least one electrode holder, for example. If, alternatively, the at least one electrode is for example attached (e.g. by means of a further electrode holder) to a housing of the particle beam dehvery unit, the one or more distance sensors may for example also be attached to the housing by means of the at least one further electrode holder.

[0049] The one or more actuators are for example arranged on at least one holder that is attached to the sample stage or to a housing of the particle beam delivery unit. Consequently, the at least one holder is adjustable in relation to a distance from the particle beam dehvery unit or from the sample by means of the one or more actuators. Additionally or instead, the one or more actuators may also be arranged on the sample stage, with the result that the sample stage itself is height- adjustable (i.e. adjustable in relation to the distance from the particle beam dehvery unit).

[0050] For example, the device also comprises an open-loop and / or closed-loop control device configured to determine a manipulated variable on the basis of the detected instantaneous distance and the predetermined distance between the at least one electrode and the surface of the sample, and generate a control signal for driving the one or more actuators on the basis of the determined manipulated variable.

[0051] This allows the distance between the at least one electrode and the surface of the sample to be set to the predetermined distance (feedforward control) or automatically set to the predetermined distance (feedback control) even better.

[0052] According to one embodiment of the first aspect, the at least one electrode is configured to be arranged at a predetermined distance from the surface of the sample and / or from the electrically conductive layer of the sample, the predetermined distance defining a distance of the at least one capacitor. Furthermore, the at least one electrode and the at least one portion of the electrically conductive layer of the sample are arranged parallel to one another and so as to overlap one another in a region of overlap, the region of overlap defining a predetermined surface area of the at least one capacitor. Moreover, the predetermined distance and the predetermined surface area of the at least one capacitor define the predetermined capacitance of the at least one capacitor.

[0053] A "distance of the at least one capacitor" here means in particular a distance between the plates of the at least one capacitor (e.g. the distance between the at least one electrode that forms a first plate of the at least one capacitor and the at least one portion of the electrically conductive layer that forms a second plate of the at least one capacitor).

[0054] For example, the predetermined distance is a distance of a surface of the at least one electrode that faces the sample and the surface of the sample and / or a surface of the electrically conductive layer of the sample.

[0055] For example, the predetermined capacitance of the at least one capacitor is calculated using equation 1 below.

[0056] Equation 1:

[0057] Here, C denotes the capacitance, EO denotes the electrical field constant of the vacuum (EO = 8.854 e12As / Vm), ER denotes the relative permittivity of the dielectric (for vacuum as a dielectric, it holds that ER = 1), A denotes the predetermined surface area of the at least one capacitor and d denotes the distance between the plates of the at least one capacitor (e.g. the distance between the at least one electrode that forms a first plate of the at least one capacitor and the at least one portion of the electrically conductive layer that forms a second plate of the at least one capacitor).

[0058] For example, the surface area of the at least one capacitor is 0.200 m2or less, 0.100 m2or less, 0.010 m2or less, 0.008 m2or less, 0.006 m2or less, 0.004 m2or less, 0.003 m2or less, 0.002 m2or less, and / or 0.001 m2or less. In addition to or instead of the cited maximum magnitudes, the surface area of the at least one capacitor can also have a magnitude of at least 0.001 m2(minimum magnitude), for example.

[0059] As can be seen in equation 1 above, the predetermined capacitance of the at least one capacitor is also dependent on the relative permittivity ER of the dielectric in the capacitor gap in addition to the predetermined distance d and the predetermined surface area A of the at least one capacitor. However, the relative permittivity ER of the dielectric is equal to 1 for vacuum as a dielectric, and can usually be ignored for very thin insulating layers.

[0060] According to another embodiment of the first aspect, the at least one potential source is configured to deliver an earth potential, and the predetermined capacitance is determined on the basis of the earth potential as a predetermined electrical potential.

[0061] By keeping the at least one electrode at an earth potential by way of the potential source (e.g. an earth connection), a potential difference can build up between the at least one electrode and the sample (i.e. the plates of the at least one capacitor), which potential difference stores free charges at the surface of the sample.

[0062] An earth potential is in particular a potential of the earth or a potential equal to zero.

[0063] For example, the at least one electrode can be electrically conductively connected to a housing of the particle beam delivery unit, with the result that an earth potential of the housing is used as the at least one potential source.

[0064] According to another embodiment of the first aspect, the at least one potential source is configured to deliver a positive and / or negative potential, and the predetermined capacitance is determined on the basis of the corresponding delivered positive or negative potential as a predetermined electrical potential. By setting the at least one electrode to a positive and / or negative potential (i.e. a potential not equal to zero) by way of the potential source, a larger potential difference can be generated between the at least one electrode and the sample (i.e. the plates of the at least one capacitor). Thus, a lower capacitance of the at least one capacitor (e.g. a smaller surface area A and / or a greater distance d) is sufficient to store a specific amount of charge in the at least one capacitor.

[0065] The capacitance of the at least one capacitor can be expressed in particular as a function of the charge Q stored in the at least one capacitor and the potential difference U between the plates of the capacitor as equation 2 below.

[0066] Equation 2:

[0067] Equation 2 shows that when the potential difference U between the at least one electrode and the sample (i.e. the plates of the capacitor) is larger, a lower capacitance of the at least one capacitor is sufficient to store a specific amount of charge Q in the at least one capacitor. If a lower capacitance of the at least one capacitor is sufficient, then according to equation 1 the surface area A of the at least one capacitor can be designed to be smaller and / or the distance d of the at least one capacitor can be designed to be greater.

[0068] In embodiments, the device may be configured in such a way that the distance between the at least one electrode and the sample (i.e. the plates of the at least one capacitor) is variably adjustable. By adjusting the distance between the at least one electrode and the sample, a capacitance of the at least one capacitor can then still be adjusted after the device has been produced. In this case, the potential delivered by the potential source can be selected according to the set capacitance of the at least one capacitor.

[0069] In embodiments, the device may be configured in such a way that the surface area of the at least one capacitor (i.e. the region of overlap of the at least one electrode and the electrically conductive layer of the sample as a result of lateral displacement of the at least one electrode relative to the sample or relative to the electrically conductive layer of the sample) is variably adjustable. By adjusting the surface area of the at least one capacitor, the capacitance of the at least one capacitor can then still be adjusted after the device has been produced. In this case too, the potential delivered by the potential source can be selected according to the set capacitance of the at least one capacitor. For example, a state of charge of the sample can also be determined by changing the capacitance of the at least one capacitor. For example, the distance between the at least one electrode and the surface of the sample can be increased (e.g. gradually or continuously). Additionally, the state of charge of the sample can be detected, e.g. by means of an E-field probe and / or by detecting the detector signal during image acquisition by the electron microscope, during the change of distance. The positive and / or negative potential is in particular a potential that is not equal to an earth potential or not equal to zero.

[0070] The at least one potential source is, for example, a potential source for variably adjusting the delivered potential.

[0071] In embodiments, the sample can be set to a predetermined sample potential by dehvering a predetermined potential at the at least one electrode.

[0072] For example, the sample can be raised to a positive sample potential by delivering a predetermined potential on the at least one electrode. For example, a predetermined positive potential is delivered on the at least one electrode to raise the sample to a positive sample potential. If the particle beam is a beam of negatively charged particles, e.g. an electron beam, the positively charged sample can exert a braking action on the particle beam. This allows the speed of the negatively charged particles, e.g. the electrons, of the primary beam to be slowed down and the negatively charged particles to land on the surface of the sample with less energy. In this case, the positively charged sample can act as an electrical immersion lens.

[0073] For example, the sample can be set to a predetermined sample potential that corresponds (e.g. is of equal magnitude) to an electrical potential of a tip of an atomic force microscope that is used by dehvering a predetermined potential on the at least one electrode. If an atomic force microscope is used to analyse and / or process the sample, a tip of the atomic force microscope should have the same electrical potential as the sample when approaching and / or in contact with the sample. If the tip of the atomic force microscope is earthed, for example, the potential of the sample must also be earthed. Otherwise, the sample will be suddenly discharged, which can damage and / or destroy the sample.

[0074] According to another embodiment of the first aspect, the device comprises a sample holder for holding the sample. Additionally, the at least one electrode is attached to the sample holder, and / or the sample holder and the at least one electrode are configured to be moved with one another relative to the particle beam dehvery unit in order to analyse and / or process the sample.

[0075] Thus, the at least one electrode can be attached, for example, to an already existing structure of the device, namely the sample holder. Furthermore, the at least one electrode can be arranged in a peripheral region of the sample (e.g. an unused region of the sample) in a simple manner.

[0076] The sample holder can also have a sample stage.

[0077] According to one embodiment of the first aspect, the at least one electrode is attached to the sample holder so as to be mobile, with the result that at least part of the at least one electrode is able to be moved over the sample as seen from the particle beam delivery unit after the sample has been arranged on the sample holder.

[0078] Thus, the at least one electrode may be attached to the sample holder and still be arranged, at least in part, between the sample and the particle beam dehvery unit after the sample has been arranged on the sample holder.

[0079] For example, the at least one electrode is attached to the sample holder so as to be pivotable and / or foldable, with the result that at least part of the at least one electrode is pivotable or foldable over the sample after the sample has been arranged on the sample holder.

[0080] According to another embodiment of the first aspect, the surface of the sample has a used surface and an unused surface. Moreover, at least part of the at least one electrode is configured to be arranged above the unused surface of the sample as seen from the particle beam delivery unit, with the result that a region above the used surface is free of the at least one electrode.

[0081] Thus, the (e.g. entire) used surface of the sample can be analysed and / or processed with the particle beam, although part of the at least one electrode is arranged between the particle beam delivery unit and the sample.

[0082] For example, the used surface of the sample is a region of the sample that has microstructures that are meant to be imaged on a wafer in a microlithography process. The unused surface of the sample is for example a region of the sample that is free of such microstructures. For example, the unused surface of the sample is an edge region of the sample. According to another embodiment of the first aspect, the particle beam delivery unit comprises a housing and the at least one electrode is attached to the housing, and / or the at least one electrode is arranged at a fixed location relative to the particle beam delivery unit.

[0083] Thus, the at least one electrode can be attached, for example, to an already existing structure of the device, namely the housing of the particle beam delivery unit.

[0084] The at least one electrode is in particular attached to the housing of the particle beam delivery unit and / or arranged at a fixed location relative to the particle beam delivery unit in such a way that the particle beam can be delivered on the surface of the sample without hindrance from the particle beam delivery unit. A region between an outlet opening of the particle beam delivery unit for the particle beam and the surface of the sample is in particular free of the at least one electrode.

[0085] The sample is moved, for example relative to the particle beam delivery unit and to the at least one electrode, during the analysis and / or processing of the sample in order to analyse and / or process different regions of the sample. For example, the device has a sample holder that is configured to be moved relative to the particle beam delivery unit and to the at least one electrode in order to analyse and / or process the sample.

[0086] As the at least one electrode is attached to the housing of the particle beam delivery unit and / or arranged at a fixed location relative to the particle beam delivery unit, at least part of the at least one electrode can also be arranged above the used surface of the sample as seen from the particle beam delivery unit.

[0087] Additionally, the at least one electrode can be designed to be larger, i.e. can provide a larger capacitor surface area. This means that a capacitor having a larger capacitor capacitance can be provided.

[0088] According to another embodiment of the first aspect, the at least one electrode, as seen from the particle beam delivery unit, has a ring shape, a circular ring shape, a ring shape having a cutaway portion, a rotationally symmetrical shape in relation to an undeflected beam direction of the particle beam, a rectangular shape and / or a square ring shape.

[0089] According to another embodiment of the first aspect, the device has a current measuring unit, the potential source being electrically conductively connected to the at least one electrode via the current measuring unit in order to measure a current flowing between the potential source and the at least one electrode.

[0090] The current flowing between the at least one potential source and the at least one electrode depends on the current (e.g., net current) flowing between the particle beam delivery unit and the sample. Further, an amount of charge at the surface of the sample depends on the current flowing between the particle beam delivery unit and the sample.

[0091] Hence, the measured current flowing between the potential source and the at least one electrode over a period of time (measured with the current measuring unit) is an indication of the current flowing between the particle beam delivery unit and the sample over the period of time. Therefore, by measuring the current flowing between the potential source and the at least one electrode over the period of time, an amount of charge at the surface of the sample can be determined as the integral of the measured current over time.

[0092] It is noted that said current (e.g., net current) flowing between the particle beam delivery unit and the sample may be different from the current delivered by the particle beam delivery unit due to secondary particles emitted from the sample and / or backscattered primary particles. In other words, the current delivered by the particle beam delivery unit may have to be corrected by taking into account secondary particles emitted from the sample and / or primary particles backscattered from the sample. The current flowing between the particle beam delivery unit and the sample is then the net current of the current delivered by the particle beam delivery unit and the current resulting from emitted secondary particles and / or backscattered primary particles.

[0093] If the device for analysing and / or processing the sample comprises an atomic force microscope, a potential of the sample can be measured using a measuring tip of the atomic force microscope. Furthermore, in combination with a variable voltage source on the at least one electrode, the potential difference at the measuring tip of the atomic force microscope can be automatically set to zero to permit better processing of the sample using the atomic force microscope.

[0094] According to another embodiment of the first aspect, the particle beam delivery unit is configured to deliver the particle beam with a predetermined particle beam current for a predetermined period of time, and the determined charge accumulation is determined on the basis of the predetermined particle beam current and the predetermined period of time. In a first variant of this embodiment, the determined charge accumulation on the surface of the sample is determined based on the predetermined particle beam current and the predetermined period of time and, in addition, based on a determined current resulting from secondary particles emitted from the sample and / or primary particles backscattered from the sample. In particular, the predetermined particle beam current delivered by the particle beam delivery unit is corrected based on (i.e. by taking into account) the determined current resulting from emitted secondary particles and / or backscattered primary particles. In other words, in the first variant the determined charge accumulation on the surface of the sample is determined based on the corrected predetermined particle beam current and the predetermined period of time.

[0095] In a second variant of this embodiment, an assumption is applied according to which the predetermined particle beam current of the particle beam delivery unit equals by approximation the current flowing between the particle beam delivery unit and the sample. Thus, secondary particles emitted from the sample and / or primary particles backscattered from the sample - which are altering the net current flowing between the particle beam dehvery unit and the sample - are neglected by approximation in the second variant.

[0096] For example, the charge accumulation Q on the surface of the sample can be determined from the particle current I reaching the sample (e.g., according to the first variant, the net current IN flowing between the particle beam delivery unit and the sample! or according to the approximation of the second variant the predetermined particle beam current ID delivered by the particle beam dehvery unit) and the predetermined period of time At on the basis of the equations below. Current I is known to be equal to charge dQ per time di.

[0097] Equation 3:

[0098] For a constant current over time, equation 3 can be reformulated as follows.

[0099] Equation 4:

[0100] Equation 5- Q = I ■ At

[0101] Equation 5 can be used to calculate the charge accumulation Q on the surface of the sample from the particle current I reaching the sample (e.g., from the net current IN flowing between the particle beam delivery unit and the sample, or by approximation from the dehvered predetermined particle beam current ID) and the predetermined period of time At by Q = IN At or Q « ID • At.

[0102] Merely by way of illustration, 50 pA can be assumed as a maximum value for the particle current I reaching the sample (e.g., for the net current IN flowing between the particle beam delivery unit and the sample and / or for the current ID of the particle beam delivered by the particle beam dehvery unit). If the period of time At (e.g. analysis time and / or processing time) is one hour (3600 seconds), the amount of charge Q on the surface of the sample is thus 180 nC, as equation 6 shows.

[0103] Equation 6-

[0104] Q = I ■ At = 50 pA ■ 3600 s = 180 nC

[0105] For example, the particle beam delivery unit is configured to dehver the particle beam with a predetermined particle beam current of 5 nA or less, 1 nA or less, 500 pA or less, 100 pA or less, 50 pA or less, 40 pA or less, 30 pA or less, 25 pA or less, 20 pA or less, and / or 10 pA or less.

[0106] The predetermined charge accumulation on the surface of the sample and / or a momentary (instantaneous) charge accumulation on the surface of the sample can be determined, as described above, (i) based on the current flowing between the potential source and the at least one electrode and measured by use of the current measuring unit, and / or (ii) based on the predetermined particle beam current delivered by the particle beam delivery unit (either corrected by taking into account emitted secondary particle and / or backscattered primary particle, or by approximation without such a correction). The device for analysing and / or processing a sample with a particle beam may include for each of the above or below aspects (i) to (iv) a corresponding control device configured to carry out the respective aspect (i) to (iv).

[0107] In addition or instead to the devices / methods according to above aspects (i) and (ii), the predetermined charge accumulation on the surface of the sample and / or a momentary (instantaneous) charge accumulation on the surface of the sample can be determined (iii) based on changing the capacitance of the at least one capacitor, and / or (iv) based on a force measurement at the at least one electrode. In embodiment (iii), changing the capacitance of the at least one capacitor allows drawing conclusions on the charge accumulation on the surface of the sample.

[0108] In embodiment (iii), the capacitance of the at least one capacitor is, for example, changed based on changing the distance and / or the area of the at least one capacitor. Herein, the distance is, in particular, the distance between the at least one electrode and the surface of the sample / the electrically conductive layer of the sample. Further, the area is, in particular, the predetermined surface area of the at least one capacitor. Furthermore, the capacitance of the at least one capacitor is, for example, changed stepwise.

[0109] In embodiment (iii), for example for each value of the capacitance of the at least one capacitor a momentary (instantaneous) electrical potential of the sample is determined. Furthermore, the charge accumulation on the surface of the sample is then, for example, determined based on the determined dependence of the change of the momentary (instantaneous) electrical potential of the sample on the change of the capacitance of the at least one capacitor.

[0110] In embodiment (iv), a force (e.g., electrostatic force) acting on the at least one electrode is determined. The force acting on the at least one electrode allows drawing conclusions on the charge accumulation on the surface of the sample.

[0111] In embodiment (iv), the force acting on the at least one electrode is, for example, determined by configuring the at least one electrode as at least one spring-loaded electrode (e.g., with a free deflectable end) and determining a force -dependent deflection of the at least one spring-loaded electrode (e.g., of the free end of the at least one spring-loaded electrode). The deflection may, for example, be determined optically, interferometrically and / or by means of a laser.

[0112] Just as an example, the deflection of the at least one electrode may be detected similar as detecting a deflection of a cantilever supporting a manipulator tip of an atomic force microscope. For example, a deflection detection unit (e.g., a light pointer unit) may be provided - similar as for an atomic force microscope. The deflection detection unit comprises, for example, a laser source for emitting a laser beam towards the at least one electrode (e.g., a free end thereof) and a positionsensitive photodetector (e.g., with four photosensitive regions) to detect a reflected beam reflected from the at least one electrode (e.g., the free end thereof). In embodiment (iv), the force acting on the at least one electrode may also, for example, be determined piezoelectrically (e.g., the at least one electrode including one or more piezoelectric elements), and / or resistively (e.g., the at least one electrode including one or more strain sensors such as one or more strain gauges.

[0113] For determining the predetermined charge accumulation on the surface of a sample to be analysed and / or processed with the device (e.g., a first sample), optionally a further electrical electrode may be provided that is arranged in direct electrical contact (e.g., direct physical contact) with a (e.g., further) sample (e.g., a second sample and / or a test sample). In addition, the further electrical electrode is electrically connected to a further current measurement unit. In this case, the (e.g., expected) predetermined charge accumulation on the surface of the first sample caused by delivering a particle beam with a predetermined particle current on the surface of the first sample (causing a secondary electron emission), may be determined by using the second sample (e.g., test sample), electrically contacting the surface of the second sample with the further electrical electrode, delivering a particle beam with the same predetermined particle current on the surface of the second sample as planned for the first sample (causing the same secondary electron emission as expected for the first sample), and measuring a current flowing through the further electrical electrode using the further current measurement unit.

[0114] According to another embodiment of the first aspect, the predetermined capacitance is determined in such a way that a potential difference between the at least one electrode and the at least one portion of the electrically conductive layer of the sample is a factor of 10 lower, a factor of 100 lower, a factor of 200 lower, a factor of 300 lower, a factor of 500 lower and / or a factor of 1000 lower than an acceleration voltage of the particle beam delivery unit.

[0115] In other words, the predetermined capacitance is determined in such a way that the energy of the particle beam corresponding to the potential difference between the at least one electrode and the at least one portion of the electrically conductive layer of the sample is a factor of 10 lower, a factor of 100 lower, a factor of 200 lower, a factor of 300 lower, a factor of 500 lower and / or a factor of 1000 lower than an energy of the delivered particle beam.

[0116] For example, the predetermined capacitance is determined in such a way that the potential difference between the at least one electrode and the at least one portion of the electrically conductive layer of the sample is lower by said factor than the acceleration voltage of the particle beam delivery unit over the time of the sample processing.

[0117] Merely by way of illustration, the acceleration voltage of the particle beam delivery unit is 500 V or less, 300 V or less, 100 V or less and / or 50 V or less.

[0118] According to a second aspect, an arrangement is proposed which comprises a device and a sample as described above.

[0119] According to a third aspect, a method for analysing and / or processing a sample with a particle beam using a device as described above is proposed. The sample has an electrically conductive layer. Additionally, the method comprises the steps of a) delivering the particle beam on a surface of the sample, a charge accumulation appearing on the surface of the sample, b) setting at least one electrode, which is arranged at a distance from the surface of the sample, to a predetermined electrical potential, the at least one electrode, together with at least one portion of the electrically conductive layer of the sample, forming at least one capacitor having a predetermined capacitance, and the predetermined capacitance being determined on the basis of the predetermined electrical potential of the at least one electrode and a predetermined charge accumulation on the surface of the sample due to the delivered particle beam, and c) storing charges on the surface of the sample in the at least one capacitor.

[0120] For example, steps b) and c) are performed simultaneously.

[0121] The method may optionally comprise a step of discharging the sample. Discharging can be carried out e.g. once before step a) or repeatedly during steps b) and c). It is also possible to interrupt step b) and discharge the sample during the interruption.

[0122] The sample can be discharged using nitrogen, for example. Discharging of the sample can also be achieved, for example, by changing the acceleration voltage of the particle beam delivery unit (reversal of the secondary electron yield). In addition, the sample can be discharged using plasma generators, for example.

[0123] According to one embodiment of the third aspect, the method comprises, before step b): determining the charge accumulation on the surface of the sample, determining a target value for the capacitance of the at least one capacitor on the basis of the determined charge accumulation, and adjusting the determined capacitance of the at least one capacitor for the predetermined electrical potential of the at least one electrode by adjusting a distance and / or a surface area of the at least one capacitor, wherein the distance of the at least one capacitor is a distance of the at least one electrode from the surface of the sample and / or from the electrically conductive layer of the sample, and the surface area of the at least one capacitor is a region of overlap in which the at least one electrode and the electrically conductive layer of the sample, which are arranged parallel to one another, overlap one another.

[0124] The charge accumulation on the surface of the sample due to the delivered particle beam is also determined before step a), for example. The charge accumulation on the surface of the sample is, for example, predicted on the basis of planned settings of the particle beam delivery unit before the device is commissioned and / or before an analysis or processing process on the sample using the device is started.

[0125] However, the charge accumulation on the surface of the sample due to the delivered particle beam can also be determined during or after step a).

[0126] For example, determining the charge accumulation on the surface of the sample comprises determining an amount of charge and / or a polarity of the charge accumulation (e.g. positive or negative charge).

[0127] The amount of charge on the surface of the sample is determined, for example, by measuring a current flowing between the potential source and the at least one electrode over a period of time. The amount of charge at the surface of the sample can be determined as the integral of the measured current over time.

[0128] For example, the device has a current measuring unit, the potential source being electrically conductively connected to the at least one electrode via the current measuring unit in order to measure a current flowing between the potential source and the at least one electrode.

[0129] According to another embodiment of the third aspect, the method comprises, before step b): detecting an instantaneous electrical potential of the sample, and automatically adjusting the electrical potential of the at least one electrode, wherein a deviation of the detected instantaneous electrical potential of the sample from a target value of the electrical potential of the sample is determined, a manipulated variable is determined on the basis of the determined deviation, and the potential source of the at least one electrode is driven on the basis of the determined manipulated variable.

[0130] A change in potential of the sample can be determined by (e.g. repeatedly) detecting the instantaneous potential of the sample. A change in potential of the sample can be caused, for example, by the particle beam introduced onto the sample. Additionally, closed-loop control (i.e. feedback control) of the electrode potential (i.e. the electrode voltage) can be used to compensate for the change in potential of the sample.

[0131] "A" or "an" in the present case should not necessarily be understood as a restriction to exactly one element. Rather, there may also be multiple elements, for example two, three or more. Any other numeral used here should also not be understood as a restriction to exactly the stated number of elements. Rather, unless indicated otherwise, numerical deviations upwards and downwards are possible.

[0132] The embodiments and features described for the first aspect apply, mutatis mutandis, to the second and third aspects, and vice versa.

[0133] Further possible implementations of the invention also comprise non-explicitly mentioned combinations of features or embodiments described hereinabove or hereinafter with regard to the exemplary embodiments. A person skilled in the art will also add individual aspects as improvements or supplementations to the respective basic form of the invention.

[0134] Further advantageous embodiments and aspects of the invention are the subject matter of the dependent claims and of the exemplary embodiments of the invention described below. The invention is explained in greater detail hereinafter on the basis of preferred embodiments with reference to the accompanying figures.

[0135] Fig. 1 shows a schematic view of an exemplary embodiment of a device for analysing and / or processing a sample with a particle beam according to one embodiment;

[0136] Fig. 2 shows a partial view of a sample in cross-section according to one embodiment;

[0137] Fig. 3 shows an enlarged detail from Fig. 1, wherein a charge accumulation on a surface of the sample is illustrated; Fig. 4 shows a view similar to Fig. 3, wherein storage of the charge in a capacitor is illustrated;

[0138] Fig. 5 shows an enlarged partial view from Fig. 4;

[0139] Fig. 6 shows a view similar to Fig. 3 and 4, wherein a capacitor according to another embodiment is shown!

[0140] Fig. 7 illustrates a current measuring unit according to one embodiment, which can be used in the devices of Fig. 1 and 2 to 6;

[0141] Fig. 8 illustrates a mounting of an electrode of the capacitor on a sample stage of the device from Fig. 1;

[0142] Fig. 9 illustrates a mounting of an electrode of the capacitor on a housing of a particle beam delivery unit of the device from Fig. 1;

[0143] Fig. 10 to 17 show different embodiments of the at least one electrode of the device from Fig. 1;

[0144] Fig. 18 shows a flowchart for a method for analysing and / or processing a sample with a particle beam according to one embodiment; and

[0145] Fig. 19 illustrates a control loop for controlling a potential of at least one electrode of the device from Fig. 1.

[0146] In the figures, identical or functionally identical elements have been provided with the same reference signs, unless indicated otherwise. It should also be noted that the representations in the figures are not necessarily to scale.

[0147] Fig. 1 shows a schematic view of an exemplary embodiment of a device 100 for analysing and / or processing a sample 102. The device 100 has a housing 104. An interior of the housing 104 is evacuable to a residual gas pressure of 1 - 1010mbar, e.g. 105- 109mbar, by means of a vacuum pump 106, for example.

[0148] The device 100 is configured in particular for analysing and / or processing samples 102 in the form of lithography masks. By way of example, the device 100 is a verification and / or repair tool for lithography masks, in particular for lithography masks for EUV (extreme ultraviolet) lithography. The reference sign 200 denotes an arrangement comprising the device 100 and a sample 102.

[0149] The device 100 additionally comprises, for example, a sample stage apparatus 108 having a sample stage 110 for holding the sample 102. The sample stage 110 is preferably mechanically damped and / or held in a manner decoupled from the housing 104 by means of a holding apparatus 112 of the sample stage apparatus 108. The sample stage apparatus 108 can furthermore comprise a positioning unit (not shown) by means of which the sample stage 110 is movable in the three spatial directions x, y and z, for example, and is rotatable about at least one axis (e.g. the z axis in Fig. 1), for example. By way of example, a position of the sample stage 110 and thus of the sample 102 can therefore be adjusted with an accuracy of a few nanometres.

[0150] The device 100 furthermore comprises a particle beam delivery unit 114 for delivering a particle beam 116 on a surface 118 of the sample 102. The particle beam 116 is in particular a beam of charged particles, e.g. electrons or ions. The particle beam 116 can be used to examine (e.g. image) and / or process (e.g. in a particle-beam-induced etching or depositing process) the sample 102, e.g. the sample surface 118.

[0151] The particle beam delivery unit 114 has an electron column 120, for example. The electron column 120 comprises an electron source 122 for delivering the particle beam 116 in the form of an electron beam. The electron column 120 also comprises one or more detectors 124. A ring detector 124 is shown merely by way of illustration in Fig. 1. The one or more detectors 124 are used, for example, for detecting secondary electrons 126 (Fig. 3) backscattered from the sample 102. The electron column 120 preferably has a dedicated vacuum housing 128 within the vacuum housing 104. The vacuum housing 128 is evacuated to a residual gas pressure of 10’7mbar - 1010mbar, for example. The electron beam 116 from the electron source 122 passes through this vacuum until it emerges from the vacuum housing 128 through an opening 130 on the underside 132 thereof and then hits the surface 118 of the sample 102.

[0152] However, the particle beam delivery unit 114 may also be configured for delivering an ion beam - in addition to or in place of the electron beam 116. In this case, the device comprises an ion source (not shown).

[0153] There may also be provision for one or more further detectors (in addition to or instead of the ring detector 124), e.g. for secondary electrons 126 (not shown). The device 100 may optionally also have a gas delivery unit 134. The gas delivery unit 134 is used for supplying process gases via a gas pipe 136 into the region of a focal point of the particle beam 116 (e.g. electron beam) on the sample 102. The particle beam dehvery unit 114, e.g. the electron column 106, can carry out particle-beam-induced processing processes (e.g. electron-beam-induced processing (EBIP) processes) in conjunction with the supplied process gases. This comprises in particular depositing material on the sample 102 and / or etching material therefrom.

[0154] The device 100 furthermore has a control unit 138 that suitably drives the particle beam dehvery unit 114, the sample stage apparatus 108 and / or the gas dehvery unit 106.

[0155] Fig. 2 shows a partial view of a cross-section of an illustrative sample 102. The sample 102 in the example of Fig. 2 comprises a substrate 140 and an electrically conductive layer 142 arranged thereon. A dielectric layer 144 is furthermore arranged on the electrically conductive layer 142. The sample 102 has, for example, a main plane of extension G (Fig. 10), which corresponds to an xy plane in the figures. Furthermore, the electrically conductive layer 142 extends, for example, over the entire main plane of extension G. The sample 102 additionally has, for example, microstructures (e.g. absorber structures) (not shown in Fig. 2).

[0156] As illustrated in Fig. 3, the particle beam 116 (primary beam) incident on the surface 118 of the sample 102 and the secondary electrons 126 thereby released from the sample material can lead to charging Q of the sample 102 in the vicinity of the sample surface 118. This means that a previously electrically neutral sample 102 can be electrically charged. The charge accumulations Q on the sample surface 118 can deform (e.g. defocus) the primary beam 116 or deflect it from a target position. This diminishes the positioning accuracy of the primary beam 116. In addition, charge accumulations Q on the sample surface 118 can also influence the release of the secondary electrons 126 (e.g. their number and trajectories 146). Consequently, the image quality of an image of the sample 102, which is reconstructed by means of secondary electrons 126 detected e.g. by the detector 124 (Fig. 1), may also be diminished.

[0157] In order to reduce the influence of charge accumulations Q on the sample surface 118 on the primary beam 116 and the secondary beam 126, 146, the device 100 has at least one electrode 148, which is arranged at a distance d from the surface 118 of the sample 102, as shown in Fig. 3. The at least one electrode 148, together with at least one portion 150 of the electrically conductive layer 142 of the sample 102, forms at least one capacitor 152. A capacitance of the capacitor 152 is identified by the reference sign C.

[0158] Additionally, the device 100 comprises at least one potential source 154, which is electrically conductively connected to the at least one electrode 148. An electrical connection of the at least one potential source 154 to the at least one electrode 148 is identified by the reference sign 156 in Fig. 3. The potential source 154 applies a potential U1 to the at least one electrode 148. The potential source 154 in the example of Fig. 1 and 3 is an earth connection that keeps the at least one electrode 148 at an earth potential UM (Ul = UM).

[0159] The at least one electrode 148, together with the at least one portion 150 of the electrically conductive layer 142 of the sample 102, forms the at least one capacitor 152 having a predetermined capacitance C. The capacitance C is determined in such a way that an amount of charge Q appearing on the sample surface 118 can be stored in the capacitor 152 as a result of the build-up of an electric field E between the plates of the capacitor (Fig. 4).

[0160] In particular, the at least one electrode 148 and the at least one portion 150 of the electrically conductive layer 142 of the sample 102 are arranged parallel to one another and so as to overlap one another in a region of overlap 158, as illustrated in Fig. 5. The region of overlap 158 defines a surface area A of the capacitor 152.

[0161] It can also be stated that a portion 160 of the at least one electrode 148 in the region of overlap 158 forms a first plate Pl of the capacitor 152. In addition, the at least one portion 150 of the electrically conductive layer 142 in the region of overlap 158 forms a second plate P2 of the capacitor 152. A dielectric 162 is arranged between the plates Pl and P2. The dielectric 162 here comprises the vacuum that prevails within the housing. If the sample 102, as shown by way of illustration in Fig. 2, has another dielectric layer 144 above the electrically conductive layer 142, the dielectric 162 between the plates Pl, P2 also comprises the dielectric layer 144 in addition to the vacuum. Since the dielectric layer 144 is usually very thin (e.g. a few nanometres), it can usually be ignored when calculating the capacitance C of the capacitor 152.

[0162] The capacitance C is determined in such a way that an amount of charge Q appearing on the sample surface 118 can be stored in the capacitor 152 as a result of the build-up of an electric field E between the plates of the capacitor (Fig. 4). To determine the required capacitance C of the capacitor 152, so that the amount of charge Q appearing on the sample surface 118 can be stored in the capacitor 152, the amount of charge Q is first determined. For this purpose, a flow of current I (Fig. 4) on the sample surface 118 and a duration of this flow of current I are estimated, for example on the basis of the equations below.

[0163] Current I is known to be equal to charge dQ per time di, as formulated in equation 3.

[0164] Equation 3:

[0165] For a constant current over time, equation 3 can be reformulated as follows.

[0166] Equation 4

[0167] Equation 5

[0168] Q = I ■ At

[0169] Equation 5 can be used to calculate the charge accumulation Q on the sample surface 118 from the flow of current I onto the sample surface 118 (e.g., from a predetermined particle beam current delivered by the particle beam delivery unit, optionally corrected with respect to emitted secondary particles and / or backscattered primary particle) and the predetermined period of time At.

[0170] Merely by way of illustration, 50 pA can be assumed as a maximum value for the current I of the particle beam. If the period of time At (e.g. processing time) is one hour (3600 seconds), the amount of charge Q on the surface of the sample is thus 180 nC.

[0171] Equation 6'

[0172] Q = I ■ At = 50 pA ■ 3600 s = 180 nC

[0173] In particular, secondary electrons 126 are released from the sample material by the incident primary beam 116, for example, with the result that the sample surface 118 is positively charged (Fig. 3). The capacitive coupling using the at least one electrode 148 moves the positive charges Q in the direction of the capacitor 152 (Fig. 4) (current I). A potential difference AU and thus an electric field E then build up between the plates Pl, P2 of the capacitor. This allows the charge Q on the sample surface 118 to be stored in the capacitor 152.

[0174] That is to say, the charge Q is removed by the capacitor 152 from a processing region 164 of the sample 102 and stored in a capacitor region 166 of the sample 102. In particular, there is no electrically conductive connection between the sample 102 and the at least one electrode 148. Furthermore, the charge Q is also not completely removed from the sample 102. Rather, the charge Q is displaced only on the sample 102 (from the processing region 164 to the capacitor region 166), and so it does not influence or barely influences the primary beam 116 and the secondary beam 126, 146.

[0175] In order to store, for example, an amount of charge of 180 nC, as estimated for the above example, in the capacitor 152, the predetermined electrical potential UM of the at least one electrode 154 and the capacitor surface area A and the capacitor distance d are taken into account or adjusted accordingly.

[0176] For example, a maximum potential difference AU between the plates Pl, P2 is selected in such a way that it is low compared to an acceleration voltage UH of the particle beam delivery unit 114. Merely by way of illustration, an acceleration voltage UH of the particle beam delivery unit 114 is 300 V, for example (i.e. an energy of the electrons of the primary beam 116 is e.g. 300 eV). Furthermore merely by way of illustration, a maximum potential difference AU between the plates Pl, P2 of 1 V is selected, which can be regarded as low compared to an acceleration voltage UH of 300 V.

[0177] For example, the predetermined capacitance C of the capacitor is calculated using the following equation:

[0178] Here, co denotes the electric field constant of the vacuum (co = 8.854 e12As / Vm), 8R denotes the relative permittivity of the dielectric 162 (for vacuum as a dielectric, it holds that C = 1), A denotes the predetermined surface area of the capacitor 152 and d denotes the distance between the plates Pl, P2 of the capacitor (e.g. the distance d between the at least one electrode 148 and the at least one portion 150 of the electrically conductive layer 142).

[0179] In other words, the device 100 having the at least one electrode 148 may be designed and / or configured in such a way that the surface area A and the distance d are selected so that the resulting capacitance of the capacitor C is sufficient to store the predetermined amount of charge Q (e.g. 180 nC in the example above). In the cross-sectional view of Fig. 3, only a side face al is visible from the surface area A. For example, the surface area A is a rectangular surface area A (e.g. Fig. 10) that results from multiplying the side lengths al, a2 of the rectangle. The side length al is 0.02 m, for example, and the side length a2 is 0.15 m, for example. This results in an illustrative surface area of 0.003 m2. Other values for al, a2 and therefore A can also be applied.

[0180] Figures 1 and 3 to 5 show a potential source 154 that has an earth connection to keep the at least one electrode 148 at an earth potential U1 = UM. However, the potential source 254 may also be configured to deliver a positive and / or negative potential U2 that is not equal to zero, as shown in Fig. 6.

[0181] Fig. 6 shows the sample 102 and the at least one electrode 248 (similar to the at least one electrode 148 in Fig. 1 and 3 to 5) of the device 100, which is arranged at a distance from the sample 102. In the embodiment of Fig. 6, the at least one potential source 254 is configured to deliver a positive and / or negative potential U2 not equal to zero.

[0182] Thus, a larger potential difference AU2 can be generated between the at least one electrode 248 (corresponding to plate Pl in Fig. 5) and the sample 102 (corresponding to plate P2 in Fig. 5). Thus, a lower capacitance C of the capacitor 252 (e.g. a smaller surface area A and / or a greater distance d) is sufficient to store a specific amount of charge Q. This follows directly from the following equation, which indicates the capacitance C (C) of the capacitor 252 as a function of the charge Q stored in the capacitor 252 and the potential difference U (AU2) between the plates Pl, P2 of the capacitor 252:

[0183] The equation shows that when the potential difference U (AU2) between the plates Pl, P2 of the capacitor 252 is larger, a lower capacitance C (C) of the capacitor 252 is sufficient to store a specific amount of charge Q in the capacitor 252. If a lower capacitance C (C) of the capacitor 252 is sufficient, then, for example, the surface area A of the capacitor 252 can be designed to be smaller and / or the distance d of the capacitor 252 greater.

[0184] Merely by way of illustration, the sample 102 can be raised to a positive potential using the potential source 254 and the capacitive coupling to the at least one electrode 248. If the particle beam 116 is a beam of negatively charged particles, e.g. an electron beam, the positively charged sample 102 can exert a braking action on the particle beam 116. This means that an electrical immersion lens can be provided, for example. In addition, the detection efficiency can also be changed because the braking action on the primary beam 116 simultaneously has a repulsive effect on the secondary electrons 126. Thus, the secondary electrons 126 are then increasingly incident on the detector(s) 124 in the particle beam delivery unit 128.

[0185] As shown in Fig. 7, the device 100 can optionally have a current measuring unit 370. Additionally, the potential source 354 is electrically conductively connected to the at least one electrode 348 via the current measuring unit 370 (electrical connection 356). The current measuring unit 370 can be used to measure a current flowing between the potential source 354 and the at least one electrode 348. This allows the charge accumulation Q at the surface 118 of the sample 102 to be determined.

[0186] The current measuring unit 370 shown in Fig. 7 can be used for any electrode and potential source shown herein.

[0187] The electrodes 148, 248, 348 described herein may be attached, for example, to the sample stage 110 (Fig. 1, 8), to the particle beam dehvery unit 128 (Fig. 9) or to another structure (not shown) of the device 100.

[0188] Furthermore, Fig. 7 shows a potential source 354 by way of illustration, which - similarly to the potential source 254 in Fig. 6 is configured to deliver a positive and / or negative potential U2 that is not equal to zero. In other examples, however, the potential source 354 in Fig. 7 - similarly to the potential source 154 in Figures 1 to 3 can, for example, also be an earth connection that keeps the at least one electrode 348 at an earth potential UM.

[0189] The device 100 can optionally also have a closed-loop control device RE (Fig. 19) for controlling the electrical potential U2 of the at least one electrode 248, 348. Fig. 19 shows a control loop FB that illustrates feedback control for controlling the electrical potential U2 for the at least one electrode 248, 348.

[0190] The device 100 comprises, for example, a device (e.g. the current measuring unit 370 in Fig. 7 or another device) for detecting an instantaneous potential y(t) of the sample 102 (Fig. 19). The device 100 additionally comprises the closed-loop control device RE (Fig. 19). The closed-loop control device RE is configured to determine a deviation e(t) of the detected instantaneous potential y(t) of the sample 102 from a target value r(t) for the potential of the sample 192. Furthermore, the closed-loop control device RE is configured to determine a manipulated variable u(t) on the basis of the determined deviation e(t) and to drive the potential source 254, 354 of the at least one electrode 248, 348 on the basis of the determined manipulated variable u(t).

[0191] In Fig. 19, a controlled system in the control loop FB is identified by the reference sign RS. The controlled system RS comprises, for example, a sensor system (e.g. the current measuring unit 370 in Fig. 7 or another device for detecting the instantaneous potential y(t) of the sample 102), an actuator system (e.g. the potential source 254, 354), the sample 102 and the at least one electrode 248, 348.

[0192] In addition, a disturbance variable (e.g. the particle beam 116 incident on the sample 102) that changes a potential of the sample 102 is identified by the reference sign d(t) in Fig. 19.

[0193] The closed-loop control device RE or the control loop FB can be used to compensate for a change in potential of the sample 102 imposed by the disturbance variable d(t) by controlling the electrode potential of the at least one electrode 248, 348.

[0194] Fig. 8 shows an embodiment in which the at least one electrode 448 is attached to the sample stage 410 (sample holder). The at least one electrode 448 is for example attached to the sample stage 410 by means of at least one electrode holder 472.

[0195] For example, in this case, the sample stage 110 containing the sample 102 and the at least one electrode 448 can be moved (by means of the positioning unit of the sample stage apparatus 108, Fig. 1) with one another relative to the particle beam delivery unit 114. The sample stage 110 containing the sample 102 and the at least one electrode 448 can be moved in order to analyse and / or process different regions of the sample 102 using the particle beam 116.

[0196] In the example of Fig. 8, the at least one electrode 448 is attached to the sample stage 410 so as to be mobile. The mobile attachment may comprise, for example, a hinge or joint 474 for pivoting (folding) the electrode holder 472 (see arrow K). This means that at least part of the at least one electrode 448 can be moved (e.g. pivoted or folded) over the sample 102 as seen from the particle beam delivery unit 114 after the sample 102 has been arranged on the sample stage 110. Alternatively, the sample 102 - although not shown in the figures - can also be arranged on the sample stage 110 by pushing it in laterally (parallel to the x direction in Fig. 8). Moreover, the at least one electrode 448 can then be brought closer to the sample 102 from above (in the negative z direction in Fig. 8).

[0197] The device 100 may, for example, comprise one or more actuators (not shown) for moving the at least one electrode 448, e.g. for pivoting (folding) the electrode holder 472 (see arrow K).

[0198] Fig. 9 shows an embodiment in which the at least one electrode 548 is attached to a housing 528 of the particle beam delivery unit 114 (Fig. 1). The at least one electrode 548 is for example attached to the housing 528 by means of at least one further electrode holder 572. The shape and design of the housing in Fig. 9 is merely illustrative. The housing 528 to which the at least one electrode 548 is attached may also have a shape and / or design like the housing 128 shown in Fig. 1 or a different shape and / or design.

[0199] The at least one electrode 548 is in particular attached to the housing 528 of the particle beam delivery unit 114 in such a way that the particle beam 116 can reach the surface 118 of the sample 102 without hindrance from the particle beam delivery unit 114. A region between an outlet opening 530 of the particle beam delivery unit 114 for the particle beam 116 and the surface 118 of the sample 102 is in particular not covered by the at least one electrode 548.

[0200] By attaching the at least one electrode 548 to the housing 128, 528 of the particle beam delivery unit 114 (Fig. 1), the at least one electrode 548 is for example arranged at a fixed location relative to the particle beam delivery unit 114. This means that part of the at least one electrode 548 can also be arranged above a used surface of the sample 102 as seen from the particle beam delivery unit 114. Additionally, the at least one electrode 548 can be designed to be larger, and so a larger capacitor surface area A is available. This means that a capacitor having a larger capacitance C can be provided.

[0201] Although not shown in the figures, the device 100 may, for example, comprise one or more actuators for moving the at least one electrode 448, 548 (Fig. 8, 9) in a height direction z, i.e. for adjusting the distance d between the at least one electrode 448, 548 and the sample 102. The one or more actuators for adjusting the distance d between the at least one electrode 448, 548 and the sample 102 may be arranged e.g. on the electrode holder 472 (Fig. 8) or on the electrode holder 572 (Fig. 9). Additionally or instead, the one or more actuators for adjusting the distance d between the at least one electrode 448, 548 and the sample 102 may e.g. also be arranged on the sample stage 110, 410, with the result that the sample stage 110, 410 itself is movable in the z direction. By way of example, the sample stage 110, 410 (and thus also the sample 102) is first moved in the x, y and / or z direction to position the sample 102 for particle-beam-induced processing. This sets an initial distance between the at least one electrode 448, 548 and the sample 102, for example. Furthermore, by way of example, starting from the initial distance, the distance d (e.g. as an end distance) between the at least one electrode 448, 548 and the sample 102 is then adjusted either by means of the one or more actuators on the electrode holder 472, 572 or by moving the sample stage 110, 410 (further) in the z direction.

[0202] Additionally, although not shown in the figures, the device 100 may comprise, for example, one or more distance sensors for detecting the distance d between the at least one electrode 448, 548 and the sample 102. The one or more distance sensors may be arranged e.g. on the electrode holder 472 (Fig. 8) or on the electrode holder 572 (Fig. 9).

[0203] The electrodes 148, 248, 348, 448, 548 described herein may have different geometric shapes, as shown in Figures 10 to 17. Figures 10 to 17 show the respective at least one electrode (e.g. 148 in Fig. 10) and the sample 102 in a plan view - as seen from the particle beam delivery unit 114 (Fig. 1). In particular, as seen from the particle beam delivery unit 114 (Fig. 1), part of the at least one electrode covers the sample 102.

[0204] The at least one electrode 148 in Fig. 10 comprises two rectangular electrodes 148, which are arranged in edge regions of the sample 102. By way of example, Figures 3 and 4 can be regarded as a cross-section along line B-B in Fig. 10. It is noted that Fig. 3 and 4 can also be regarded as a cross-section of Fig. 11 or 14, however.

[0205] The surface 118 of the sample 102 has, for example, a used surface N and an unused surface, or an edge region, R. The at least one electrode 148 is arranged, for example, above the unused surface or the edge region R of the sample 102 as seen from the particle beam delivery unit 114. Additionally, the used surface N is not covered by the at least one electrode 148. This arrangement is particularly advantageous for electrodes that are attached to the sample stage 110 (Fig. 8).

[0206] The at least one electrode 648 in Fig. 11 comprises an electrode 648 having a square ring shape. The at least one electrode 748 in Fig. 12 comprises an electrode 748 having a rectangular shape that is arranged in a corner region of the sample 102.

[0207] The at least one electrode 848 in Fig. 13 comprises two electrodes 848, each having a rectangular shape, which are each arranged in a corner region of the sample 102. For example, the two electrodes 848 are arranged in diagonally opposite corner regions of the sample 102.

[0208] The at least one electrode 948 in Fig. 14 comprises two electrodes 948, each having a rectangular shape, which are each arranged in a side region of the sample 102. For example, the two electrodes 948 are arranged on opposite side regions of the sample 102. In contrast to Fig. 10, however, the electrodes 948 do not extend over the entire side length of the sample 102.

[0209] The at least one electrode 1048 in Fig. 15 comprises an electrode 1048 having a circular ring shape. This arrangement is particularly well suited to an electrode that is mounted on the housing 128, 528 of the particle beam dehvery unit 114. The ring shape in particular has a cutaway portion D (opening D) through which the particle beam 116 can move without hindrance. The electrode 1048 also has a rotationally symmetrical shape in relation to an undeflected beam direction of the particle beam 116.

[0210] The at least one electrode 1148 in Fig. 16 comprises an electrode 1148 having a circular ring shape with a radially cut-away ring segment F.

[0211] The at least one electrode 1248 in Fig. 17 comprises two electrodes 1248, this being produced by a circular ring shape having two radially cut-away ring segments F' opposite one another. The electrode 1248 also has a rotationally symmetrical shape in relation to an undeflected beam direction of the particle beam 116.

[0212] Fig. 18 illustrates a method for analysing and / or processing a sample 102 with a particle beam 116 using a device 100 as described above.

[0213] In a first step Si of the method, a particle beam 116 is delivered on a surface 118 of the sample 102, a charge accumulation Q appearing on the surface 118 of the sample 102.

[0214] In a second step S2 of the method, at least one electrode 148 is provided at a distance from the surface 118 of the sample 102 and / or the at least one provided electrode 148 is set to a predetermined electrical potential Ul, U2. The at least one electrode 148, together with at least one portion 150 of an electrically conductive layer 142 of the sample 102 forms at least one capacitor 152 having a predetermined capacitance C. Additionally, the predetermined capacitance C is determined on the basis of the predetermined electrical potential Ul, U2 of the at least one electrode 148 and a predetermined charge accumulation Q on the surface 118 of the sample 102 due to the delivered particle beam 116.

[0215] In a third step S3 of the method, charges on the surface 118 of the sample 102 are stored in the at least one capacitor 152.

[0216] Although the present invention has been described on the basis of exemplary embodiments, it is modifiable in diverse ways

[0217] LIST OF REFERENCE SIGNS

[0218] 100 device

[0219] 102 sample

[0220] 104 housing

[0221] 106 pump

[0222] 108 sample stage apparatus

[0223] 110 sample stage

[0224] 112 holding apparatus

[0225] 114 particle beam dehvery unit

[0226] 116 particle beam

[0227] 118 surface

[0228] 120 electron column

[0229] 122 electron source

[0230] 124 detector

[0231] 126 secondary electron

[0232] 128 housing

[0233] 130 opening

[0234] 132 underside

[0235] 134 gas dehvery unit

[0236] 136 gas pipe

[0237] 138 control unit

[0238] 140 substrate

[0239] 142 electrically conductive layer

[0240] 144 dielectric layer

[0241] 146 trajectory

[0242] 148 electrode

[0243] 150 portion

[0244] 152 capacitor

[0245] 154 potential source

[0246] 156 connection

[0247] 158 region of overlap

[0248] 160 portion

[0249] 162 dielectric

[0250] 164 processing region

[0251] 166 capacitor region

[0252] 200 arrangement

[0253] 248 electrode

[0254] 252 capacitor

[0255] 254 potential source 256 connection 348 electrode 354 potential source 356 connection 370 current measuring unit 410 sample stage (sample holder) 448 electrode 454 potential source 472 electrode holder 474 joint 528 housing 530 opening 548 electrode 572 electrode holder 648 electrode 748 electrode 848 electrode 948 electrode

[0256] 1048 electrode 1148 electrode 1248 electrode

[0257] A surface area al length a2 length

[0258] C, C capacitance d distance D(t) disturbance variable

[0259] D cutaway portion

[0260] AU1 potential difference AU2 potential difference e(t) deviation E electric field F, F' cutaway portion FB control loop G plane I current K direction N region Pl plate P2 plate

[0261] Q charge r(t) target value R region RE closed-loop control device

[0262] RS controlled system

[0263] S1-S3 method steps u(t) manipulated variable U potential U1 potential

[0264] U2 potential UM potential x direction y(t) actual value y direction direction

Claims

PATENT CLAIMS1. Device (100) for analysing and / or processing a sample (102) with a particle beam (116), the sample (102) having an electrically conductive layer (142), comprising: a particle beam dehvery unit (114) for dehvering the particle beam (116) on a surface (118) of the sample (102), at least one electrode (148), which is configured to be arranged at a distance from the surface (118) of the sample (102) and, together with at least one portion (150) of the electrically conductive layer (142) of the sample (102), to form at least one capacitor (152) having a predetermined capacitance (C), and at least one potential source (154, 254), which is electrically conductively connected to the at least one electrode (148) in order to set the at least one electrode (148) to a predetermined electrical potential (Ul, U2), wherein the predetermined capacitance (C) is determined on the basis of the predetermined electrical potential (Ul, U2) of the at least one electrode (148) and a predetermined charge accumulation (Q) on the surface (118) of the sample (102) due to the delivered particle beam (116).

2. Device according to Claim 1, wherein the at least one electrode (148) is configured to be arranged at a predetermined distance (d) from the surface (118) of the sample (102) and / or from the electrically conductive layer (142) of the sample (102), the predetermined distance (d) defines a distance of the at least one capacitor (152), the at least one electrode (148) and the electrically conductive layer (142) of the sample (102) are arranged parallel to one another and so as to overlap one another in a region of overlap (158), the region of overlap (158) defines a predetermined surface area (A) of the at least one capacitor (152), and the predetermined distance (d) and the predetermined surface area (A) of the at least one capacitor (152) define the predetermined capacitance (C) of the at least one capacitor (152).

3. Device according to Claim 1 or 2, wherein the at least one potential source (154) is configured to deliver an earth potential (UM), and the predetermined capacitance (C) is determined as a predetermined electrical potential (Ul) on the basis of the earth potential (UM).

4. Device according to Claim 1 or 2, wherein the at least one potential source (254) is configured to dehver a positive and / or negative potential (U2), and the predetermined capacitance (C) is determined as a predetermined electrical potential on the basis of the corresponding delivered positive or negative potential (U2).

5. Device according to one of Claims 1 to 4, comprising a sample holder (110, 410) for holding the sample (102), wherein the at least one electrode (148, 448) is attached to the sample holder (110, 410), and / or the sample holder (110, 410) and the at least one electrode (148, 448) are configured to be moved with one another relative to the particle beam dehvery unit (114) in order to analyse and / or process the sample (102).

6. Device according to Claim 5, wherein the at least one electrode (448) is attached to the sample holder (410) so as to be mobile, with the result that at least part of the at least one electrode (448) is able to be moved over the sample (102) as seen from the particle beam delivery unit (114) after the sample (102) has been arranged on the sample holder (410).

7. Device according to Claim 5 or 6, wherein the surface (118) of the sample (102) has a used surface (N) and an unused surface (R), and at least part of the at least one electrode (148) is configured to be arranged above the unused surface (R) of the sample (102) as seen from the particle beam dehvery unit (114), with the result that a region above the used surface (N) is free of the at least one electrode (148).

8. Device according to one of Claims 1 to 4, wherein the particle beam dehvery unit (114) has a housing (528), and the at least one electrode (548) is attached to the housing (528), and / or the at least one electrode (548) is arranged at a fixed location relative to the particle beam dehvery unit (114).

9. Device according to one of Claims 1 to 8, wherein the at least one electrode (148), as seen from the particle beam delivery unit (114), has a ring shape (1048), a circular ring shape (1048), a ring shape (1148) having at least one cutaway portion (F, F'), a rotationally symmetrical shape (1048, 1248) in relation to an undeflected beam direction of the particle beam (116), a rectangular shape (148, 748, 848, 948) and / or a square ring shape (648).

10. Device according to one of Claims 1 to 9, comprising a current measuring unit (370), the potential source (354) being electrically conductively connected to the atleast one electrode (348) via the current measuring unit (370) in order to measure a current flowing between the potential source (354) and the at least one electrode (348).

11. Device according to one of Claims 1 to 10, wherein the particle beam delivery unit (114) is configured to deliver the particle beam (116) with a predetermined particle beam current (I) for a predetermined period of time (At), and the determined charge accumulation (Q) is determined on the basis of the predetermined particle beam current (I) and the predetermined period of time (At).

12. Device according to one of Claims 1 to 11, wherein the predetermined capacitance (C) is determined in such a way that a potential difference (AU1) between the at least one electrode (148) and the at least one portion (150) of the electrically conductive layer (142) of the sample (102) is a factor of 10 lower, a factor of 100 lower, a factor of 200 lower, a factor of 300 lower, a factor of 500 lower and / or a factor of 1000 lower than an acceleration voltage (UH) of the particle beam delivery unit (114).

13. Arrangement (200), comprising a device (100) according to one of Claims 1 to 12 and a sample (102).

14. Method for analysing and / or processing a sample (102) with a particle beam (116) using a device (100) according to one of Claims 1 to 12, the sample (102) having an electrically conductive layer (142), comprising: a) delivering (Si) the particle beam (116) on a surface (118) of the sample (102), a charge accumulation (Q) appearing on the surface (118) of the sample (102), b) setting (S2) at least one electrode (148), which is arranged at a distance from the surface (118) of the sample (102), to a predetermined electrical potential (Ul, U2), the at least one electrode (148), together with at least one portion (150) of the electrically conductive layer (142) of the sample (102), forming at least one capacitor (152) having a predetermined capacitance (C), and the predetermined capacitance (C) being determined on the basis of the predetermined electrical potential (Ul, U2) of the at least one electrode (148) and a predetermined charge accumulation (Q) on the surface (118) of the sample (102) due to the delivered particle beam (116), and c) storing (S3) charges (Q) on the surface (118) of the sample (102) in the at least one capacitor (152).

15. Method according to Claim 14, comprising, before step b):determining the charge accumulation (Q) on the surface (118) of the sample (102), determining a target value for the capacitance of the at least one capacitor (152) on the basis of the determined charge accumulation (Q), and adjusting the determined capacitance of the at least one capacitor (152) for the predetermined electrical potential (Ul, U2) of the at least one electrode (148) by adjusting a distance (d) and / or a surface area (A) of the at least one capacitor (152), wherein the distance (d) of the at least one capacitor (152) is a distance of the at least one electrode (148) from the surface (118) of the sample (102) and / or from the electrically conductive layer (142) of the sample (102), and the surface area (A) of the at least one capacitor (152) is a region of overlap (158) in which the at least one electrode (148) and the electrically conductive layer (142) of the sample (102), which are arranged parallel to one another, overlap one another.

16. Method according to Claim 14, comprising, before step b): detecting an instantaneous electrical potential (y) of the sample (102), and automatically adjusting the electrical potential (U2) of the at least one electrode (254, 354), wherein a deviation (e) of the detected instantaneous electrical potential (y) of the sample (102) from a target value (r) of the electrical potential of the sample (102) is determined, a manipulated variable (u) is determined on the basis of the determined deviation (e), and the potential source (254, 354) of the at least one electrode (248, 348) is driven on the basis of the determined manipulated variable (u).

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