Improved sample damage avoidance in devices, and sample processing and repair methods.

Abstract

Avoid damage to the probe from contact with the charged sample. [Solution] A method for determining the potential of a sample includes: positioning a probe above the sample; applying first and second DC voltage offsets, each within a first range; applying an AC voltage that induces mechanical vibration of the probe; measuring first and second deviations of the probe induced with respect to the first and second DC voltage offsets; and determining the potential outside the interval from the first DC voltage offset to the second DC voltage offset, at least partially based on the first and second deviations. A method for approaching a sample includes: approaching the sample with the probe; repeatedly measuring the deviation of the probe while approaching; and confirming approach termination conditions to avoid damaging the sample, at least partially based on the deviation of the probe or its vibration frequency.

Description

[Technical Field]

[0001] This application claims priority to German Patent Application No. 102024132213.6, filed November 5, 2024, which is incorporated herein by reference to its entirety.

[0002] The present invention also relates to a method for determining the potential of a sample, a method for bringing a probe close to a sample, a method for processing a sample, and corresponding apparatus and computer programs. [Background technology]

[0003] Technical background In microelectronics, the constant increase in integration density necessitates substrates, such as lithography masks, mask blanks, or wafers, to have even better surface properties. For example, lithography masks are intended to image much smaller structural elements into the photoresist layer of a wafer. This is equally true for templates used in nanoimprint lithography. To meet these requirements, exposure wavelengths are shifting to much shorter wavelengths. The trend is toward much shorter wavelengths, extending into the extreme ultraviolet (EUV) wavelength range (10nm-15nm), and correspondingly towards EUV masks.

[0004] The constant decrease in the dimensions of structural elements frequently leads to defects in mask production. Because production is costly, defective photomasks, photolithography masks, and templates used in nanoimprint technology are repaired whenever possible.

[0005] Photomask restoration allows for the removal of portions of absorption patterns present in locations on the mask not anticipated by the design. In addition, even if the mask design anticipates absorption pattern elements, absorbing material can be deposited in locations on the mask where it was previously absent. Both types of restoration processes can generate debris fragments or particles. These debris fragments or particles can adhere to opaque, transparent, or reflective areas on the photomask and can cause imaging aberrations during lithography exposure that are visible on structured wafers.

[0006] A further problem is particles from the environment, which can adhere to the surface of the mask or other substrates, or to components of the photolithography exposure system. Furthermore, handling of the mask during the production and / or manipulation process can generate particles that can adhere to the mask.

[0007] Two additional challenges exist for photolithography exposure systems operating with electromagnetic radiation in the EUV wavelength range. Firstly, for EUV masks, there is currently no satisfactory protection (e.g., a pellicle) for the surface supporting the structural elements. As a result, EUV masks tend to accumulate particles, particularly on this structured surface. Secondly, EUV radiation sources generally use tin plasma to generate EUV radiation. Particles from the high-temperature plasma can deposit on the components of the EUV exposure system, particularly on its optical components or elements, including the EUV mask, and impair their function.

[0008] The decreasing structural dimensions of photolithography masks are increasing the difficulty of the cleaning process. Furthermore, as exposure wavelengths decrease, increasingly smaller foreign particles or dust particles adhering to the mask of the exposure system or to the surface of the optical elements are becoming visible on the wafer during the exposure process.

[0009] Given the increasingly smaller structures, situation-specific solutions are becoming increasingly important for the processing and cleaning of masks—and more generally, substrates. In particular, it may be necessary to remove various defects on the same substrate with an acceptable level of cost and inconvenience. Surface processing, especially particle migration and the lifting / removal of individual particles from the surface, is generally a difficult and time-consuming process. External constraints may limit the available tools and processing operations. Furthermore, completely removing particles adhering to a substrate can be costly and inconvenient.

[0010] Generally, processing a sample requires bringing the probe close to the sample, but this is not always possible without problems for the following reasons.

[0011] During the process of loading a sample into a vacuum, for example, the vacuum evacuation and measurement processes can charge the sample. Similarly, during the process of inspecting a sample (e.g., a photomask) in a scanning electron microscope (SEM), the sample can be charged by electrons introduced by the primary beam and by secondary electrons (SE). This charging behavior here mainly depends on the SE yield (SEY). Samples with large conductive structures that do not or cannot be electrically contacted are critical in both cases. These samples include, for example, so-called "chromium on glass blanks" for particle monitoring tests and EUV masks. EUV masks, as high-end masks, are particularly expensive and, due to their small size, are especially sensitive to particle contamination and electrostatic discharge (ESD).

[0012] For example, if a probe (e.g., an AFM (atomic force microscope) tip) comes into contact with or is guided near a charged sample, the sample may discharge through the tip (in the form of a so-called ESD event), which can damage both the sample and the probe.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0014] Therefore, the present invention is based at least in part on the purpose of improving the corresponding methods, apparatuses, and computer programs.

Means for Solving the Problems

[0015] This object is at least partly achieved by the aspects described herein.

[0016] The first aspect of the present invention relates to a method for determining a potential related to a sample, the method comprising: positioning a probe above the sample; applying at least first and second DC (direct current) voltage offsets each within a first range; applying an AC (alternating current) voltage to the probe for the purpose of inducing mechanical vibration of the probe; measuring a first displacement of the probe induced with respect to the first voltage offset and a second displacement induced with respect to the second voltage offset; and determining a potential (also referred to herein as the sample potential or the potential of the sample) outside the interval ranging from the first DC voltage offset to the second DC voltage offset based at least in part on the first and second displacements.

[0017] The inventor has recognized that the situation of the present invention is suitable for utilizing the following physical relationship: There exists an electric force of the following formula acting between two objects having a finite potential difference ΔV spaced apart from each other in the z direction, and the capacitance C ~ (about) z -1 is as follows.

Number

Number

[0018] When a DC voltage offset V DC is applied so that the potential difference ΔV disappears, the acting electric force F el does not exist.

[0019] The DC voltage offset V DC and the time-varying AC voltage V AC When applied, this generally produces a force given by the following equation that varies with time:

Number

[0020] The two objects described above can be, for example, a sample and a probe in this specification. ​​​​​​​​​​​mod The applied AC voltage 131 cannot induce a strong force 141 between the probe and the sample. On the contrary, the latter tends towards zero. Furthermore, due to the zero crossing (and the resulting sign change) in the applied voltage 131, the frequency of the induced force (which has an amplitude that tends towards zero) is 2 × f mod This has the effect that, since this frequency is far from the probe's resonant frequency, it is not possible to excite the probe and make it vibrate there (or it is only possible to excite it with great difficulty), and this further contributes to bringing the amplitude of the force and the amplitude of the vibration closer to zero.

[0022] (V DC -V CPD ) 2 For different DC voltage offsets 122 such that the offset is >0, for example, a higher DC voltage offset 122, an applied AC voltage 132 (for example, having the same or different amplitudes and / or frequencies) will result in a relatively larger deviation or amplitude of the induced oscillation 142. This is evident from the fact that a parabola has a slope that is not equal to zero at all points away from its vertex.

[0023] Previously known methods could only determine the sample potential within a voltage range to which a voltage could also be applied. Therefore, if it is desired to measure / determine the sample potential, such as the mask voltage, within the technically relevant range of -63V to +63V using these conventional methods, this requires a "sweep" from, for example, -75V to +75V (at least from -63V to +63V in any case). This requires applying a DC voltage offset and / or systematically varying the DC voltage offset over a predetermined range, for example, continuously or in discrete steps, as will be described in more detail herein. This presents problems in three respects: firstly, such a wide DC voltage offset range necessitates additional amplifiers for higher voltages and a suitable mixer. This complicates the above methods and their corresponding apparatus, increases costs, and makes the methods more susceptible to interference. Secondly, typical controllers exhibit dielectric breakdown strength only up to 42V, meaning that if a short circuit is present, this can cause (irreparable) damage to probes, samples, equipment, etc. Thirdly, voltages above 50V are outside the ultra-low voltage range, which is a safety concern and requires additional assurance. The latter can be addressed by the steps described herein, which allow for the determination of potentials outside the interval from the first DC voltage offset to the second DC voltage offset, thereby simplifying, making safer, accelerating, and reducing the cost of the above method.

[0024] The tests have shown that the method according to the present invention can adequately cover a DC voltage offset range of -200V to +200V, and that errors of less than -10% are obtained during the process.

[0025] As a result, the shortcomings of conventional methods can be addressed with respect to the following issues: Firstly, the sample potential is often not accurately known, and therefore a larger, more accessible measurement range can be useful. Secondly, if the potential difference between the sample and the probe is too large, both the probe and the sample can be damaged (often irreparably). In particular, with expensive samples such as EUV masks, even a very small voltage difference (~20V) that may result from sample loading, for example, is sufficient to cause irreparable damage. Such voltage differences can be determined with high reliability.

[0026] In one preferred example, a first DC voltage offset can be applied at a first time point, and a second DC voltage offset can be applied at a second time point (different from the first time point) (for example, before or after the first time point in time). Applying at least the first and second DC voltage offsets may include a "sweep".

[0027] The applied voltage diversifies / changes during the so-called "sweep." The applied voltage can generally change from a minimum to a maximum value (or vice versa) in continuous or discrete (e.g., equally spaced) steps at predetermined intervals and / or intervals determined by the user or device. As a result, multiple voltages (in this specification, e.g., DC voltage offsets) are applied sequentially over time during or in the "sweep." The so-called "sweep" can proceed, for example, in relation to the application of first and second DC voltage offsets: in one example, the first DC voltage offset corresponds to the minimum value of the sweep interval, and the second DC voltage offset corresponds to the maximum value of the sweep interval. As described herein, the first DC voltage offset can be applied at a first time point, and the second DC voltage offset can be applied at a second time point (different from the first time point) (e.g., before or after the first time point). The applied voltage can be swept during the time between the first and second time points; in other words, the applied voltage can change from the first DC voltage offset to the second DC voltage offset (or vice versa) in continuous or discrete steps.

[0028] The application of AC voltage is performed temporarily, for example, during the periods of the first and second time points. In this relationship, for example, the first DC voltage offset and AC voltage can be applied at the first time point, and the second DC voltage offset and AC voltage can be applied at the second time point.

[0029] In one preferred example, the deviation may include the amplitude and / or phase of a mechanical vibration.

[0030] The inventors recognized that the amplitude and phase of vibrations are particularly well-suited for performing a process that determines the potential with high precision and reliability.

[0031] For example, the first and second deviations may include in-phase and / or orthogonal components.

[0032] The use of in-phase and / or orthogonal components can further simplify or make the above method more efficient. For example, instead of analyzing the demodulated amplitude signal, one can analyze (e.g., by fitting (fitting to a function, approximating with a mathematical formula)) the in-phase and / or orthogonal components, each of which can exhibit a very good linear profile. This can greatly simplify and accelerate the subsequent analysis steps and / or greatly increase their accuracy and / or reliability.

[0033] In one example, measuring the first and second deviations may include lock-in amplification.

[0034] Indeed, this can be particularly advantageous in combination with the use of in-phase and / or orthogonal components as described herein, since in-phase and / or orthogonal components can be directly provided by conventional lock-in amplifiers.

[0035] In principle, lock-in amplifiers are advantageous for measuring weak signals that may be buried in strong background noise. A lock-in amplifier is configured to extract this signal, for example, by mixing the signal with a reference frequency and analyzing the resulting components. These components may be, or may include, the in-phase component (also designated "X" herein) and orthogonal component (also designated "Y" herein) as described herein.

[0036] For example, the frequency of the AC voltage can be made approximately equal to a multiple of the probe's resonant frequency.

[0037] Indeed, resonant excitation is particularly suitable because it can achieve high amplitudes, and therefore, large differences in displacement can be observed even when small differences in DC voltage offset exist. This simplifies and accelerates the above method, making it more accurate.

[0038] In one preferred example, the above first range can extend from -10V to +10V.

[0039] Given the problems of conventional potential measurement methods described herein, the range of -10V to +10V is particularly advantageous: instead of extending the sweep range to be able to examine the maximum possible voltage range, the present invention can include a DC voltage offset that varies within the (relatively small) range of -10V to +10V, which corresponds to the typical output range of the controller used for the corresponding device.

[0040] For example, determining the potential may involve fitting a first data point containing at least a first deviation and a first DC voltage offset, and a second data point containing a second deviation and a second DC voltage offset, using a fitting function.

[0041] The above method may include, for example, a step of fitting data points (e.g., 10 or more, 100 or more, etc.). The inventors have found that a suitable compromise between the accuracy and speed of the above method can be found, for example, within the range of 10 to 300 data points. In this relationship, determining the sample potential by the method described herein can be performed particularly robustly, with high reliability and speed.

[0042] In one preferred example, determining the potential may further include extrapolating and / or identifying points where the fit function is zero.

[0043] The key feature here is that it enables not only good interpolation but also extrapolation, and therefore, for example, the intersection point of a fitted function (e.g., a straight line) outside the first range (e.g., -10V to +10V) can be determined. Where this function intersects the horizontal axis, the minimum value of the deviation can be determined, and this value can be used to determine the sample potential. The inventors recognized that this fitting enables remarkably accurate potential measurements even for extrapolation far outside the first range.

[0044] As an example, the fitting function may include a linear (first-order) function, and preferably, at least in part, it may include a linear function correction based on the probe's resonant frequency, the vibration quality factor (Q value), and / or the spring constant.

[0045] In initial tests, calculations, and simulations, the inventors recognized that, particularly for distances less than 10 μm between the probe and the sample, the resonant frequency changes significantly during the change / application of the DC voltage offset (also referred to as "sweeping"), and therefore, the applied AC voltage corresponds to non-resonant excitation. As a result, the measured signal (e.g., the deviation as a function of the applied DC voltage offset) can include signals that are considerably close to linear or nonlinear signals. Therefore, in the nonlinear case, it may be advantageous to include a linear function correction in the fit function, or to use a nonlinear fit function. Thus, in one preferred example, the fit function can be based, at least in part, on the distance between the sample and the probe.

[0046] In one preferred example, the positioning can be performed such that the distance between the probe and the sample can be 0.001 μm to 1000 μm, preferably 50 μm to 150 μm. In some examples, a minimum distance of 0.01 μm, 0.1 μm, 1 μm, or 10 μm can also be provided.

[0047] As described herein, the above method has been found to be able to be carried out efficiently within these ranges: on the one hand, the distance between the sample and the probe is small enough to satisfy the conditions prepared for, for example—as described herein—a linear relationship between the deviation and the DC voltage offset, or for a reasonable estimation of the correction of a linear function (including outside the first range), and / or the force between the sample and the probe is strong enough to carry out the above method with high reliability. On the other hand, the sample and the probe are spaced far enough apart from each other that collisions between the sample and the probe can be eliminated or avoided with a high probability. As described herein, possible nonlinearities can occur, and such nonlinearities are generally more noticeably apparent outside the first range. However, these nonlinearities can be incorporated in exactly the same way into the method described herein by taking them into consideration computationally.

[0048] A second aspect of the present invention relates to a method for bringing a probe close to a sample, the method comprising: bringing the probe close to the sample; repeatedly measuring the deviation of the probe during the approach process; and determining an approach termination condition to avoid damaging the probe, at least partially based on the deviation of the probe.

[0049] The detection of excessively high mask potentials, achieved by the first embodiment, is indeed helpful in avoiding sample damage, but it is not necessarily sufficient to allow for the repair of the sample in subsequent steps, as the actual goal is the ability to repair the sample. Conventional methods, for example, assume that the latter (surface) is uniformly discharged after a discharge, whereas the inventors recognized that local charges may still exist on the sample even after such a discharge, and as a result, the sample and probe cannot be safely brought close to each other. The inventors recognized that these local charges can still be high enough to cause a considerable amount of damage to the sample and / or probe. This fact is exacerbated because most methods for measuring sample potential involve large-area measurements, which generally produce an average value over the entire area, and this large area is very large compared to the area that the probe deals with (e.g., the same as the cross-sectional area of ​​the probe tip). Such average values ​​do not contain any information about possible local charges. However, when the probe is brought close to the sample, and even when it comes into contact with the sample, damage to the sample and / or the probe generally occurs precisely at or near these localized charges, even in the case of the large-area discharge of the sample mentioned above. However, even if such cases do not generally occur, it is highly desirable to be able to identify and avoid these cases at an early stage, especially in the case of very expensive samples such as EUV masks.

[0050] As an example, the above verification can be performed by a real-time device configured to verify the above approach termination condition in 2ms or less, preferably 1ms or less, and particularly preferably 0.5ms or less.

[0051] Such rapid confirmation of approach termination conditions can ensure that unwanted collisions can be avoided, even at relatively high approach speeds that enable rapid processing.

[0052] The above method may further include, for example, a step of terminating, at least partially, the process of bringing the probe closer to the sample based on confirming the conditions for termination of approach.

[0053] Defining proximity termination conditions can provide a basis for objective judgment, making the above method safer and equally reliable, regardless of the user. Checking proximity termination conditions can be done automatically, for example, which simplifies the user's work, accelerates the above method, and makes it more reliable and safer.

[0054] In a preferred example, the above termination can be performed within 2 ms, preferably within 1 ms, and particularly preferably within 0.5 ms, after the occurrence of the approach termination condition.

[0055] Such rapid termination of approach can ensure that unwanted collisions can be avoided, even at relatively high approach speeds that allow for rapid handling.

[0056] The process of bringing the probe closer can be carried out at a speed of, for example, 0.1 μm / s or more, more preferably 1 μm / s or more, and particularly preferably 2 μm / s or more.

[0057] This reduces the processing time required for the sample, and therefore saves time and costs.

[0058] In one preferred example, the above approach termination condition may include the probe overshooting (going too far) a predetermined deviation.

[0059] The inventors have found that for sufficiently large distances between the probe and the sample, the deviation (e.g., measured using a photodiode and a light beam reflected by the probe, as described herein, e.g., amplitude of vibration, bending of a portion of the probe) remains within a predetermined range. As a result, overshooting a predetermined deviation constitutes a particularly reliable approach termination condition, which can apply to both static procedures (without probe-induced vibrations) and dynamic procedures (with probe-induced vibrations).

[0060] The above method may further include, for example, the step of measuring the resonant frequency of the probe during the approach process.

[0061] In one preferred example, the approach termination condition described above may include overshooting (going too far) a predetermined frequency shift of the resonant frequency.

[0062] The inventor recognized that the shift to lower (higher) frequencies occurs in conjunction with attractive (repulsive) forces, and that this is what the inventor is taking advantage of. It is remarkable that this procedural means is extremely sensitive, and therefore, approach termination can be achieved quite quickly based on this.

[0063] For example, the approach termination condition may include the resonant frequency undershooting (falling below) a predetermined minimum frequency.

[0064] The electrostatic force resulting from the potential difference between the sample and the probe is an attractive force, and therefore a shift to a lower frequency. As a result, a minimum frequency can be defined, and the undershoot of this minimum frequency can serve as a termination condition, which is particularly simple and highly reliable.

[0065] A third aspect of the present invention relates to a method for processing a sample, the method comprising: a step of a method for determining the potential as described herein; and a step of bringing a probe close to the sample.

[0066] The combination of a method for determining the potential and a method for approaching the sample with a probe offers advantages in several different respects: Firstly, it ensures that the approach is only performed from the outset if the potential determination indicates that it can be carried out safely with a high probability. Secondly, the probe intended for later approach is used for potential determination, which is a particularly efficient procedure for saving material, time, and cost.

[0067] For example, the method described herein may further include, at least in part, the step of discharging the sample at least partially based on the determination of the potential.

[0068] This discharge may include, for example, the discharge described in German Patent Application Publication No. 102013212957 (Patent Document 1).

[0069] For example, discharge can be performed at a potential of ±1V or higher, preferably ±5V or higher, and particularly preferably ±10V or higher.

[0070] In this case, "greater than or equal to" should be understood as referring to the absolute value of the potential. Therefore, a potential of ±1V or more corresponds, for example, to a potential of -1V or less or +1V or more. Thus, it can be ensured that a discharge occurs whenever the potential is too high for a subsequent step of the method—for example, the step of bringing the probe closer to the sample.

[0071] In one preferred example, the step of bringing the probe closer to the sample in the above method can be performed only for potentials less than ±20V, preferably less than ±15V, and particularly preferably less than ±10V.

[0072] In this way, it is possible to ensure that the probe can be brought close to the sample safely with a relatively high probability.

[0073] The sample can be charged at least partially. This can be achieved, for example, by treating the sample with a particle beam (e.g., an ion and / or electron beam) and / or by observing the sample (e.g., using a transmission electron microscope and / or a scanning electron microscope).

[0074] For example, the probe may include a probe for a scanning probe microscope, and the probe may comprise a probe arm and / or a measuring tip, and / or the deviation may be measured by a light beam reflected by the probe.

[0075] In particular, the use of probes (e.g., probes in scanning probe microscopes) in displacement measurements using reflected light beams offers numerous technical advantages: Measuring the displacement of the probe arm allows for extremely precise capture of the surface structure of a sample. This results in very high spatial resolution, which can extend to the atomic level. The method is extremely sensitive to small forces and displacements. This makes it possible to detect very fine topographic (surface roughness) and mechanical properties of a sample. Scanning probe microscopes can be operated in various modes, such as contact mode, tapping mode, and / or non-contact mode, depending on the specific requirements of the inspection. This makes scanning probe microscopes usable in a variety of ways for a wide variety of samples and applications. Measuring the displacement of the probe arm generally does not cause any physical changes to the sample, so sensitive or valuable materials can be inspected without damage. In addition to topographic imaging, scanning probe microscopes can also measure other physical properties of a sample, such as electrical, magnetic, or mechanical properties, by using the corresponding probes and measurement methods. The deviation of the probe arm can be measured and analyzed in real time, which allows for immediate feedback on the properties of the sample and facilitates the adaptation of measurement parameters during the experiment.

[0076] The sample may include, for example, an object for lithography, and preferably includes a lithography mask. The sample may be a photolithography mask. The sample or photolithography mask may have an aspect ratio of 1:1 to 1:4, preferably 1:1 to 1:2, and particularly preferably 1:1 or 1:2. The sample or photolithography mask may have a substantially rectangular shape. The sample or photolithography mask may preferably have a length and width of 5 to 7 inches (12.7 cm to 17.8 cm), and particularly preferably 6 inches (15.2 cm). Alternatively, the sample or photolithography mask may have a length of 5 to 7 inches and a width of 14 inches (35.6 cm), preferably 6 inches and 12 inches (30.5 cm).

[0077] The use of such probes is particularly advantageous in relation to these lithographic objects, because the aforementioned advantages are extremely relevant when handling the corresponding sample—especially when handling the sample gently without damaging it.

[0078] A fourth aspect of the present invention relates to an apparatus for processing a sample. This apparatus comprises one or more means configured to automatically perform one or more steps of one or more methods described herein.

[0079] This automation enables the consistent and iterative execution of the methods described herein. This reduces human error and ensures high accuracy and reproducibility of results, which is particularly important in quality control and scientific investigations. In addition, this automation enables the execution of complex and time-consuming processes, such as the methods described herein, more quickly and efficiently. This results in a significant reduction in processing time, enabling higher processing speeds, which can reduce costs. Automated systems reduce the need for manual intervention and thus minimize variability that may arise due to different operators. This results in uniform and high-quality results, reduces the risk of operational errors, and increases the reliability and safety of the methods described above.

[0080] The embodiments described herein can be used in various examples.

[0081] The sample referred to in this application can include, for example, a wide variety of substrates, such as semiconductor substrates used in the semiconductor industry. In some examples, the sample can include objects for lithography.

[0082] The samples referenced herein may further include reticles (including various forms such as 6x6 inches, 6x12 inches, and 12x12 inches, with or without pellicles), such as nano-imprint lithography (NIL) templates or stamps used for nanoscale pattern replication.

[0083] In addition, or instead, the embodiments described herein can be used in samples such as wafers. These wafers can be supplied in various sizes and / or cuts. These wafers may include, for example, Si, SiO, sapphire, SiC, GaN, InP, Ge, GaAs, AlGaAs, ZnO, or CdS. These samples may further include wafers containing unique or heterogeneous structures for each chip, wafers having both structured and unstructured regions, partially processed or pre-processed wafers that have undergone one or more manufacturing steps, and / or die-cut (diced) wafers (e.g., mounted on a frame such as a 380 mm frame). Additional applicable substrate types include, for example, package substrates used in semiconductor packaging processes, dies, interposers, circuit boards, substrates to which circuit editor applications are applied, photonic integrated circuits, and hybrid electro-optical circuit boards that combine electronic and optical functions. The methods and apparatus described herein are applicable, for example, to microfluidic systems including lab-on-a-chip devices, metamaterial substrates (which can be characterized by engineering properties, such as a negative refractive index), and advanced nanomaterials, such as two-dimensional materials, nanosheets, or topological insulators. In some possible examples, the sample can be a sample for quantum computing applications (e.g., a chip with one or more qubits or other quantum information processing elements), or a sample for artificial intelligence and machine learning applications employing a dedicated electronic circuit architecture.

[0084] An additional aspect of the present invention relates to a computer program, which includes instructions for performing at least one step of the method described herein. The computer program can be written in any form of programming language, and these forms may include components, subroutines, or other entities suitable for use in a computer environment, either as a standalone program or as a module.

[0085] The preferred examples of the invention described herein, and the features and characteristics optionally described herein, should also be understood as being disclosed in combination with others. In particular, the description of a feature included in a preferred example—unless there is an explicit description to the contrary—should not be interpreted in the present invention as meaning that the feature is essential or indispensable to the function of that preferred example. Similarly, features described herein with respect to steps of a method can be implemented as instructions in a computer program and as means of a device, and vice versa. [Brief explanation of the drawing]

[0086] [Figure 1] Figure 1a schematically shows the harmonic approximation of the force induced by the applied AC voltage as a function of the DC voltage offset. Figure 1b schematically shows the probe and the sample, as well as the vibration of the probe induced in relation to the sample. [Figure 2] This diagram schematically shows the deviations, specifically the amplitude, common-mode component, quadrature component, and phase, as functions of the applied DC voltage. [Figure 3] Figure 3a is a schematic diagram showing the components of an exemplary apparatus that can be used for control and sample potential determination. Figure 3b shows an exemplary probe and how this probe can be connected to the components in Figure 3a. [Figure 4] This figure illustrates an illustrative comparison of two scenarios in which probes to which AC voltage is applied at different distances from the sample have different resonant frequencies. [Figure 5] This figure shows an illustrative flowchart of a preferred method according to the present invention. [Modes for carrying out the invention]

[0087] Detailed description of preferred embodiments Figure 1b also shows the probe 150 and the sample 160, as well as vibrations 170 induced by the probe 150 on the sample 160. The probe 150 can be, for example, part of an apparatus for processing the sample 160. In this case, the probe has a probe arm 151, one end of which can be fixed to a moving stage (also referred to herein as "stage"). The moving stage or stage can be configured, for example, to move the probe 150 in the x, y, and / or z directions, and / or to rotate the probe 150 along one or more angles. The moving stage can be, for example, a 6DOF (degree of freedom) moving stage, i.e., a moving stage with six degrees of freedom. In the example in Figure 1b, a measuring tip 152 having a tip endpoint 153 is located at the other end of the probe arm 151. For example, first and second DC voltage offsets described herein can be applied between the probe 150 and the sample 160. The measuring tip 152, having a tip endpoint 153, can undergo mechanical vibrations (in a greatly enlarged form) represented by the dashed double arrow 170, as illustrated in the example in Figure 1b, by the periodic bending or vertical vibration of the probe arm 151. As a result, the distance between the measuring tip 152 or tip endpoint 153 and the sample 160 changes proportionally and periodically. This corresponds to the first and / or second displacements described herein.

[0088] Figure 2 schematically shows the deviation, specifically the amplitude 210, the in-phase component (X) 212, the orthogonal component (Y) 211, and the phase 230, as a function of the applied DC voltage offset (U).

[0089] A lock-in amplifier is a device used to measure a signal buried in a highly noisy environment. The lock-in amplifier isolates this signal from the noise using phase detection. The common-mode component 212 and the quadrature component 211 are two essential parts of this process.

[0090] The in-phase component (X component) 212 is the projection of the input signal onto the reference signal wave and is in phase with the input signal. The in-phase component represents the portion of the signal that directly coincides with the reference phase. The in-phase component is mathematically obtained by multiplying the input signal by a sinusoidal reference signal and then applying a low-pass filter. This component can provide information about the amplitude that is in phase with the reference in the signal. The quadrature component (Y component) 211 is the projection of the input signal onto a reference signal wave that is phase-shifted by 90 degrees (i.e., orthogonal to the reference phase). The quadrature component represents the portion of the signal that is phase-shifted by 90 degrees with respect to the reference phase. The quadrature component is mathematically obtained by multiplying the input signal by a cosine reference signal and then applying a low-pass filter. This component can provide information about the amplitude that is orthogonal to the reference in the signal.

[0091] In this case, the theoretical profile corresponding to amplitude 210 shows a V-shaped profile, and the orthogonal component (Y component) 211 and the in-phase component (X component) 212 each show linear profiles, all of which have the same zero crossing or zero point, which theoretically corresponds to the sample potential. As a result, the amplitude 210, the orthogonal component (Y component) 211, and / or the in-phase component (X component) 212 can be fitted with the corresponding function to determine the zero (for example, for amplitude 210) or the zero crossing (for example, for the orthogonal component (Y component) 211 and / or the in-phase component (X component) 212), i.e., the sample potential.

[0092] The phase has a 180° jump at the sample potential. By fitting the phase with the corresponding function, the zero crossing, i.e., the sample potential, can be determined.

[0093] In the example in Figure 2, the first range 221 is the range encompassing measurement point 220. The exemplary DC voltage offsets include first, second, and additional DC voltage offsets within the first range 220. In the example in Figure 2, only the measurement points for the common-mode component (X component) 212 are shown, and the dashed lines indicate the fitting of these measurement points 220. Extrapolation allows for the determination of a mask potential that is zero, i.e., outside the interval (first range) across the multiple DC voltage offsets. In this case, the first range can be, for example, within the interval of -10V to +10V, and the determined mask potential can be, for example, an absolute voltage value higher than 10V.

[0094] Figure 3a shows schematic diagrams of components 310, 320, 331, and 332 of an exemplary apparatus 300 that can be used for control and sample potential measurement.

[0095] In this case, the exemplary apparatus 300 in Figure 3a comprises a computer 310. In some implementations, the apparatus 300 and / or the computer may comprise a data processor and a storage medium. The data processor may be configured, for example, to perform steps of the method described herein and / or to provide mechanical and / or electronic components related to instructions for performing these steps. The storage medium may store data, information, software 313, protocols 311, etc., described herein, for performing the method described herein. As an interface for this, for example, a COM server 314 may be provided. The COM server (component object model server) 314 may comprise, for example, a software component based on COM technology and may provide services or functions for other applications. This component may communicate with additional apparatus 320 (for example, a controller for the mechanical and / or electronic components described above) by, for example, IP (Internet protocol) and / or TCP (transmission control protocol) protocols. In some implementations, the device 300 may comprise one or more computers 310, each containing one or more data processors, which are configured to execute one or more programs containing a variety of instructions based on the principles described above. Each data processor may contain one or more processor cores, each processor core may contain logic circuits for data processing. For example, a data processor may comprise an arithmetic logic unit (ALU), a control unit, and various registers. Each data processor may include cache memory. Each data processor may comprise a system-on-chip (SoC), which may include multiple processor cores, random access memory (RAM), a graphics processor, one or more controllers, and one or more communication modules.Each data processor can contain millions or even billions of transistors.

[0096] The controller 320, comprising, for example, one or more field-programmable gate arrays (FPGAs) 321, 322, and / or an operating system 323 specific to the controller, can, in this example of the present invention, control, for example, a photodiode 331 and / or a stage 332, and / or receive data recorded by them (e.g., deviations detected by the photodiode 331). The recorded data can then be provided to a computer 310, for example, via an IP / TCP interface.

[0097] The methods described herein can be performed by one or more computers 310, each computer 310 comprising one or more data processors for data processing, one or more storage media for data storage, and / or one or more computer programs including instructions, which, when executed by one or more computers, cause the above process to be performed. One or more computers may be equipped with one or more input devices, such as a keyboard, mouse, touchpad, and / or voice command module, and one or more output devices, such as a display and / or speaker. Accordingly, a graphical user interface 312 may be provided, through which a user can start, stop, pause, and / or at least partially control or influence the execution of the methods described herein.

[0098] In some implementations, one or more computer devices may comprise digital electronic circuits, computer hardware, firmware, software, or a combination of the above elements. Feature functions for data processing can be implemented within a computer program product, which is substantially embodied in the form of an information carrier, for example, in the form of a machine-readable storage medium, for execution by a programmable processor; the steps of the method can be performed by a programmable processor executing program instructions to fulfill the functions of the described implementation. Alternatively, program instructions can be encoded in a propagating signal, which is an artificially generated signal, such as an electrical, optical, or electromagnetic signal generated by a machine, for the purpose of encoding information for transmission to a suitable receiving device for execution by a programmable processor.

[0099] For example, one or more computers can be configured to run computer programs, and these computers may have general-purpose and dedicated microprocessors, and any desired processor of any kind of digital computer. Generally, processors receive instructions and data from read-only memory, random-access memory, or both. The elements of a computer system include one or more processors for executing instructions, and one or more storage devices for storing instructions and data. Generally, a computer system also has, or is operationally coupled to, storage devices such as hard disks, magnetic disks, semiconductor drives, magneto-optical disks, or optical disks for receiving data from or transmitting data to one or more machine-readable storage media, or both. Machine-readable storage media suitable for realizing computer program instructions and data include various forms of non-volatile memory, which include, for example, semiconductor memory devices such as EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable ROM), flash memory devices, and semiconductor drives; magnetic disks such as internal hard disks or removable disks; optical disks; and CD-ROM (compact disc ROM), DVD-ROM (digital versatile disc ROM), and / or Blu-ray discs.

[0100] In some implementations, the processes described above can be executed using one or more mobile computer devices, one or more local computer devices, and / or one or more remote computer devices (which may be, for example, cloud computer devices). For example, the software method forms one or more computer programs which are executed on one or more programmed or programmable computer systems, either on mobile computer devices or local computer devices (which may include various architectures such as distributed systems, client / server systems, grid systems, or cloud systems), each comprising at least one processor, at least one data storage system (including volatile and non-volatile memory devices and / or memory elements), at least one wired or wireless input device or port, and at least one wired or wireless output device or port.

[0101] In some implementations, software can be provided on a medium such as a CD-ROM, DVD-ROM, Blu-ray disc, semiconductor drive, or hard disk, which can be read by a general-purpose or dedicated programmable computer, or the software can be transmitted over a network (in a form encoded in a propagating signal) to a computer on which the software is executed. The above functions can be executed on a dedicated computer or using dedicated hardware such as a coprocessor. The software can be implemented in a distributed manner, in which different parts of the computation specified by the software are executed by different computers. Preferably, any such computer program is stored on or downloaded onto a storage medium or memory device (e.g., a semiconductor memory device or storage medium or optical medium), which can be read by a general-purpose or dedicated programmable computer, and when read by a computer system, can set up and operate the computer system, thereby enabling the methods described herein to be executed. The system according to the present invention can also be considered as a computer-readable storage medium composed of computer programs, which thus causes a computer system to perform the functions described herein in a specific or predetermined manner.

[0102] Figure 3b shows an exemplary probe 350 for an apparatus that processes, for example, a sample 360, and how this probe can be connected to components 331 and 332 in Figure 3a. In the example in Figure 3b, the probe is positioned above the sample 360 ​​by, for example, a stage 332, essentially as in Figure 1b. The light source 340 is configured to direct a light beam to the probe, for example, the upper surface of a reflective probe arm, so that, for example, the reflected signal can be recorded by a photodiode 331 and transmitted to a controller 320.

[0103] The photodiode 331 can be, for example, a four-quadrant (four-segment) photodiode (4Q (four quadrant) photodiode) and / or can play an important role in measuring the displacement of a probe arm (for example, in an atomic force microscope (AFM)): as described herein, the probe arm can reflect a light beam or laser beam so that this beam strikes the surface of a four-quadrant photodiode. This photodiode can be subdivided into four distinct regions (quadrants), each of which can capture a portion of the reflected laser beam. These quadrants are generally designated A, B, C, and D. If the probe arm is displaced due to interaction with the sample surface, the position of the reflected laser beam changes on the photodiode. This change produces different intensities of light (for each quadrant) striking the individual quadrants. The photodiode can, for example, generate an electrical signal proportional to the light intensity in each quadrant. By comparing signals from different quadrants, the deviation of the probe arm can be calculated in two dimensions (vertical and horizontal): the difference between the signals in the upper quadrant (A+B) and the lower quadrant (C+D) indicates the vertical deviation of the probe arm. The difference between the signals in the left quadrant (A+C) and the right quadrant (B+D) indicates the horizontal deviation of the probe arm.

[0104] Figure 4 shows an illustrative comparison of two scenarios in which probe 450 has different resonant frequencies when an AC voltage is applied at different distances 454 and 454' from the sample. These scenarios occur, for example, in the method of moving probe 450 towards sample 460 as described herein.

[0105] In the upper region 410 of Figure 4, the probe 450 is located at a first (large) distance 454 from the sample. The profile 411 of the amplitude of the induced vibration as a function of frequency is shown to the right. In this example, the frequency with the highest amplitude is approximately 300,000 Hz.

[0106] In the lower region 420 of Figure 4, for example, the probe 450 is at a second (small) distance 454' from the sample after or during the process of bringing the probe 450 closer to the sample 460. The profile 421 of the amplitude of the induced vibration as a function of frequency is shown to the right. In this example, the frequency with the highest amplitude is approximately 299,999 Hz, and is therefore redshifted (shifted towards longer wavelengths) compared to the case shown in the upper region 410.

[0107] Therefore, Figure 4 schematically shows how frequency shifts can occur as a function of the distances 454 and 454' between the probe 450 and the sample.

[0108] Figure 5 shows an illustrative flowchart of a preferred method according to the present invention, which combines several embodiments described herein.

[0109] The method in Figure 5 can be further divided into the following three aspects: a method 510 for measuring the potential related to the sample, a method 520 for discharging the sample, and a method 530 for bringing the probe closer to the sample.

[0110] Method 510 for measuring potential related to a sample comprises the following steps 511-515: This method can be initiated by step 511, which involves positioning the probe above the sample. Subsequently, at least first and second DC voltage offsets are applied, each within a first range (step 512). As described herein, the first DC voltage offset may be applied at a first time point, and the second DC voltage offset may be applied at a second time point (different from the first time point) (e.g., before or after the first time point in time). Furthermore, method 512 includes step 513, which involves applying an AC voltage to the probe for the purpose of inducing mechanical vibration of the probe, and step 514, which involves measuring a first deviation of the probe induced with respect to the first DC voltage offset and a second deviation of the probe induced with respect to the second DC voltage offset. Based on this, the potential outside the interval from the first DC voltage offset to the second DC voltage offset can be determined at least partially based on the first and second deviations (step 515). The potential P thus measured is within the range "P min <P<P max Based on whether or not it is inside the box, the probe can then continue approaching the sample (step 531), or the sample can be discharged (step 520). In this case, P min This can correspond to the lower threshold, P max This can correspond to the higher threshold, and the range P min <P<P max (i.e., the lower threshold P) min The higher of the two thresholds P. max Assuming a potential P (of the sample) below a certain value, it can be assumed that safe access is possible. For example, P min It can be -1V, -5V, -10V or -20V, and / or P max This can be 1V, 5V, 10V, or 20V. In other examples, P min and / or P max Other predetermined values ​​can also be used.

[0111] The sample potential is too high to allow the probe to approach safely (i.e., [P min , P max If there is a potential outside of [P], a decision can be made to discharge the sample: In the example of Figure 5, method 520 for discharging the sample includes simply discharging the sample (e.g., by known methods and / or methods described herein). In particular, the discharge can be based on the measurement of the sample potential in terms of its duration, intensity, execution, etc. Specifically, the parameters of the sample discharge can be set so that the sample potential essentially disappears as a result of the discharge. Thereafter, method 510 shown in Figure 5, for example, can be performed again (started in step 511 or step 512 (if the probe has already been properly positioned)). This loop is performed when the sample potential is within the range [P] min , P max This can be done as many times as desired until it reaches the desired value.

[0112] The sample potential is within the range [P] (with and without discharge 520). min , P maxIf the probe is within the range, method 530 can be performed to bring the probe closer to the sample. This method includes the following steps 531-535: step 531, bringing the probe closer to the sample; and step 532, repeatedly measuring the deviation of the probe at a predetermined rate (frequency) during the approaching process. Based at least partially on the deviation of the probe, the approach termination condition to avoid sample damage can be confirmed (or not confirmed) (step 533). If the approach termination condition is confirmed, the process of bringing the probe closer to the sample can be terminated (step 534) and / or the sample can be locally discharged (step 535). Since method 530 can confirm a very localized sample potential during the approaching process (compared to the relatively large-area scanning by method 510), it is possible to capture sample potentials that remained undetected in method 510. After the discharge of the sample 535, the process of bringing the probe closer to the sample 531 can be continued (along with the additional steps 532-535). This loop can be repeated as many times as desired, until the probe is brought closer to the sample and the target distance is reached (for example, until contact is made).

[0113] The following lists additional preferred examples of the embodiments described herein.

[0114] [Claim 1] A method (510) for determining the potential associated with a sample (160), The steps include: positioning the probe (150) above the sample (160) (511); Step (512) of applying at least a first DC voltage offset and a second DC voltage offset (121, 122), each of which is within a first range (221), The steps include applying an AC voltage to the probe (150) for the purpose of inducing mechanical vibration (141, 142) of the probe (150), Step (214) of measuring the first deviation (210, 211, 212, 230) of the probe (150) induced by the first DC voltage offset (121, 122), and the second deviation (210, 211, 212, 230) of the probe (150) induced by the second DC voltage offset (121, 122), Step (515) of determining the potential outside the interval from the first DC voltage offset (121, 122) to the second voltage offset (121, 122) based at least partially on the first and second deviations (210, 211, 212, 230) A method that includes this.

[0115] [Claim 2] The method according to claim 1, wherein the first deviation and the second deviation (210, 211, 212, 230) include the amplitude (210, 211, 212) and / or the phase (230) of the mechanical vibration (141, 142).

[0116] [Claim 3] The method according to claim 1 or 2, wherein the first deviation and the second deviation (210, 211, 212, 230) include an in-phase component (212) and an orthogonal component (211).

[0117] [Claim 4] The method according to any one of claims 1 to 3, wherein the step (514) of measuring the first deviation and the second deviation (210, 211, 212, 230) includes lock-in amplification.

[0118] [Request Item 5] The method according to any one of claims 1 to 4, wherein the frequency of the AC voltage is approximately equal to the resonant frequency of the probe (150) or is a multiple of the resonant frequency of the probe.

[0119] [Request Item 6] The method according to any one of claims 1 to 5, wherein the first range (221) extends from -10V to +10V.

[0120] [Request Item 7] The method according to any one of claims 1 to 6, wherein the step of determining the potential comprises fitting a first data point including at least the first deviation (210, 211, 212, 230) and the first DC voltage offset (121, 122), and a second data point including the second deviation (210, 211, 212, 230) and the second DC voltage offset (121, 122), using a fit function.

[0121] [Request Item 8] The method according to claim 7, wherein the step of determining the potential includes extrapolating and / or identifying points where the fit function becomes zero.

[0122] [Request Item 9] The method according to claim 7 or 8, wherein the fitting function includes a linear function, and preferably includes a correction of the linear function based on the resonant frequency of the probe (150), the vibration quality coefficient, and / or the spring constant.

[0123] [Request Item 10] The method according to any one of claims 1 to 9, wherein the positioning is performed such that the distance between the probe (150) and the sample (160) is 0.001 μm to 1000 μm, preferably 50 μm to 150 μm.

[0124] [Request Item 11] A method (530) of bringing a probe (150) closer to a sample (160), Step (531) of bringing the probe (150) closer to the sample (160), During the approach process (531), the step (532) is to repeatedly measure the displacement (210, 211, 212, 230) of the probe (150), A step (533) to confirm the approach termination conditions to avoid damaging the sample, at least partially based on the deviation (210, 211, 212, 230) of the probe (150) and A method that includes this.

[0125] [Request Item 12] The method according to claim 11, wherein the confirmation step (533) is performed by a real-time device configured to confirm the approach termination condition in 2ms or less, preferably 1ms or less, and particularly preferably 0.5ms or less.

[0126] [Request Item 13] The method according to claim 11 or 12, further comprising the step (534) of terminating the process (531) of bringing the probe (150) closer to the sample (160) based at least in part on having confirmed the approach termination condition (533).

[0127] [Request Item 14] The method according to claim 13, wherein the termination step is performed within 2 ms, preferably within 1 ms, and particularly preferably within 0.5 ms, after the occurrence of the termination condition.

[0128] [Request Item 15] The method according to any one of claims 11 to 14, wherein the process (531) of bringing the probe (150) closer is performed at a speed of 0.1 μm / s or more, preferably 1 μm / s or more, and particularly preferably 2 μm / s or more.

[0129] [Request Item 16] The method according to any one of claims 11 to 15, wherein the approach termination condition includes the probe (150) overshooting a predetermined deviation (210, 211, 212, 230).

[0130] [Request Item 17] The method according to any one of claims 11 to 16, further comprising the step of measuring the resonant frequency of the probe (150) during the approaching process (531).

[0131] [Request Item 18] The method according to claim 17, wherein the approach termination condition includes the resonant frequency overshooting a predetermined frequency shift.

[0132] [Request Item 19] The method according to claim 17 or 18, wherein the approach termination condition includes the resonant frequency undershooting a predetermined minimum frequency.

[0133] [Request Item 20] A method for processing a sample (160), A step of a method for determining the potential according to any one of claims 1 to 10, A step of a method for bringing a probe (150) toward a sample (160) according to any one of claims 11 to 19, at least in part, based on determining the potential, A method that includes this.

[0134] [Request Item 21] The method according to claim 20, further comprising the step (520) of discharging the sample (160) at least partially based on the determination of the potential.

[0135] [Request Item 22] The method according to claim 21, wherein the discharge step (520) is performed to a potential of ±1V or more, preferably ±5V or more, and particularly preferably ±10V or more.

[0136] [Request Item 23] The method according to any one of claims 11 to 19, wherein the steps of the method are performed only for potentials less than ±20V, preferably less than ±15V, and particularly preferably less than ±10V, according to claim 21 or 22.

[0137] [Request Item 24] The method according to any one of claims 1 to 23, wherein the sample (160) is charged at least partially.

[0138] [Request Item 25] The probe (150) includes a probe (150) of a scanning probe microscope. The probe (150) comprises a probe arm (151) and a measuring tip (152), and / or The aforementioned deviations (210, 211, 212, 230) are measured by the light beam reflected by the probe (150). Claims 1 to 24 One of the methods described above.

[0139] [Claim 26] The method according to any one of claims 1 to 25, wherein the sample (160) includes an object for lithography, preferably a lithography mask.

[0140] [Claim 27] An apparatus for processing a sample (160), configured to automatically perform the steps of any of claims 1 to 26.

Claims

1. A method (510) for determining the potential associated with a sample (160), The steps include: positioning the probe (150) above the sample (160) (511); Step (512) of applying at least a first DC voltage offset and a second DC voltage offset (121, 122), each of which is within a first range (221), The steps include applying an AC voltage to the probe (150) for the purpose of inducing mechanical vibration (141, 142) of the probe (150), Step (214) of measuring the first deviation (210, 211, 212, 230) of the probe (150) induced by the first DC voltage offset (121, 122), and the second deviation (210, 211, 212, 230) of the probe (150) induced by the second DC voltage offset (121, 122), Step (515) of determining the potential outside the interval from the first DC voltage offset (121,122) to the second voltage offset (121,122) based at least partially on the first and second deviations (210,211,212,230) and A method that includes this.

2. The method according to claim 1, wherein the first deviation and the second deviation (210, 211, 212, 230) include the amplitude (210, 211, 212) and / or the phase (230) of the mechanical vibration (141, 142).

3. The method according to claim 1 or 2, wherein the first deviation and the second deviation (210, 211, 212, 230) include an in-phase component (212) and an orthogonal component (211).

4. The method according to any one of claims 1 to 3, wherein the step (514) of measuring the first deviation and the second deviation (210, 211, 212, 230) includes lock-in amplification.

5. The method according to any one of claims 1 to 4, wherein the frequency of the AC voltage is approximately equal to the resonant frequency of the probe (150) or is a multiple of the resonant frequency of the probe.

6. The method according to any one of claims 1 to 5, wherein the first range (221) extends from -10V to +10V.

7. The method according to any one of claims 1 to 6, wherein the step of determining the potential includes fitting at least a first data point including the first deviation (210, 211, 212, 230) and the first DC voltage offset (121, 122), and a second data point including the second deviation (210, 211, 212, 230) and the second DC voltage offset (121, 122), using a fit function.

8. The method according to claim 7, wherein the step of determining the potential includes extrapolating and / or identifying points where the fit function becomes zero.

9. The method according to claim 7 or 8, wherein the fitting function includes a linear function, and preferably includes correction of the linear function based on the resonant frequency of the probe (150), the vibration quality coefficient, and / or the spring constant.

10. The method according to any one of claims 1 to 9, wherein the positioning is performed such that the distance between the probe (150) and the sample (160) is 0.001 μm to 1000 μm, preferably 50 μm to 150 μm.

11. A method (530) of bringing a probe (150) closer to a sample (160), Step (531) of bringing the probe (150) closer to the sample (160), During the approach process (531), the step (532) is to repeatedly measure the displacement (210, 211, 212, 230) of the probe (150), A step (533) to confirm the approach termination conditions to avoid damaging the sample, at least partially based on the deviation (210, 211, 212, 230) of the probe (150) and A method that includes this.

12. The method according to claim 11, wherein the confirmation step (533) is performed by a real-time device configured to confirm the approach termination condition in 2 ms or less, preferably 1 ms or less, and particularly preferably 0.5 ms or less.

13. The method according to claim 11 or 12, further comprising the step (534) of terminating the process (531) of bringing the probe (150) closer to the sample (160) based at least in part on having confirmed the approach termination condition (533).

14. The method according to claim 13, wherein the termination step is performed within 2 ms, preferably within 1 ms, and particularly preferably within 0.5 ms, after the occurrence of the termination condition.

15. The method according to any one of claims 11 to 14, wherein the process (531) of bringing the probe (150) closer is performed at a speed of 0.1 μm / s or more, preferably 1 μm / s or more, and particularly preferably 2 μm / s or more.

16. The method according to any one of claims 11 to 15, wherein the approach termination condition includes the probe (150) overshooting a predetermined deviation (210, 211, 212, 230).

17. The method according to any one of claims 11 to 16, further comprising the step of measuring the resonant frequency of the probe (150) during the approaching process (531).

18. The method according to claim 17, wherein the approach termination condition includes the resonant frequency overshooting a predetermined frequency shift.

19. The method according to claim 17 or 18, wherein the approach termination condition includes the resonant frequency undershooting a predetermined minimum frequency.

20. A method for processing a sample (160), A step of a method for determining the potential according to any one of claims 1 to 10, A step of a method for bringing a probe (150) toward a sample (160) according to any one of claims 11 to 19, at least in part, based on determining the potential, A method that includes this.

21. The method according to claim 20, further comprising the step (520) of discharging the sample (160) at least partially based on the determination of the potential.

22. The method according to claim 21, wherein the discharge step (520) is performed at a potential of ±1V or more, preferably ±5V or more, and particularly preferably ±10V or more.

23. The method according to any one of claims 11 to 19, wherein the steps of the method are performed only for potentials less than ±20V, preferably less than ±15V, and particularly preferably less than ±10V, according to claim 21 or 22.

24. The method according to any one of claims 1 to 23, wherein the sample (160) is charged at least partially.

25. The probe (150) includes a probe (150) of a scanning probe microscope. The probe (150) comprises a probe arm (151) and a measuring tip (152), and / or The aforementioned deviations (210, 211, 212, 230) are measured by the light beam reflected by the probe (150). The method according to any one of claims 1 to 24.

26. The method according to any one of claims 1 to 25, wherein the sample (160) includes an object for lithography, preferably a lithography mask.

27. An apparatus for processing a sample (160), configured to automatically perform the steps of the method according to any one of claims 1 to 26.

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