Method for characterizing defects in scanning electron microscopy

Abstract

A method for characterizing a defect in a scanning electron microscope (100), the scanning electron microscope (100) being suitable for analyzing and / or processing a sample (10), in particular a lithography mask, using an electron beam (106), the method comprising the steps of: a) bringing the scanning electron microscope (100) to an equilibrium state (S1); b) introducing a trigger event (S2) into the scanning electron microscope (100) that disturbs the equilibrium state; c) detecting a response behavior of the scanning electron microscope (100) to the trigger event (S3); and d) comparing the detected response behavior with an expected response behavior for characterizing the defect (S4).

Description

TECHNICAL FIELD

[0001] The present invention relates to a method, an apparatus, and a computer program product for characterizing disturbances in a scanning electron microscope.

[0002] The content of priority application DE 10 2022 119 752.2 is incorporated herein by reference in its entirety.

BACKGROUND ART

[0003] Microlithography is used, for example, for the production of microstructured components such as integrated circuits. The microlithography process is performed using a lithographic apparatus having an illumination system and a projection system. The image of a mask (also referred to as a reticle mask or a lithography mask) illuminated by the illumination system is projected by the projection system onto a substrate, for example a silicon wafer, which is coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system, to transfer the mask structure to the photosensitive coating of the substrate.

[0004] Masks are used for a large number of exposures. Accordingly, it is very important that they are free of defects. Considerable efforts are accordingly being made to inspect masks for defects and to repair the identified defects. Such mask defects can be on the order of a few nanometers. The repair of such defects requires an apparatus that provides a very high spatial resolution for the repair process.

[0005] An apparatus suitable for this purpose is an apparatus that activates local etching or deposition processes on the basis of particle beam-induced processes. For example, EP 1 587 128 discloses such an apparatus. According to this publication, an electron beam from an electron microscope is used to trigger a chemical process.

[0006] The electron beam columns of such electron microscopes, particularly scanning electron beam microscopes (hereinafter referred to as "scanning electron microscopes" or "SEMs"), must periodically meet certain stability criteria in order to ensure the high-precision inspection and processing of the lithography masks described earlier. These stability criteria include, for example, the beam position or beam profile of the generated electron beam. The stability of the electron beam column can be reduced by various external and internal faults. External faults include, for example, temperature and pressure fluctuations, vibrations, or the effects of magnetic fields. Internal faults can be caused by changes in the magnetic or electric field within the electron beam column. Changes in the electric field are usually due to contamination, which can alter the charge.

[0007] Identifying and mitigating such problems is actually complex and can take several days. This is especially true when the scanning electron microscope is already in use with the customer and the electron microscope manufacturer has limited access to it. [Overview of the Initiative]

[0008] Against this backdrop, the present invention aims to provide an improved method, in particular a rapid and targeted method, for characterizing defects in scanning electron microscopy.

[0009] Therefore, a method for characterizing defects in a scanning electron microscope is provided. A scanning electron microscope is suitable for analyzing and / or processing a sample (also called a "probe"), particularly a lithography mask, using an electron beam, and the method comprises the steps of a) introducing a trigger event to the scanning electron microscope, b) detecting the response behavior of the scanning electron microscope to the trigger event, and c) comparing the detected response behavior with a predicted response behavior for the characterization of the defect.

[0010] In this way, it is possible to quickly and easily characterize defects in scanning electron microscopes.

[0011] In this specification, any focused particle beam system, such as a helium ion microscope, can be used instead of a scanning electron microscope.

[0012] For example, the present method, or a method according to further embodiments, may have one or more of the following steps: i) recording an SEM image of a reference object that does not move within the chamber of the electron beam column; ii) calculating the offset of the recorded SEM image (the image offset corresponds to a change in the position of the electron beam); iii) comparing the image sharpness of the recorded SEM image; iv) calculating changes in electron beam column parameters such as focus, stigmeter, or aperture (by optimizing these parameters, if appropriate, by what is called an automated function); v) introducing a trigger event; and repeating steps i) to v).

[0013] In one embodiment, the scanning electron microscope is brought to equilibrium before step a), and the trigger event in step a) is such that it disrupts the equilibrium.

[0014] The inventors have surprisingly found that faults can be visualized particularly efficiently by using a scanning electron microscope, especially by de-equilibriumizing its electron beam column and detecting and analyzing its response behavior. One advantage of this approach is that it simplifies the control of the scanning electron microscope, for example, because it is always possible to record an image of a reference object. In contrast, if a trigger event is simply introduced to the scanning electron microscope without prior equilibriumizing it, such images, if any, are only available, or can be used, with difficulty, as a basis for analyzing the response behavior.

[0015] In this context, equilibrium is understood to mean the state of a scanning electron microscope where the electron dose in the beam path of the electron beam column is constant over time. This means that the electron dose at location O1 at time t1 is equal to the electron dose at location O1 at another time t2, and these are either the same or essentially the same, or, in the case of a periodic process, the electron dose in the beam path of the electron beam column is constant on average over time. The electron dose is determined as a function of current and voltage.

[0016] The sample is specifically a lithography mask, i.e., a mask intended for use in a lithography apparatus. This could be an EUV or DUV lithography apparatus. EUV stands for "extreme ultraviolet" and refers to a working light wavelength of 0.1 nm to 30 nm. DUV stands for "deep ultraviolet" and refers to a working light wavelength of 30 nm to 250 nm.

[0017] In one embodiment, N images are recorded to bring the system into equilibrium, where N is preferably greater than 3 and more preferably greater than 10.

[0018] By recording N images (particularly of the reference object), the equilibrium state of a scanning electron microscope can be easily established and maintained. For example, images may be captured for 10 seconds every 2 minutes. During this time, the electron beam reaches the reference object. For the remaining time, i.e., 1 minute and 50 seconds, the electron beam is directed to the aperture of the scanning electron microscope using, for example, an electrostatic or magnetic deflector. In particular, the period assumed to record each of the N images may be shorter than the period between two consecutive images.

[0019] References include, for example, lithography masks, dissolved samples, or other samples with structures in the nm region, Faraday cups with structures in the nm region, or shielding elements for charge compensation to prevent charging of samples (especially lithography masks) during normal operation (in particular, meshes described in DE 10 2020 124 306).

[0020] In a further embodiment, bringing the system to equilibrium involves recording the position and / or clarity of the electron beam as a function of time and comparing it to a threshold, the initiation of step a) depends on this comparison.

[0021] From the comparison of the above parameters and thresholds, it can be concluded that the scanning electron microscope is indeed in equilibrium. In this case, it is possible to initiate the trigger event. Alternatively, the step of bringing the system into equilibrium may involve a predefined operation (e.g., the aforementioned image recording) followed by a predefined waiting period. In this way, it is equally possible to ensure that the equilibrium state is achieved. Only after this can step a) be initiated.

[0022] In further embodiments, the response behavior detected in step b) is, in particular, the position, sharpness, focus, stigmeter, and / or coma aberration of the electron beam as a function of time.

[0023] In this context, "focus" is understood to mean the beam diameter of the electron beam. A stigmeter explains the dispersion of the beam cross-section in two mutually orthogonal directions. Coma aberration explains the deformation of the electron beam resulting from its passage through a lens located outside the optical axis. The change in position over time is also called "drift."

[0024] Such a response behavior can be easily detected, particularly in an image of a reference object generated by a scanning electron microscope. In this way, the response behavior can be generated via image information arising from the spatially invariant imaging of the reference object. For this purpose, the change in position is determined using an offset of individual elements within the image or preceding elements of the complete image or another reference. To determine the parameters that alter the sharpness of the image (focus, astigmatism-free state, coma aberration), either a comparison of the altered images themselves or a comparison of processed images (such as evaluation of the Fourier spectrum) can be adopted, or an electron beam optimization that finds a new optimization by recording a plurality of images with altered beam characteristics can be performed.

[0025] In a further embodiment, the trigger event comprises a change in sample current, a change in acceleration voltage, part of a switch-on sequence, a change in process gas composition or process gas pressure, and / or a change in electron beam cross-sectional area or electron beam position.

[0026] In principle, any adjustment of the electron microscope is a possible trigger if the change thereof causes a change in electron dose or electron energy. This includes variations in lens current for electron expansion and focusing at any position within the system, variations in acceleration voltage and other voltages within the system, or variations in electron deflection by deflection coils of electrostatic deflectors, mechanical elements, and emission sources.

[0027] The sample current is understood to mean the current of the electron beam detected in the region of the sample.

[0028] A part of the switch-on sequence is understood to mean switch-off and / or switch-on of the acceleration voltage, closing / opening of a valve, and the like.

[0029] Suitable process gases suitable for material deposition and elevated structure growth are, in particular, alkyl compounds of main group elements, metals, or transition elements. Examples thereof include (cyclopentadienyl)trimethylplatinum CpPtMe3 (Me=CH4), (methylcyclopentadienyl)trimethylplatinum MeCpPtMe3, tetramethyltin SnMe4, trimethylgallium GaMe3, ferrocene Cp2Fe, bis-allylchromium Ar2Cr, and / or carbonyl compounds of main group elements, metals, or transition elements (for example, chromium hexacarbonyl Cr(CO)6, molybdenum hexacarbonyl Mo(CO)6, tungsten hexacarbonyl W(CO)6, dicobalt octacarbonyl Co2(CO)8, triruthenium dodecacarbonyl Ru3(CO) 12 , iron pentacarbonyl Fe(CO)5, etc.), and / or alkoxide compounds of main group elements, metals, or transition elements (for example, tetraethyl orthosilicate Si(OC2H5)4, tetraisopropoxytitanium Ti(OC3H7)4, etc.), and / or halogen compounds of main group elements, metals, or transition elements (for example, tungsten hexafluoride WF6, tungsten hexachloride WCl6, titanium tetrachloride TiCl4, boron trifluoride BF3, silicon tetrachloride SiCl4, etc.), and / or complexes containing main group elements, metals, or transition elements (for example, copper bis(hexafluoroacetylacetonate) Cu(C5F6HO2)2, dimethylgold trifluoroacetylacetonate Me2Au(C5F3H4O2), etc.), and / or organic compounds such as carbon monoxide CO, carbon dioxide CO2, aliphatic hydrocarbons, and / or aromatic hydrocarbons.

[0030] Suitable process gases suitable for material etching are, for example, xenon difluoride XeF2, xenon dichloride XeCl2, xenon tetrachloride XeCl4, water vapor H2O, heavy water D2O, oxygen O2, ozone O3, ammonia NH3, nitrosyl chloride NOCl, and / or one of the following halogen compounds: XNO, XONO2, X2O, XO2, X2O2, X2O4, X2O6 (X is a halide). Further process gases for material etching are defined in the applicant's U.S. Patent Application No. 13 / 0 103 281.

[0031] In further embodiments, steps a) to c) (which may include a step of bringing the system to equilibrium) are performed for a first trigger event and repeated for a second trigger event, the first and second trigger events being selected such that the electron dose at a first location in the beampath of the electron beam has a first value when the first trigger event occurs and a second value different from the first value when the second trigger event occurs, and the electron dose at a second location in the beampath of the electron beam has a first value when the first trigger event occurs and a second value equal to the first value when the second trigger event occurs, and in the step following step c), a fault is assigned to the first location, depending on the comparison in step c) for the first and second trigger events.

[0032] In other words, this embodiment is configured such that two different trigger events cause changes in the target region (first location) due to the introduced electron dose, based on the discovery that the location of a fault can be identified in that it has the effect (secondary effect) of causing similar changes in one or more other locations. In this way, the location of the fault can be identified, allowing for targeted repairs or, for example, replacement of the correct part of the electron beam column.

[0033] In further embodiments, a first trigger event includes focusing the electron beam with an anode and / or aperture diaphragm, with the sample current collected in a Faraday cup; and a second trigger event includes trimming the electron beam with an anode and / or aperture diaphragm, with the sample current similarly collected in a Faraday cup.

[0034] For example, in an electron beam column, the sample current (in this context, "sample current" means the electron current directed toward the reference object) can be generated by a change in lens current, which either focuses the beam through an aperture (high current) or widens the beam before the aperture (low current). In other systems, the electron beam is guided through smaller or larger apertures, such as aperture slides or multi-aperture apertures, or by electromagnetic deflectors that direct the beam to the desired aperture.

[0035] In one embodiment, using a Faraday cup in the configuration allows for changing the electron dose within the system so that the electron beam for image recording is directed towards the edge of the Faraday cup. In the case of a trigger, electrons are directed into the Faraday cup.

[0036] In further embodiments, the first trigger event includes a change in current in the electron source for generating an electron beam, and the second trigger event includes an increase in sample current using capacitor excitation.

[0037] In further embodiments, the first trigger event includes the electron beam passing through the aperture, and the second trigger event includes an increase in the sample current.

[0038] In this context, "aperture" refers to a multi-aperture aperture in the case of a single capacitor, and a single-aperture aperture in the case of a double capacitor.

[0039] In further embodiments, a first trigger event includes completely shielding the electron beam at the aperture, and a second trigger event includes focusing the electron beam into the Faraday cup.

[0040] The above variations demonstrate a clever selection of first and second trigger events that are highly important to the location of the error or fault.

[0041] In further embodiments, the response behavior in step b) and / or c) includes vertical displacement, or jump, and / or damping characteristics, or transient response.

[0042] Vertical displacement (especially in terms of its magnitude) or damping characteristics (e.g., the time it takes for a detected parameter to fall below a defined threshold) can be easily evaluated.

[0043] In one embodiment, steps a) to c) (which may include a step of bringing the system to a state of equilibrium) are fully automated.

[0044] This allows scanning electron microscope manufacturers' customers to quickly implement the method, especially in the field.

[0045] In a further embodiment, a computer program product is provided which includes commands, and when the program is executed by a computer, causes the computer to perform the above method.

[0046] Computer program products, such as computer program media, can be provided or supplied, for example, as storage media such as memory cards, USB sticks, CD-ROMs, DVDs, or as files downloadable from a server on a network. For example, in a wireless communication network, this can be achieved by transferring appropriate files using a computer program product or computer program means.

[0047] The embodiments or features of this method described above are applicable to the corresponding apparatus (described below) and computer programs, and vice versa.

[0048] In this context, "a" and "an" should not necessarily be understood as being limited to exactly one element. Instead, multiple elements, such as two, three, or more, may be provided. Furthermore, any other numbers used here should not be understood as being limited to exactly the specified number of elements. Instead, numerical deviations up or down are possible unless otherwise specified. In addition, the described method steps may be performed in a different order, for example, first step b), then step a), unless otherwise specified.

[0049] Further possible implementations of the present invention include combinations of features or embodiments described above or below with respect to exemplary embodiments, which are not explicitly mentioned. In this case, those skilled in the art will also add individual embodiments as improvements or supplements to each basic form of the present invention.

[0050] Further advantageous structures and aspects of the present invention are the subject of the dependent claims and the exemplary embodiments of the present invention described below. The present invention is described below in detail based on preferred embodiments with reference to the accompanying drawings. [Brief explanation of the drawing]

[0051] [Figure 1] A schematic diagram of the processing arrangement for checking and / or repairing lithography masks is shown. [Figure 2] Figure 1 shows the electron beam column configuration for the processing setup. [Figure 3] A flowchart of the method according to one embodiment is shown. [Figure 4] A flowchart of a further method according to one embodiment is shown. [Figure 5] This diagram shows a wafer inspection or measurement system for 3D volume inspection using a dual-beam device. [Figure 6] This diagram shows the slicing and imaging methods for wafer volume inspection. [Figure 7] A wafer inspection system according to one embodiment is shown. [Modes for carrying out the invention]

[0052] In the diagrams, identical or functionally identical elements are given the same reference symbol, as long as at least one is specified. Please also note that representative diagrams are not necessarily accurate to scale.

[0053] Figure 1 shows a schematic diagram of an embodiment of a processing setup 100 (hereinafter also referred to as the “apparatus”) in the form of a scanning electron microscope. The processing setup 100 has the function of checking and / or repairing a sample, for example, a lithography mask 10. The lithography mask 10 is intended for use, for example, in an EUV or DUV lithography apparatus (not shown).

[0054] The processing setup 100 includes an electron beam column 102, which has an electron source 104 that generates an electron beam 106. The electron beam 106 strikes the lithography mask 10. Backscattered electrons are detected by the detector unit 108 of the electron beam column 102. Therefore, it is possible to create a high-resolution image of the lithography mask 10 (electron beam microscope).

[0055] The electron beam column 102 is located inside the vacuum housing 110. The same applies to the lithography mask 10 located on the sample stage 112 below the electron beam column 102. The vacuum inside the vacuum housing 110 is generated using a vacuum pump 114. For example, inside the vacuum housing 110 -7 millibars ~10 -8 There is a residual gas pressure of millibars.

[0056] The electron beam column 102 can interact with supplied process gas, which is supplied from an external gas supply unit 116 via a gas conduit 118 to the region of the electron beam 106's focal point, for example, to perform electron beam-induced processing (EBIP) operations. This particularly includes the deposition of material onto a material on a lithography mask 10 or the etching of material therefrom. In particular, the control computer 120 of the processing setup 100 is configured to control the electron beam column 102, the sample stage 112, and the gas supply unit 116 in a manner suitable for this purpose.

[0057] In particular, a computer program 122 is recorded in the control computer 120, which activates the processing configuration 100 to perform the method described below in relation to Figure 3.

[0058] Figure 2 shows the electron beam column 102 in Figure 1 in more detail. Compared with Figure 1, Figure 2 also shows that the electron beam column 102 of the electron source 104 includes an anode aperture 200 located downstream of the beam path. Following the anode aperture 200, the beam path is followed by an aperture diaphragm 202 with a single aperture. The beam path section 204 between the anode aperture 200 and the aperture diaphragm 202 is assigned the first capacitor 206 of the double capacitor 208. A further diaphragm 210 follows the aperture diaphragm 202. The beam path section 212 between the aperture diaphragm 202 and the further diaphragm 210 (which may be, for example, a pressure stage diaphragm) is surrounded by the second capacitor 212 of the double capacitor 208. Following the diaphragm 210, the detector unit 108, already described in relation to Figure 1, follows in the beam path. In detail, it may include an ESB (energy-selective backscatter) detector 214 and an SE (secondary electron) detector 216, with a filter grid 220 positioned between them. A further beam path section 218 following the detector unit 108 is surrounded by a magnetic lens 221. The electron beam 106 eventually exits the electron beam column 102 and is directed towards the lithography mask 10 (or reference object 10' in the method described below) via a scanning coil 222 and an electrostatic lens 226, which are responsible for scanning the lithography mask 10.

[0059] The above-described structure of the electron beam column 102 should be considered purely illustrative, and different designs are possible in various regions. For example, a single capacitor can be used instead of the double capacitor 208.

[0060] Referring to Figure 3, a flowchart illustrating one embodiment of the processing sequence is described below. This processing sequence can be executed by the computer program 122 described in relation to Figure 1, particularly within the processing arrangement 100.

[0061] In the optional step S1, the scanning electron microscope 100 is brought to equilibrium. This can be achieved, for example, by the scanning electron microscope 100 using the detector unit 108 to record N images of the chamber of the scanning electron microscope 100, in particular of the reference object 10', which are not shown in detail. Here, N is preferably greater than 3 and more preferably greater than 10. The time taken to record the images may be, for example, 10 seconds, and the interval between images may be 1 minute 50 seconds. These values ​​are merely illustrative and can be adapted to each application. Typically, the scanning electron microscope 100 reaches equilibrium after recording 3 to 10 images.

[0062] In step S1, the position and / or clarity of the electron beam 106 (see Figures 1 and 2) can be detected as a function of time and compared with thresholds to check whether such an equilibrium state has actually been reached. For example, if the drift falls below a defined threshold, this confirms that an equilibrium state has been achieved, and the method can proceed to step S2.

[0063] In step S2, a trigger event that disrupts the equilibrium is introduced to the scanning electron microscope 100. This means that the scanning electron microscope 100, or in particular the electron column 102, is de-equilibrium. This means, for example, the following:

[0064] In equilibrium, the electron dose in specific beampath sections 204, 212, and 218, as shown in Figure 2, is constant over time or constant at the time of recording each of the N images (for example, the electron dose in beampath section 204 when recording the first of the N images is equal to the electron dose in beampath section 204 when recording the second of the N images). However, when the equilibrium is disturbed, the electron dose in specific beampath sections 204, 212, and 218 changes over time. In specific sections, the electron beam dose can be calculated, for example, from the electron current and electron voltage.

[0065] Possible trigger events include, for example, changes in sample current, changes in acceleration voltage, part of the switch-on sequence, changes in process gas composition or process gas pressure, or changes in electron beam cross-section or electron beam position.

[0066] In a further step S3, the response behavior of the electron beam microscope 100 or electron beam column 102 is detected. For example, the position, focus, stigmeter, and / or coma aberration of the electron beam 106 can be detected using the detector unit 108 (see Figures 1 and 2). In particular, it is also possible to detect or calculate the derivatives of the aforementioned parameters in step S3. In the subsequent step S4, the detected response behavior is compared with the expected response behavior. Faults are characterized based on this comparison.

[0067] The expected response behavior is recorded, for example, in tests preceding the methods of steps S1-S4, particularly before the scanning electron microscope 100 is delivered to the customer. A specific fault can be concluded from a comparison of the detected behavior with the expected response behavior. This correlation can then be verified experimentally before performing the methods of steps S1-S4, particularly before providing the scanning electron microscope to the customer. This experience-based knowledge can be included in the fault determination in step S4. For example, the fault may be contamination in any of the beam path sections 204, 212, or 218. Such contamination has a predetermined effect on the response behavior of the electron beam column 102. In particular, step S4 allows for the verification of response behavior related to vertical displacement and / or collapse characteristics.

[0068] By carefully selecting trigger events, the location of a fault can also be identified. For this reason, the method in steps S1-S4 is performed for a first trigger event and repeated for a second trigger event, as shown in step S5 of the method. The first and second trigger events are selected, for example, so that the electron dose in beam path section 204 (Figure 2) has different values. In contrast, the electron doses in other beam path sections of the electron beam column 102 (identified here by reference numbers 212 and 218 as examples) remain constant. In step S6 of the method, following step S4, if a fault was detected for the first trigger event in step S4, but no such fault was detected for the second trigger event (in step S4 of the repetition of steps S1-S4), then it can be concluded that the fault or its cause must be in beam path section 204. This is because the conditions (electron beam dose) in the other sections of the electron beam column 102 do not change. Therefore, a charge reversal must have occurred in electron beam section 204. Therefore, the corresponding evaluations shown in the following table can be performed in method step S6.

[0069] [Table 1]

[0070] The second trigger event is also called an identifier because it helps classify the fault detected in the first trigger event, for example, as an actual fault, no fault, or invalid measurement, and by assigning the fault detected in the first trigger event to a specific location on the electron beam column 102.

[0071] The inventors discovered that subsequent trigger events yielded surprisingly good results in determining the locality of the failure.

[0072] For example, in the first trigger event, the electron beam 106 is focused through the anode diaphragm 200 (see Figure 2) or aperture diaphragm 202. The sample current 228 does not hit the sample 10 but is collected in the Faraday cup 10'. Due to the focusing of the electron beam 106, it is not trimmed by the anode diaphragm 200 or aperture diaphragm 202. In contrast, the second trigger event assumes trimming of the electron beam 106 by the anode diaphragm 200 and / or aperture diaphragm 202. The sample current 228 is similarly collected in the Faraday cup. As a result, only the electron dose in beam path section 204 ultimately changes (comparing the first trigger event to the second trigger event). In contrast, the electron dose in sections 212, 218, and all other regions remains constant within the electron beam column 102.

[0073] A further advantageous trigger event (first trigger event) has been found to be a change in the current of the electron source 104. In this case, the second trigger event involves an increase in the sample current 228 using a capacitor. For this purpose, the electron beam is focused by the aperture 210 using, for example, a condenser lens (in particular, the first).

[0074] A further first trigger event is assumed to be the electron beam 106 passing through the aperture 210. A second trigger event increases the sample current 228. For example, the sample current is changed using a multi-aperture aperture with different diameters. Alternatively, the beam diameter is changed as it passes through the aperture 210 (for example, via increased excitation in a condenser lens).

[0075] In a further variation, the first trigger event includes completely shielding the electron beam 106 at the aperture 210. In the second trigger event, the electron beam 106 is collected in a Faraday cup.

[0076] Figure 4 shows one possible implementation of the method described in relation to Figure 3. In the method according to Figure 4, in step T1, the electron beam microscope 100 is started in repair mode or standby mode. In step T2, the electron beam microscope 100, in particular the electron beam column 102, is initialized. In step T3, an image of the sample 10 is recorded using the detector unit 108. In step T4, the clarity of the detected image is measured. In step T5, the image offset is measured. In step T6, it is decided whether to initiate the trigger event in step T7. This is done if it is found that the electron microscope 100 is in equilibrium ("yes"). If this is not yet true ("no"), this is awaited in step T8. In step T9, it is decided whether the process is complete. If not, it is repeated.

[0077] Figure 5 shows an embodiment of a wafer inspection system 1000 for 3D volume inspection. A coordinate system is selected such that the wafer surface 55 coincides with the XY plane.

[0078] To investigate the 3D inspection volume within a semiconductor wafer, a slicing and imaging method applicable to inspecting volumes inside the wafer has been proposed. In one embodiment, a 3D volume image is generated from the inspection volume inside the wafer by a so-called "wedge-cut" approach or wedge-cut geometry, without the need to remove a sample piece from the wafer. The slicing and imaging method is applied to inspection volumes having dimensions of several micrometers (e.g., having a transverse length of 5 to 10 micrometers in a wafer with a diameter of 200 mm or 300 mm). The transverse length may be longer, reaching up to 30 or 50 micrometers. A V-shaped groove or edge is milled into the top surface of the integrated semiconductor wafer to allow access to a cross-sectional surface at an angle to the top surface. The 3D volume image of the inspection volume is acquired at a limited number of inspection locations, for example, in a process control monitor (PCM), for example, at a representative location on a die, or at a location identified by another inspection tool. The slicing and imaging method destroys only the wafer locally, allowing other dies to remain usable, or the wafer to be used for further processing. Methods and inspection systems for 3D volume imaging are described in WO2021 / 180600, which are fully incorporated herein by reference.

[0079] The wafer inspection system 1000 is configured for slicing and imaging methods under a wedge-cut geometry using a dual-beam system 1. For wafer 8, multiple inspection locations, including inspection locations 6.1 and 6.2, are defined in a location map or inspection list generated from an inspection tool or design information. Wafer 8 is placed on a wafer support 15. The wafer support 15 is mounted on a stage 155 equipped with actuators and position control. Actuators and means for precise control of the wafer stage, such as laser interferometers, are known in the art. A control unit 16 is configured to control the wafer stage 155 and adjust inspection location 6.1 of wafer 8 at the intersection 43 of the dual-beam device 1. The dual-beam device 1 comprises a focused ion beam (FIB) column 50 (having an FIB optical axis 48) and a charged particle beam (CPB) imaging system 40 (having an optical axis 42). At the intersection 43 of the optical axes of both the FIB and CPB imaging systems, the wafer surface 55 is positioned at an inclination angle GF with respect to the FIB axis 48. The FIB axis 48 and the CPB imaging system axis 42 form an angle GFE, and the CPB imaging system axis forms an angle GE with respect to the normal to the wafer surface 55. In the coordinate system of Figure 5, the normal to the wafer surface 55 is given by the z-axis. The focused ion beam (FIB) 51 is generated by the FIB column 50 and collides with the surface 55 of the wafer 8 at an angle GF. The inclined cross-sectional surface is milled onto the wafer by ion beam milling at inspection site 6.1 under approximately an inclination angle GF. In the embodiment of Figure 5, the inclination angle GF is approximately 30°. The actual inclination angle of the inclined cross-sectional surface may deviate by up to 1° to 4° from the inclination angle GF due to the beam divergence of the focused ion beam, such as a gallium ion beam. The FIB column 50 may be, for example, a gallium FIB or an FIB having a field ion source (GFIS) containing other types of ion species such as xenon ions or argon ions. The charged particle beam imaging system 40 is tilted downward at an angle GE with respect to the wafer normal, and an image of the milled surface is acquired.In the embodiment shown in Figure 5, the tilt angle GE is approximately 15°. However, other configurations are also possible, such as GE=GF so that the CPB imaging system axis 42 is perpendicular to the FIB axis 48, or GE=0° so that the CPB imaging system axis 42 is perpendicular to the wafer surface 55.

[0080] During imaging, a beam of charged particles 44 is scanned by a scanning unit of the charged particle beam imaging system 40 along a scanning path on the cross-sectional surface of the wafer 8 at inspection location 6.1, generating secondary and scattered particles. For example, a secondary electron particle detector 17.1 collects at least some of the secondary and scattered particles and communicates the particle count to the control unit 19. Other detectors may be provided for other interaction products. For example, an in-lens detector 17.2 may be provided for the collection of backscattered charged particles. The control unit 19 controls the charged particle beam imaging column 40, the FIB column 50, and is connected to the stage control unit 16 to control the position of the wafer 8 mounted on the wafer support 15 via the wafer stage 155. The control unit 19 communicates with the operation control unit 2. The operation control unit 2 triggers the positioning and alignment of the wafer 8 at inspection location 6.1 at intersection 43, for example, via the movement of the wafer stage, and triggers repeated operations of FIB milling, image acquisition, and stage movement.

[0081] Each new intersecting surface is milled by the FIB beam 51 and imaged by the charged particle imaging beam 44 (e.g., a scanning electron beam or a helium ion beam from a helium-ion microscope (HIM)). In one embodiment, the dual-beam system comprises a first focused ion beam system 50 positioned at a first angle GF1 and a second focused ion column positioned at a second angle GF2, where the wafer is rotated between milling at the first angle GF1 and the second angle GF2, while imaging is performed by, for example, an imaging charged particle beam column 40 positioned perpendicular to the wafer surface 55.

[0082] The dual-beam system 1 further includes a gas injection system (GIS) 79 in which a gas nozzle is connected to at least one gas reservoir (not shown) via a valve (not shown). This provides a controlled amount of precursor gas during milling and imaging, which can, for example, generate a metal coating. For example, it can generate alignment marks or fiducials. For example, a tungsten metal coating can be generated by providing tungsten hexacarbonyl. The metal coating can be formed by ion beam milling, and alignment markers or fiducials are formed near the inspection site. This enables precise positioning and image alignment of multiple cross-sectional images. Milling by FIB51 can be enhanced by using a dedicated precursor gas. For example, it can improve the uniformity of milling in different material compositions and reduce curtening. The material composition in the semiconductor wafer may include silicon, silicon dioxide, silicon nitride, copper, aluminum, or other materials.

[0083] Preferred precursor gases include at least one of ammonia, ammonium hydroxide, ammonium carbamate, bromine, chlorine, hydrazine, hydrogen peroxide, sardidine, iodine, diiodoethane, isopropanol, methyl difluoroacetate, nitroethane, nitroethanol, nitrogen, nitrogen tetroxide, nitrogen trifluoride, nitromethane, nitropropane, nitrobutane, oxygen, ozone, PMCPS, tungsten hexacarbonyl, water, or xenon difluoride. However, other gases are also possible. For example, acetyl methoxy chloride, methyl acetate, methyl nitroacetate, ethyl acetate, ethyl nitroacetate, propyl acetate, propyl nitroacetate, ethyl nitroacetate, methyl methoxyacetate, and acetyl methoxy chloride, acetic acid or thiol acetate, hexafluoroacetylacetone, silazane, trifluoroacetamide, dicobalt octacarbonyl, molybdenum hexacarbonyl, and combinations thereof are also possible.

[0084] Furthermore, the dual-beam system 1 further includes a contact pin 81. The contact pin 81 is connected to a manipulator (not shown) for precise movement of the contact pin 81 under the control of the charged particle beam 44 during image acquisition. This allows structures present on the wafer surface to be contacted and electrically connected to the control device 19.

[0085] Figure 6 shows the wedge-cut geometry in an embodiment of a 3D memory stack. Figure 6 shows the situation when surface 52 is the last milled cross-sectional surface milled by FIB 51. Cross-sectional surface 52 is scanned by a SEM beam 44 positioned perpendicularly incident to the wafer surface 55, for example, in the embodiment of Figure 6, to generate a high-resolution cross-sectional image slice. Cross-sectional surfaces 53.1…53.N are subsequently milled by the FIB beam 51 at an angle GF of approximately 30° relative to the wafer surface 55, however other angles GF (e.g., GF=20° to GF=60°) are also possible. The cross-sectional image slice includes a first cross-sectional image feature formed by intersections with high aspect ratio (HAR) structures or vias (e.g., the first cross-sectional image features of HAR structures 4.1, 4.2, and 4.3) and a second cross-sectional image feature formed by intersections with layers L.1…LM containing, for example, SiO2, SiN, or tungsten wires. Some of the lines are also called "word lines." The maximum number of layers M is usually more than 50, for example, more than 100, and even more than 200. The HAR structures and layers extend across most of the wafer volume, but may contain gaps. The HAR structures typically have a diameter of less than 100 nm, for example, about 80 nm, or for example, 40 nm. Thus, the cross-sectional image slice contains a first cross-sectional image feature as the intersection or cross-section of the HAR structures at different depths (Z) at each XY position. In the case of a cylindrical vertical memory HAR structure, the resulting first cross-sectional image feature is a circular or elliptical structure at various depths determined by the position of the structure on the inclined cross-sectional surface 52. The memory stack extends in the Z direction perpendicular to the wafer surface 55. The thickness d or minimum distance d between two adjacent cross-sectional image slices is typically adjusted to a value on the order of a few nm, for example, 30 nm, 20 nm, 10 nm, 5 nm, 4 nm, or even smaller. When a layer of material of a predetermined thickness d is removed by FIB, the following cross-sectional surfaces 53.i…53.J are exposed and become accessible for imaging with the charged particle imaging beam 44.By repeating milling and imaging, multiple cross-sections are formed, yielding multiple cross-sectional images. This allows for proper sampling of the inspection volume with size LX × LY × LZ, enabling the generation of, for example, a 3D volume image. This limits the damage to the wafer to the inspection volume 160 plus the damage volume in the y-direction with length LYO. If the inspection depth LZ is approximately 10 μm, the additional damage volume in the y-direction is typically limited to less than 20 μm.

[0086] Figure 7 shows a further embodiment of the improved wafer inspection system. The wafer inspection system 1000 comprises a dual-beam system 1. The dual-beam system is shown in Figure 5, and see also the description of Figure 5. Basic features of the dual-beam system 1 may include a first charged particle or FIB column 50 for milling and a second charged particle beam imaging system 40 for high-resolution imaging of the cross-sectional surface. The dual-beam system 1 comprises at least one detector 17 for detecting secondary particles which may be electrons or photons. In this embodiment, the first detector 17.1 is located near the interaction volume of the primary beam 44 with the wafer 8 and is configured to attract and collect secondary electrons. The second in-lens detector 17.2 is located within the imaging charged particle beam system 40 and is configured to collect backscattered electrons. The dual-beam system 1 further comprises a wafer stage 155 configured to hold the wafer 8 during use. The wafer stage 155 includes actuators for lateral and axial displacement or rotation of the wafer stage 155. For example, the wafer stage includes a long-stroke actuator for displacing the wafer 8 from a first inspection location 6.1 to a second inspection location 6.2 (see Figure 5), and a high-precision short-stroke actuator for precise adjustment of the wafer 8 at the inspection location. The wafer stage 155 has all three (rotation around the x, y, and z axes) to six degrees of freedom for positional adjustment and movement. The dual-beam system 1 further includes a control unit 19, which consists of memory and logic for controlling the operation of the dual-beam system 1.

[0087] The wafer stage 155 is positioned by a stage control unit 16. The stage control unit 16 is connected to a high-precision position sensor 21 configured to measure the position of the wafer stage 155 relative to the charged particle beam imaging system 40 in at least two degrees of freedom (x, y) during use. In one embodiment, the charged particle beam imaging system 40 and the high-precision position sensor 21 are mounted on a rigid support or measuring frame 25 which serves as a reference for measuring the relative position between the wafer stage 155 and the charged particle imaging beam 44. Examples of the high-precision position sensor 21 include a laser interferometer, a grid interferometer, a capacitive sensor, or a confocal sensor. The high-precision position sensor 21 is configured to perform at least one position measurement 27 of the position of the wafer stage 155 relative to the measuring frame 25 during use.

[0088] During use, the charged particle beam source 31 generates charged particles. The dual-beam system 1 further includes a deflection scanner 29 for raster scanning of the charged particle imaging beam 40. The dual-beam system 1 further includes an objective lens 33 for focusing the charged particle imaging beam 40 onto a cross-sectional surface 53. The deflection scanner 29 and the objective lens 33 are connected and controlled by a control unit 19.

[0089] The dual-beam system 1 of the embodiment shown in Figure 7 further includes a condition monitor 23 configured as a measurement system for measuring environmental influences during image acquisition. The condition monitor 23 includes at least one of a group of measurement systems, including an electromagnetic field sensor, a vibration sensor, a temperature sensor, and a gravity sensor. The condition monitor 23 is connected to a control unit 19 and is configured to provide multiple measurements of environmental influences during image scanning at multiple representative dwell points during image acquisition.

[0090] The wafer inspection system 1000 further includes an operation control unit 2. The operation control unit 2 includes at least one processing engine 201, which may consist of multiple parallel processors including a GPU processor and a common integrated memory. The operation control unit 2 further includes SSD memory, disk memory, or storage 203 for storing data including, for example, training data, trained machine learning algorithms, and multiple cross-sectional images. The operation control unit 2 further includes a user interface 205. The user interface 205 includes a user interface display 400 and a user command device 401, and is configured to receive input from the user and display quotes or results to the user. The operation control unit 2 further includes memory or storage 219 for storing process information of the image generation process of the dual beam device 1 and for storing software instructions 3 that can be executed by the processing engine 201.

[0091] The motion control unit 2 is further connected to the interface unit 231. The interface unit 231 is configured to receive further commands and data, such as CAD data, from an external device or network. The interface unit 231 is also configured to exchange information. For example, it is configured to receive commands from an external device, provide measurement results to an external device, or store a series of training data, trained machine learning algorithms, and multiple cross-sectional images in external storage.

[0092] The motion control unit 2 is connected to the dual beam system 1 and is configured to receive multiple two-dimensional images of multiple cross-sectional surfaces. The motion control unit 2 is configured to determine a three-dimensional (3D) volume image of the inspection volume 160 from the multiple two-dimensional images of the multiple cross-sectional surfaces.

[0093] The wafer inspection system 1000 is configured to receive user information (e.g., CAD information of the semiconductor object of interest, location of the inspection site, or inspection results) for performing a measurement task. The processing engine 201 is configured to calculate the information and display it via the user display 400, and to receive user input via the user interface 401.

[0094] All features, method steps, and advantages described herein with respect to apparatus 100 and steps S1-S6 apply equally to apparatus / system 1000 and steps S2'-S4, and vice versa. Faults can be characterized in the same or substantially the same manner in apparatus or system 100, 1000.

[0095] According to one embodiment, a method is provided for characterizing defects in a scanning electron microscope 100, which is suitable for the analysis and / or processing of samples 8, 10, in particular wafers or lithography masks, using an electron beam 106. The method follows these steps: Step S2' (see Figure 3) involves introducing a trigger event to the scanning electron microscope 100, Step S3 involves detecting the response behavior of the scanning electron microscope 100 to a trigger event, The method includes step S4, which involves comparing the detected response behavior with the expected response behavior in order to characterize the fault.

[0096] Advantageously, this embodiment does not depend on the previous equilibrium state (step S1 of the previous embodiment). Nevertheless, all embodiments and features described above with respect to method steps S1 to S4 apply equally to this method (steps S2' to S4).

[0097] According to one embodiment, step S2 or S2' includes introducing a sequence of trigger events to scanning electron microscopes 40, 100. By using the sequence, faults can be characterized in a more reliable / safer manner.

[0098] According to one embodiment, each trigger event in a trigger event or sequence of trigger events is an event that occurs during the operation of the scanning electron microscopes 40, 100. This may be the normal operation of the scanning electron microscopes. Advantageously, triggers that occur naturally during the operation of the electron microscopes 40, 100 can be used, without requiring "additional" triggers to characterize the system.

[0099] According to one embodiment, the operation preferably includes one or more of the following: A startup phase in which scanning electron microscopes 40 and 100 are activated, which in particular includes opening the column isolation valve 230 (see Figure 2) of the scanning electron microscopes 40 and 100, and / or applying an acceleration voltage to one or more electrodes 104 of the scanning electron microscopes 40 and 100. An analytical step in which samples 8 and 10 are analyzed using a scanning electron microscope 100, and in particular an analytical step including recording one or more images of samples 8 and 10 using scanning electron microscopes 40 and 100. A processing step in which samples 8 and 10 are processed using scanning electron microscopes 40 and 100, and in particular a processing step including depositing material on and / or etching material from samples 8 and 10, and / or milling sample 8 using an ion beam 51, and / or recording one or more images of samples 8 and 10 using scanning electron microscopes 40 and 100, and / or A sample transfer step in which samples 8, 10 are moved into or out of a scanning electron microscope 100 (238), the sample transfer step particularly includes turning off the accelerating voltage applied to one or more electrodes 104 of the scanning electron microscope 40, 100, closing the column isolation valve 230 of the scanning electron microscope 40, 100, and / or opening the three sleases 232 (see Figure 2) in the vacuum housing 110 of the scanning electron microscope 40, 100 to move the samples 8, 10.

[0100] These are examples of stages in which one or more trigger events occur naturally, i.e., stages that occur as part of normal system operation. Therefore, any anomaly detected in step S4 indicates that there may be a problem.

[0101] According to one embodiment, a trigger event or sequence of trigger events includes one or more of the following triggers: A pad 502 comprising a layer preferably made of carbon and tungsten (thus ensuring excellent contrast), and introduction of a gas preferably containing a carbon compound or tungsten precursor for writing position marks 500 on the pad 502 (based on the position marks 500, the progress of milling, particularly the depth, can be determined; the position marks 500 in different images taken with SEM 40 make it easy to determine the progress of milling), (For example, for injecting process gas) To retract and / or extend the gas injection needle 79, Set the sample current (228) to write the position mark 500 on pad 502 (the sample current is preferably greater than 1 or 4 nanoamperes). Setting the irradiation energy (i.e., the energy at which the particles irradiate samples 8 and 10) (the irradiation energy can be, for example, low (e.g., including the range of 500-1000 eV) and / or high (e.g., 15 , 000~30 , (Including the range of 000eV)), For example, at the end of a scan line, beam blanking can be performed during imaging (in this case, for example, a short beam blank can be used using electrode 234 (see Figure 2) to avoid contamination). Beam blanking during FIB processing (in this case, for example, a long beam blank can be used by using coil 234 (see Figure 2) instead of electrodes), Turning off the acceleration voltage during FIB processing. Introducing auxiliary gases during FIB processing (e.g., H2O, O2, N2, and / or XeF2), and / or FIB processing (for example, emission of secondary electrons due to the interaction of FIB processing with a scanning electron microscope 40).

[0102] According to one embodiment, the method further, In the comparison step S4, if an unexpected response behavior is determined, one or more additional trigger events are searched for, and if such additional trigger events are detected, a warning is issued and / or steps S1-S4 or S2'-S4 are repeated and / or the operation of the scanning electron microscope 100 is stopped or terminated.

[0103] Some trigger events are likely to occur simultaneously, making them difficult to isolate and analyze within a running process. Therefore, it may be advantageous to make the methods executable in separate modules. For example, a rough procedure that runs "online" to search for unexpected responses against a list of triggers occurring during the process, issuing a warning (yellow light) indicating that a service call / full procedure is required, or aborting the process (red light). It may also be possible to evaluate partial data as "suspicious" if the system response is abnormal (e.g., increased beam drift in mapping due to blanking for FIB processing).

[0104] For example, in steps S3 and / or S4, the position of the electron beam can be plotted as a function of time for a second imaging method independent of the electron beam (e.g., a focused ion beam) relative to the previously placed alignment mark 500, or the sample position (i.e., the position of sample stages 15, 112) can be determined. Simultaneous imaging with secondary ions and backscattered primary electrons allows for the distinction between beam drift and stage drift (e.g., the absence of a laser interferometer or a defective laser interferometer). However, simultaneous imaging of ions and electrons may form another trigger event.

[0105] Furthermore, it is possible to detect image ray skips and ripples. Image ray skips are very fast, discrete positional changes, in contrast to slow, global image drift. For example, image ray skips can be caused by microarcing (defective insulation distance), which can occur at very high voltages. In addition, deformations of the scanning field (e.g., magnification, trapezoidal / cushioning, nonlinear deformation) can be recorded. This may be due to the charge beneath the scanning system or temperature changes in the scanning system after setting the minimum / maximum magnification.

[0106] [Table 2]

[0107] In a further embodiment, an apparatus is provided. This apparatus is Charged particle beam imaging systems 40 and 100, Detector units 17.2 and 102 for detecting the response behavior of charged particle beam imaging systems 40 and 100 to a trigger event, To characterize the fault, the system includes control units 2 and 120 for comparing the detected response behavior with the expected response behavior.

[0108] According to one embodiment, the apparatus is configured as a mask repair system 100 or a wafer inspection system 1000.

[0109] According to one embodiment, the charged particle beam imaging system includes scanning electron microscopes 40, 100, a FIB column 50, and / or a dual beam system 1.

[0110] In a further embodiment, an apparatus is provided. This apparatus is Charged particle beam imaging systems 40 and 100, The system includes control units 2 and 120 configured to implement the above method.

[0111] The present invention has been described with reference to exemplary embodiments, which can be modified in various ways.

[0112] List of reference symbols 10 Lithography Masks 10' Reference object 100 Processing Layouts 102 electron column 104 Electron source 106 Electron beam 108 Detector Unit 110 Vacuum Housing 112 Sample Stage 114 Vacuum pump 116 Gas supply unit 118 Gas pipelines 120 Control Computer 122 Computer Program Products 200 Anode aperture 202 Aperture diaphragm 204 Beampath Section 206 Capacitors 207 Capacitors 208 Double Capacitor 210 aperture 212 Beampath Section 214 ESB detector 216 SE detector 220 Filter Grid 221 Magnetic Lens 222 Scanning coil 226 Electrostatic Lens 228 Sample Current 230 Column Isolation Valve 232 Threes 234 Beam guiding means 236 particles 238 sample movement 1 Dual-beam device 2. Operation control unit 3 Software Instructions 4.1 HAR Structure 4.2 HAR Structure 4.3 HAR Structure 6.1 Testing Location 6.2 Testing Location 8 wafers 15 Wafer support stand 16 Stage Control Unit 17.1 Secondary electron particle detectors 17.2 In-lens detector 19 Control Unit 21 High-precision position sensor 23 Condition Monitor 25 measurement frames 27 Measurement Frame 29 Deflection Scanner 31 Charged particle beam source 33 Objective lens 40 Scanning imaging system 42 CPB imaging system 43 Intersection 44 Charged particle beam 48 FIB axis 50 FIB columns 51 FIB ion beam 52 Cross section surface 53.i…53.j Cross section surface 55 Wafer surface 79 GIS 81 Contact pins 155 Wafer Stage 160 test volumes 201 Processing Engine 203 Storage 205 User Interface 219 storage 231 Interface Unit 400 user displays 401 User command device 500 position markers 502 pad 1000 wafer inspection system GE angle GFE angle GE angle L.1~LM layer S1-S6 Method Steps T1-T9 Method Steps

Claims

1. A method for determining the presence, type, and / or location of an obstruction that reduces the stability of an electron beam column in a scanning electron microscope (100), wherein the scanning electron microscope (100) is configured to analyze or perform electron beam-induced processing on a sample (8, 10) using an electron beam (106), and the method is as follows: S1) The scanning electron microscope (100) is brought to an equilibrium state in which the electron dose in the beam path of the electron beam column is constant over time (S1), S2) A step (S2) of introducing a trigger event that disrupts the equilibrium state into the scanning electron microscope (100), S3) A step (S3) to detect the response behavior of the scanning electron microscope (100) to the trigger event, S4) Step (S4) to determine the presence, type, and / or location of the specific fault in order to conclude that a particular fault reduces the stability of the electron beam column, by comparing the detected response behavior with the expected response behavior which is the response of the scanning electron microscope (100) to the trigger event during normal operation, and based on the comparison, A method having

2. The method according to claim 1, wherein N images are recorded in step (S1).

3. The method according to claim 2, wherein N is greater than 3.

4. The method according to claim 1 or 2, wherein in step (S1), the position or clarity of the electron beam (106) is recorded as a function of time and compared with a threshold, and the start of step (S2) depends on the comparison.

5. The method according to claim 1 or 2, wherein the response behavior detected in step (S3) is the position, focus, stigmeter, or coma aberration of the electron beam (106) as a function of time.

6. The method according to claim 1 or 2, wherein the trigger event includes a change in sample current, which is an electron current directed toward a reference object, a change in acceleration voltage, or a change in the electron beam cross-section or position of the electron beam (106).

7. Steps (S1) to (S4) are performed for a first trigger event that disrupts the equilibrium state, and are repeated for a second trigger event that disrupts the equilibrium state (S5), wherein the first and second trigger events are selected such that the electron dose at a first location (204) in the beampath of the electron beam (106) has a first value when the first trigger event occurs and a second value different from the first value when the second trigger event occurs, and the electron dose at a second location (212, 218) in the beampath of the electron beam (106) has a first value when the first trigger event occurs and a second value equal to the first value when the second trigger event occurs, and in step (S6) following step (S4), the fault is assigned to the first location (204) depending on the comparison in step (S4) for the first and second trigger events, the method according to claim 1 or 2.

8. (i) The first trigger event includes focusing the electron beam (106) with an anode diaphragm (200) located downstream of the electron source (104) for generating the electron beam (106) or with an aperture diaphragm (202) located downstream of the anode diaphragm (200) in the beam path of the electron beam (106), and the sample current (228), which is the electron current toward the reference object, is collected in a Faraday cup; the second trigger event includes trimming the electron beam (106) using the anode diaphragm or aperture diaphragm (200, 202), and the sample current (228) is similarly collected in the Faraday cup; (ii) The first trigger event includes a change in current in the electron source (104), and the second trigger event includes an increase in the sample current (228) using capacitor excitation. (iii) The first trigger event includes the electron beam (106) passing through the aperture (210), the second trigger event includes an increase in the sample current (228), or (iv) The method according to claim 7, wherein the first trigger event includes completely shielding the electron beam (106) in the aperture (210), and the second trigger event includes collecting the electron beam (106) in a Faraday cup.

9. The method according to claim 1 or 2, wherein steps (S1) to (S4) are performed in a fully automated manner.

10. The method according to claim 1, wherein step (S2) includes introducing a sequence of trigger events that disrupt the equilibrium state to the scanning electron microscope (100).

11. The method according to claim 1, wherein each trigger event in the trigger event or sequence of trigger events is an event that occurs during the operation of the scanning electron microscope (100).

12. The aforementioned operation includes, A startup step in which the scanning electron microscope (100) is activated, which includes opening the column isolation valve (230) of the scanning electron microscope (100) or applying an acceleration voltage to one or more electrodes (104) of the scanning electron microscope (100), An analytical step in which the samples (8, 10) are analyzed using the scanning electron microscope (100), the analytical step comprising recording one or more images of the samples (8, 10) using the scanning electron microscope (100), A processing step in which the sample (8, 10) is subjected to electron beam induced treatment using the scanning electron microscope (100), the processing step including depositing material on the sample (8, 10) or etching material from the sample (8, 10), or milling the sample (8) using an ion beam (51), or recording one or more images of the sample (8, 10) using the scanning electron microscope (100), or A sample transfer step in which the samples (8, 10) are moved into or out of the scanning electron microscope (100) (238), the sample transfer step including turning off the acceleration voltage applied to one or more electrodes (104) of the scanning electron microscope (100), closing the column isolation valve (230) of the scanning electron microscope (100), or opening the thread (232) in the vacuum housing (110) of the scanning electron microscope (100) to move the samples (8, 10), The method according to claim 11, comprising one or more of the above.

13. The trigger event or sequence of trigger events includes the following triggers: In the scanning electron microscope (100), a pad (502) located near the work area where the electron beam-induced processing of the samples (8, 10) is performed, and the introduction of a gas for writing a position mark (500) on the pad (502), A gas injection needle (79) for locally introducing gas toward the pad (502) is retracted or extended. Setting a sample current (228), which is an electron current directed toward a reference object in order to write a position mark (500) on a pad (502), Setting the irradiation energy such that the irradiation energy is within the range of 500 to 1000 eV, or within the range of 15,000 to 30,000 eV. At the end of the scan line, beam blanking is performed during imaging. Performing beam blanking during FIB processing, Turning off the acceleration voltage during FIB processing. During FIB treatment, introduce an auxiliary gas such as H2O, O2, N2, or XeF2, or FIB processing is performed by an FIB column (50), and the FIB processing is the emission of secondary electrons due to the interaction between the FIB column (50) and the scanning electron microscope (100). The method according to claim 1, comprising one or more of the following.

14. The method according to claim 1, further comprising: if an unexpected response behavior is determined in the comparison step (S4), if one or more additional trigger events are introduced to the scanning electron microscope (100), a warning is issued, or steps (S1) to (S4) are repeated, or the operation of the scanning electron microscope (100) is stopped.

15. A method for determining the presence, type, and / or location of a fault in a scanning electron microscope (100), wherein the scanning electron microscope (100) is configured to perform analysis or electron beam induction processing on a sample (8, 10) using an electron beam (106), and the method is: S1) The scanning electron microscope (100) is brought to an equilibrium state in which the electron dose in the beam path of the electron beam column is constant over time (S1), S2) A step (S2) of introducing a trigger event that disrupts the equilibrium state into the scanning electron microscope (100), S3) A step (S3) to detect the response behavior of the scanning electron microscope (100) to the trigger event, S4) Step (S4) to determine the presence, type, and / or location of the specific fault by comparing the detected response behavior with the expected response behavior, which is the response of the scanning electron microscope (100) to the trigger event during normal operation, in order to conclude that a specific fault exists. It has, Steps (S1) to (S4) are performed for a first trigger event that disrupts the equilibrium state and are repeated for a second trigger event that disrupts the equilibrium state (S5), wherein the first and second trigger events are selected such that the electron dose at a first location (204) in the beampath of the electron beam (106) has a first value when the first trigger event occurs and a second value different from the first value when the second trigger event occurs, and the electron dose at a second location (212, 218) in the beampath of the electron beam (106) has a first value when the first trigger event occurs and a second value equal to the first value when the second trigger event occurs, and in step (S6) following step (S4), the fault is assigned to the first location (204), depending on the comparison in step (S4) for the first and second trigger events.

16. A method for determining the presence, type, and / or location of a fault in a scanning electron microscope (100), wherein the scanning electron microscope (100) is configured to perform analysis or electron beam induction processing on a sample (8, 10) using an electron beam (106), and the method is: S1) The scanning electron microscope (100) is brought to an equilibrium state in which the electron dose in the beam path of the electron beam column is constant over time (S1), S2) A step (S2) of introducing a trigger event that disrupts the equilibrium state into the scanning electron microscope (100), S3) A step (S3) to detect the response behavior of the scanning electron microscope (100) to the trigger event, S4) Step (S4) to determine the presence, type, and / or location of the specific fault by comparing the detected response behavior with the expected response behavior, which is the response of the scanning electron microscope (100) to the trigger event during normal operation, in order to conclude that a specific fault exists. It has, Each trigger event in the trigger event or sequence of trigger events is an event that occurs during the operation of the scanning electron microscope (100). The aforementioned operation includes, A startup step in which the scanning electron microscope (100) is activated, which includes opening the column isolation valve (230) of the scanning electron microscope (100) or applying an acceleration voltage to one or more electrodes (104) of the scanning electron microscope (100), An analytical step in which the samples (8, 10) are analyzed using the scanning electron microscope (100), the analytical step comprising recording one or more images of the samples (8, 10) using the scanning electron microscope (100), A processing step in which the sample (8, 10) is subjected to electron beam induced treatment using the scanning electron microscope (100), the processing step including depositing material on the sample (8, 10) or etching material from the sample (8, 10), or milling the sample (8) using an ion beam (51), or recording one or more images of the sample (8, 10) using the scanning electron microscope (100), or A sample transfer step in which the samples (8, 10) are moved into or out of the scanning electron microscope (100) (238), the sample transfer step including turning off the acceleration voltage applied to one or more electrodes (104) of the scanning electron microscope (100), closing the column isolation valve (230) of the scanning electron microscope (100), or opening the thread (232) in the vacuum housing (110) of the scanning electron microscope (100) to move the samples (8, 10), A method that includes one or more of the following.

17. A charged particle beam imaging system (40), A detector unit (17.2) for detecting the response behavior of the charged particle beam imaging system (40) to a trigger event that disrupts the equilibrium state in which the electron dose in the beam path of the electron beam column remains constant over time, A control unit (2, 120) for determining the presence, type, and / or location of the specific fault in order to conclude a particular fault that reduces the stability of the electron beam column, by comparing the detected response behavior with the expected response behavior, which is the response to the trigger event during normal operation of the scanning electron microscope (100), and based on the comparison, A device equipped with the following features.

18. The apparatus according to claim 17, configured as a mask repair system (100) or a wafer inspection system (1000).

19. The apparatus according to claim 17 or 18, wherein the charged particle beam imaging system (40) includes a dual beam system (1), and the dual beam system (1) includes a scanning electron microscope (100) and a FIB column (50).

20. A charged particle beam imaging system (40), A control unit (2, 120) configured to carry out the method according to claim 1, A device equipped with the following features.

21. A computer program (3, 122) including commands, wherein when the computer program is executed by a computer, it causes the computer to perform the method according to claim 1.

Images