Method and device for positioning a microscopic sample with the aid of a two-dimensional position table

Abstract

A method for positioning a sample in a microscope system, wherein a region of interest (ROI) of the sample is observed and / or processed by the microscope system, and the microscope system comprises: an optical axis; a movable sample stage for receiving the sample; a storage device storing a data record describing the position of the sample; a control device capable of controlling the movement of the sample stage with the aid of the stored data record. The method comprises the following steps: a) keeping the sample region (ROI) at a first position; b) storing a first data record, by which the first position is described, wherein the first position is defined as an independent position; c) storing a second data record, by which the second position is described, wherein the second position is linked to the independent position; d) calling one of the stored data records so that the sample stage is moved so that the sample region remains at the position described by the called data record.

Description

Field of the Invention

[0001] The present invention relates to a method for positioning a microscopic sample in a sample chamber of a microscope system, such as an optical microscope or an electron microscope. Background Art

[0002] Generally, the area of the sample to be examined is so large that the region of interest (ROI) of the sample cannot be completely arranged within the field of view of the microscope system for examination. Therefore, the sample must be shifted in order to image or process the entire sample. In addition, there are cases where multiple regions of interest (ROIs) of the sample exist on the same sample. In such cases, the sample must also be shifted so that the regions of interest (ROIs) of the sample can be successively brought into the field of view of the microscope system in order to be able to image or process the ROIs. In addition, when preparing a microscopic sample, it is often necessary to keep the region of interest of the sample at various precisely defined positions relative to the optical axis of the microscope system. Therefore, navigation (i.e., the accurate positioning and retrieval of the region of interest of the sample) plays an important role in microscopy and structuring problems.

[0003] In the case of a microscope system whose operation is based on a charged particle beam, such as an electron microscope or an ion beam microscope, the sample is usually assembled on a displaceable sample stage. For example, this can be a five-axis stage by means of which the sample can be moved in the x and y spatial directions in such a way that it remains within the field of view of the microscope system. In addition, the sample, in particular the region of interest (ROI), is held at a certain distance (z-height) from the objective lens such that the optical axis of the particle beam device extends substantially at right angles to the surface of the sample and can be focused on the region of interest (ROI).

[0004] Five-axis stages are commonly used in scanning electron microscopes (SEM), ion beam microscopes or dual-beam devices. A dual-beam device is a combined device that includes both an electron beam column and an ion beam column (focused ion beam, FIB). Dual-beam devices are typically used to observe microscopic samples with the electron beam column and to process these microscopic samples with the ion beam column. For example, cross-sections can be fabricated or TEM foils can be prepared in a dual-beam device. During such sample preparation, the sample must usually be held at a plurality of different positions, i.e., at different locations and spatial orientations, in particular in such a way that on the one hand it can be imaged with the electron beam column and on the other hand it can be processed with the focused ion beam (FIB).

[0005] Position lists, two-dimensional images or CAD data are usually used to position the sample; however, this is associated with a large amount of work and documentation expenditure by the user.

[0006] Accordingly, it is desirable to simplify the capture and use of location data and automate it at least in part. Additionally, it would be advantageous to process the data in a user-friendly manner such that the user's effort and documentation expenditure are kept as low as possible and incorrect or inapplicable location data is avoided from being entered.

[0007] This is provided by the method according to the invention. Additionally, the positioning method described below can be implemented as an intelligent method, i.e., as a self-learning method that monitors the input of data and provides options for improving the positioning accuracy of the sample stage.

[0008] Brief description of the related prior art

[0009] As is well known, in order to position a sample during sample preparation, a simple location list editable by the user is used, which lists the various locations where the sample can be placed. Typically, the sample is first manually moved to the desired location so that these locations can then be stored in the location list. Subsequently, the stored locations can then be called to move the sample back to the relevant location. The disadvantage is that this requires a large amount of effort as all locations have to be manually approached and individually recorded by the user. Additionally, managing and processing long lists (which can be regarded as one-dimensional tables) can be very confusing.

[0010] It is also known to use graphical aids such as two-dimensional overview images or CAD layout data for navigation purposes. Typically, the goal is to retrieve the region of interest (ROI) of the sample in two dimensions (x, y) or three dimensions (x, y, z). However, even in these methods, especially if changes in three-dimensional coordinates or spatial orientation (e.g., tilting and rotation of the sample) are to be taken into account, the user may find it difficult to position and record the required data by themselves. Summary of the invention

[0011] The object of the present invention is to provide a method by which a sample to be examined can be positioned in a particle beam apparatus in a user-friendly manner and by which approaching a predetermined sample position can be made partially or fully automated.

[0012] According to the present invention, these objects are achieved by a method having the features described below.

[0013] A method for positioning a sample in a microscope system, wherein an area of interest (ROI) on the sample is observed and / or processed using the microscope system, and the microscope system comprises:

[0014] - an optical system or a particle-optical system that defines an optical axis,

[0015] - A movable sample stage for receiving a sample, by means of which the sample can be held in a first position and a second position relative to the optical axis of the microscope system;

[0016] - A storage device for storing data records describing these positions;

[0017] - A control device that controls the movement of the sample stage by means of the stored data records;

[0018] And the method includes the following steps:

[0019] a) Holding a sample region (ROI) in the first position;

[0020] b) Storing a first data record that describes the first position, where the first position is defined as an independent position;

[0021] c) Storing a second data record that describes the second position, where the second position is linked to the independent position;

[0022] d) Invoking one of the stored data records such that the sample stage moves so that the sample region is held in the position described by the invoked data record.

[0023] Advantageous configurations are specified below.

[0024] Preferably, the linking is implemented by calculating the second position with a computational operation.

[0025] Preferably, the linking is implemented by manually approaching the second position.

[0026] Preferably, the data records can be presented in a two-dimensional table.

[0027] Preferably, the data records are saved in such a way that the relationship between the data records is represented by the arrangement in the two-dimensional table.

[0028] Preferably, method steps a) to d) are repeated for a second sample region of interest (ROI), and the data records of the second sample region of interest (ROI) are also presented in the two-dimensional table.

[0029] Preferably, the data records are editable.

[0030] Preferably, at least one rule is recorded that defines the management logic between two sample positions such that the sample can only be positioned in those sample positions permitted by the rule.

[0031] Preferably, the sample stage includes at least two axes, and the movement of the sample stage is defined by the order, speed, and degree of movement of these axes, and wherein at least one rule is recorded, and the at least one rule specifies the order, speed, and degree by which these axes are to be moved in order to position the sample.

[0032] Preferably, the accuracy of positioning the region of interest (ROI) of the sample is improved by storing the corrected position when correcting the sample position.

[0033] Preferably, the two-dimensional table is implemented as a graphical user interface.

[0034] Preferably, a charged particle beam is generated in the microscope system.

[0035] Preferably, the microscope system includes an electron beam column.

[0036] Preferably, the microscope system includes an ion beam column.

[0037] Furthermore, the present invention relates to a particle beam device described below, which is configured to perform the method according to the present invention, and to a computer program described below, which causes the particle beam device to perform the positioning method.

[0038] A microscope system, comprising:

[0039] - an optical system or a particle-optical system, which system defines an optical axis,

[0040] - a movable sample stage for receiving a sample, by means of which the sample can be held in a first position and a second position relative to the optical axis of the microscope system, wherein the first position can be described by a first data record and the second position can be described by a second data record;

[0041] - a storage device for storing the data records, wherein the data records can be stored in a two-dimensional table;

[0042] - a control device, which can control the movement of the sample stage by means of the stored data records;

[0043] wherein the microscope system is configured to perform a method for positioning the sample, the method comprising the following steps:

[0044] A) Holding the sample region (ROI) in the first position;

[0045] B) Storing a first data record, which describes the first position, wherein the first position is defined as an independent position;

[0046] C) Store a second data record that describes the second position, wherein the second position is linked to the independent position;

[0047] D) Call one of the stored data records so that the sample stage moves to keep the sample area at the position described by the called data record.

[0048] A microscope system, comprising:

[0049] - An optical system or a particle-optical system that defines an optical axis,

[0050] - A movable sample stage for receiving a sample, by means of which a first area of the sample can be brought to different locations and spatial orientations relative to the optical axis of the microscope system, and by means of which a second area of the sample can be brought to different locations and spatial orientations relative to the optical axis of the microscope system, wherein the different locations and spatial orientations of the first area and the second area of the sample can be described by different data records respectively;

[0051] - A storage device for storing data records;

[0052] - A control device that controls the movement of the sample stage by means of the data records stored in the storage device;

[0053] - A user interface having a display device on which information items can be displayed in the fields of a two-dimensional table, wherein the fields in the first row or column of the two-dimensional table are assigned to the first area of the sample, and the fields in the second row or column parallel to the first row or column are assigned to the second area of the sample;

[0054] And wherein the data records stored in the data storage device are assigned to the fields of the two-dimensional table, and the data records correspond to different locations and / or spatial orientations of the sample relative to the optical axis,

[0055] Wherein the data records assigned to the fields of the first row or column,

[0056] Correspond to different locations and / or spatial orientations of the first area of the sample relative to the optical axis;

[0057] And the data records assigned to the fields of the second row or column,

[0058] different locations and / or spatial orientations of the second region corresponding to the sample relative to the optical axis;

[0059] and wherein the control device is configured to move the sample stage relative to the optical axis when starting the user interface at a selected field of the two-dimensional table, the movement proceeding until the first region or the second region of the sample assigned to the selected field assumes the location and / or spatial orientation relative to the optical axis described in the data record assigned to the selected field.

[0060] Preferably, the user interface is configured to:

[0061] assign commands to the stored data records assigned to the fields of the two-dimensional table assigned to the first region of the sample;

[0062] and the user interface is further configured to assign commands to the stored data records assigned to the fields of the two-dimensional table assigned to the second region of the sample,

[0063] wherein the control device is configured to calculate and assign an associated data record for the field assigned to the second region of the sample, the associated data record corresponding to the command assigned to the field,

[0064] wherein, when calculating the data record, the stored data records assigned to the second region of the sample are considered in different fields, the other fields are assigned to the second region of the sample, and wherein the stored data records assigned to the first region of the sample are considered when calculating the data record, the stored data records being assigned to fields assigned the same command as the field for which the data record is to be calculated and assigned.

[0065] Preferably, the user interface is configured to assign commands from a list of commands to the fields of the two-dimensional table assigned to the first region of the sample and / or to the fields of the two-dimensional table assigned to the second region of the sample, and wherein the control device is configured to calculate the associated data record and assign it to the selected field, the associated data record corresponding to the command assigned to the selected field, wherein the stored data records are considered when calculating the data record, the stored data records being assigned to another field assigned to the same region of the sample.

[0066] A computer program comprising a sequence of control commands that cause a microscope system to perform the method for positioning a sample as described above.

[0067] The present invention is based on the following finding: During sample preparation, the sample is shifted to various sample positions, which are related to each other. The corresponding relationship between two positions can be generated due to spatial conditions (sample and / or device geometry) or can be arbitrarily assigned by the user. Usually, the sample positions are successively approached in a defined order, where some positions may be approached multiple times.

[0068] In any case, the knowledge of the mutual dependence of the individual sample positions can be used to improve the method of sample positioning.

[0069] The sample position (also abbreviated as "position") includes the location and spatial orientation of the sample. Here, the term location means the positioning of the sample in three-dimensional space, which can be described by specifying x, y, and z coordinates. The spatial orientation is understood to represent the alignment of the sample. Usually, the spatial orientation is specified relative to one optical axis of the microscope system. The geometric configuration of the sample and / or the desired processing steps mean that the sample must maintain a specific alignment relative to the (multiple) optical axes of the microscope system. Usually, the spatial orientation of the sample is modified by rotating the sample around the tilt axis and / or the rotation axis. Here, the tilt axis of the sample usually has to be aligned in such a way that the sample is tilted according to the requirements of the respective processing geometry.

[0070] The term positioning should be understood to mean that the sample is moved to the sample position. Here, the route by which the sample is moved from the first position to the second position also plays a role in some cases. The route should be understood as the exact displacement path, i.e., the sequence, speed, and degree of translational movement (displacement step) and rotational movement (tilt, rotation).

[0071] The movement of the sample to various positions is usually accomplished by a displaceable sample stage. The sample stage usually includes at least translational movement elements by means of which it can be moved in the x and y directions and usually also in the z direction. Here, the aforementioned translational axes are oriented at right angles to each other in each case. The sample stage usually also includes rotational movement elements having, for example, a first rotation axis (R) around which the sample stage is rotatably arranged. It is also conceivable that the stage further has a second rotation axis (T) around which the stage can rotate and which is arranged at right angles to the first rotation axis. The second rotation axis is also referred to as the tilt axis (T). If such a five-axis stage is used, the sample to be examined can thus be displaced in the three spatial directions x, y, and z to change the location of the sample. Moreover, by means of rotation and / or tilt of the sample, the spatial orientation of the sample can be changed. It is also conceivable to implement the sample stage as a six-axis stage (so-called superalignment stage), i.e., as a five-axis stage having an additional axis commonly referred to as the M axis.

[0072] The control device controls the movement of the sample stage. Advantageously, this is implemented in a computer-based manner by the interaction of the control device with the storage device. The desired position of the region of interest of the sample can be described by data recording and stored with the aid of the storage device. To approach a certain sample position, the relevant data record is called from the storage device, such that the control device moves the sample stage together with the sample to the position described in the data record.

[0073] The data record should be understood to mean data assigned to a sample position and including information (such as the x, y and z coordinates and the tilt angle of a certain sample) that can fully characterize the sample position.

[0074] According to the invention, the data records describing the respective sample positions are displayed in a two-dimensional table, i.e., in a matrix structure. Additional information can be conveyed by the arrangement within the matrix. For example, the following information can be conveyed: all data entries in a column apply to the same sample. In addition, the following information can be linked: all data entries in a specific row describe the same spatial orientation of the corresponding sample relative to the optical axis of the microscope system. In other words: the relationship between the data records is represented by using a two-dimensional table. This facilitates partial or complete automation of sample positioning.

[0075] Starting from freely selectable sample positions defined as independent, dependent positions can be pre-calculated or manually assigned. Here, the relationship between the independent position and the dependent position can be described, for example, by a fixed value or by a mathematical function.

[0076] It may be particularly advantageous to store the relationship between the sample positions as relative links, such that a change in a position necessarily results in a change in the other linked positions.

[0077] It is also conceivable to confirm the sample position by logical analogical conclusions. Starting from the sample position of the first region of interest of the sample, the corresponding position of the second sample region can be calculated in a similar manner.

[0078] Thus, by all the sample positions of the initially stored first region of interest (ROI) of the sample, sample positioning can be standardized during preparation. Then, the sample positions or sample alignments of other regions of interest (ROI) of the sample can be derived in a similar manner from the stored data. This is advantageous because the user only needs to manually enter a few sample positions and can calculate multiple sample positions with the aid of a computer-based control device.

[0079] In addition, management logic can be defined, which determines in the form of rules whether certain locations and spatial orientations should be allowed as sample positions.

[0080] It is also conceivable that predetermined commands are provided in a command list from which the predetermined commands can be selected and assigned to data records and / or fields in a two-dimensional table. A sample stage can be moved with the aid of the commands such that a region of interest of the sample is moved from a first sample position to a second sample position. Description of the Drawings

[0081] Exemplary embodiments of the invention will be explained below based on the drawings. For the purpose of explaining the components, reference is also made to the overall description before and after, respectively.

[0082] Figure 1 A situation in a particle beam apparatus configured to perform a positioning method according to an exemplary embodiment is shown.

[0083] Figure 2 A flowchart of a first exemplary embodiment of a method according to the invention is shown.

[0084] Figure 3a A two-dimensional position table is shown in an exemplary manner.

[0085] Figure 3b An alternative two-dimensional position table is shown in an exemplary manner.

[0086] Figure 4 A flowchart of a second exemplary embodiment of a method according to the invention is shown.

[0087] Figure 5 A specific manifestation of a two-dimensional position table is shown.

[0088] Figure 6 A particle beam apparatus is shown with which a positioning method can be performed.

[0089] Figure 7 An example of a two-dimensional position table implemented as a graphical user interface is shown. Detailed Description of the Invention

[0090] Figure 1 and Figure 2 relates to a first exemplary embodiment of a positioning method according to the invention that can be used for TEM lamella preparation.

[0091] TEM lamellae are microscopic samples required for examination in a transmission electron microscope (TEM). In at least one part, the TEM lamellae are so thin that they can be penetrated by electrons such that the transmitted electrons can be detected and used for image generation. Usually, TEM lamellae are prepared from the entire sample material (i.e., the sample block). In a so-called lift-off process, the TEM lamellae are separated from the sample block and transferred to a transfer holder.

[0092] Figure 1Schematically shows a situation in the sample chamber of a dual-beam device, where the sample block 6 and the transfer holder 2 are positioned during the preparation of a TEM lamella.

[0093] The sample block 6 including a spatial region to be prepared as a TEM lamella is assembled on a sample holder 5. The transfer holder 2 is held on another sample holder 3. Both of these sample holders 3, 5 are held on a displaceable sample stage 4, which is preferably implemented as a five-axis stage.

[0094] The transfer holder 2 is used to receive the TEM lamella separated from the sample block 6 and to hold the TEM lamella available for further use. For example, the transfer holder 2 can be implemented as a lift grid.

[0095] The sample stage 4 on which the above elements are assembled is located in the sample chamber of the dual-beam device, which has an electron beam column 1 and an ion beam column 7. In addition, the dual-beam device includes a storage device (not shown) and a control device (not shown). The control device can be used to move the sample stage 4 to allow the sample stage 4 and the elements assembled thereon to be displaced to a predetermined position. Thus, by moving the sample stage 4, the sample block 6 and the transfer holder 2 can be held at different positions relative to the optical axes 8, 9 of the particle beam device.

[0096] Figure 2 Shows a flow chart of a first exemplary embodiment of a positioning method according to the present invention. Here, in step S1, the sample stage of the dual-beam device is loaded with a sample block and a transfer holder, from which a first TEM lamella is to be obtained. Conventionally, the sample stage includes a plurality of container devices for sample holders. The sample holder carrying the sample block is assembled on one of the container devices. The transfer holder (which is also a sample holder in principle) is assembled on a second container device, and the first TEM lamella is intended to be transferred to the transfer holder after being separated from the sample block.

[0097] In step S2, the sample block is imaged by means of the scanning electron microscope function of the dual-beam device. For this purpose, the sample block is positioned by means of the control device such that the sample block is aligned substantially at right angles to the optical axis of the electron beam column. This means that the electron beam impinges on the sample surface at approximately a right angle. Here, it is advantageous to select the working distance (z-height) in a manner that results in good imaging characteristics.

[0098] Then, a region of interest (ROI) of the sample intended for the preparation of the first TEM lamella is selected based on the image of the sample (step S3). It may be necessary to displace the sample in the x and y directions until the region of interest (ROI) of the sample is placed under the objective of the electron beam column such that the region of interest (ROI) is located in the field of view of the electron beam column as desired.

[0099] In the next step S4, the current position of the first region of interest (ROI) is stored. Here, a first data record is stored which describes the location and the spatial orientation of the first region of interest (ROI). The data record with the required information can be presented in a two-dimensional table with the aid of a storage device.

[0100] The sample position of the first region of interest (ROI) stored in step S4 is advantageously defined as an independent position and stored as such. The independent position can be freely chosen. During the course of the method, other sample positions can then be assigned to this independent position. In other words: The other positions are linked to this independent position such that the assigned positions are considered to be subordinate to this independent position. Advantageously, the data record is provided with a unique and characterizing label, such as "facing the SEM", such that further processing is made easier.

[0101] In the next step S5, the transfer holder is imaged by means of a scanning electron microscope. For this purpose, the sample stage is moved in such a way that the transfer holder is positioned below the objective of the electron beam column.

[0102] In step S6, a first sample receiving region is selected on the basis of the SEM image, specifically the region on the transfer holder onto which the first TEM lamella is to be transferred in a subsequent lift.

[0103] The position of the first receiving region is linked to the "facing the SEM" first sample position and stored (step S7). Advantageously, this position is saved together with a suitable label (such as "attached to grid finger") and can be presented in a two-dimensional table. Particularly advantageously, this is achieved in such a way that the link becomes recognizable from the arrangement in the table. For example, this is the case if the data records linked to one another are saved in different rows of the same column (as Figure 3a shown), where all fields in this column are associated with the first TEM lamella and the entries in these fields represent the various sample positions of the first TEM lamella.

[0104] If desired, even other sample positions can now be defined and stored. For this purpose, the desired position can be approached and stored manually. Alternatively, other desired sample positions can be determined and stored by a computational operation - starting from the independent position to which they are linked.

[0105] If it is intended to process a second TEM lamella, the method steps S2 to S8 are repeated for the second TEM lamella.

[0106] Finally, in step S9, the sample positions stored in the data record are called, such that the sample stage is moved by the interaction of the storage device and the control device. The movement of the sample stage is achieved in such a way that the sample area is shifted to and held at the position described by the called data record. Thus, that is to say, the sample area assumes a predetermined location and a predetermined spatial orientation relative to the microscope system, preferably relative to the optical axis of the microscope system.

[0107] Thus, the method according to the invention allows the sample area located at any position to be shifted such that the sample area is moved to another previously determined position.

[0108] Figure 3a and Figure 3b shows the appearance of a two-dimensional table in which the data record is displayed. Figure 3a It shows that the fields 33, 34, 35, 36 of the table are arranged in columns 31, 32 and rows 37, 38. All the fields in column 31 are assigned to a certain sample, for example the first TEM slice (slice 1). The data records of the respective positions of this sample are stored in rows 37, 38 of column 31. This means that the data records of all the sample positions that the sample is intended to assume during the preparation of the first TEM slice are stored in column 31.

[0109] Of course, it is also conceivable to reverse the dimensions of the table, as Figure 3b shown. Here, the data of a certain sample (for example, slice 1) are arranged in row 39. The sample positions belonging to this sample are stored in the respective columns 40, 41.

[0110] Figure 3a and Figure 3b The common point of the two variants of

[0111] is that the data record is presented in a matrix structure. It is particularly advantageous here that the relationships between the data records are represented, i.e., reproduced, by the arrangement in the two-dimensional table. Thus, in contrast to a position list, laborious tagging can be dispensed with. The relationships between the data entries in the respective fields 33, 34, 35, 36 can be assigned manually or generated by calculation.

[0112] In the exemplary embodiments described above and below, it is also conceivable in principle to store the original data, i.e., the data on the location and spatial orientation, in the data records describing the independent sample positions. The storage is carried out together with the information on the relationships, and the subordinate positions are linked to the independent positions through the relationships. Thus, that is to say, the original data are stored by the management logic. This is advantageous because only a small amount of data needs to be stored. The calculation of the subordinate sample positions to be approached is only carried out when the data are read, i.e., when the sample is to be moved to a certain sample position. Thus, the exact data on the location and spatial orientation of the subordinate sample positions are only determined "instantly".

[0112] In the context ofFigure 4 In another exemplary embodiment to be explained, the method according to the invention is used to navigate a sample in a sample chamber of a dual-beam device when preparing a sample cross-section. Preparing a sample cross-section can be part of TEM lamella preparation.

[0113] The sample cross-section is a polished surface extending at a right angle to the sample surface. To produce the cross-section, the sample is typically initially imaged with a scanning electron microscope, where the area on the sample intended to produce the cross-section is set.

[0114] For this purpose, the sample is held below the objective lens of the electron-optical column such that the sample surface is aligned approximately at a right angle to the optical axis of the electron-optical column. For example, this sample position is labeled "facing SEM". Then, the sample material is ablated (milled) using a focused ion beam until the cross-section area is exposed. In this processing step, the sample must be held below the objective lens of the ion-optical column, specifically such that the sample surface is aligned approximately at a right angle to the optical axis of the ion-optical column (sample position: "facing FIB").

[0115] Advantageously, the sample is also rotated during this process such that the tilt axis of the sample is aligned parallel to the longitudinal extent of the cross-section (sample position: "rotated from facing FIB"). In principle (depending on the sample geometry and the geometry of the microscope system used), the processing geometry may require the sample to be rotated in some way in order to be able to perform the required processing steps.

[0116] To prevent collisions between the sample and the microscope system, it is generally desirable to hold the sample at an increased distance, for example, at a distance increased by 1 mm from the objective lens of the particle-optical device. For this purpose, other positions that meet these criteria can be defined (sample position: "facing FIB - 1 mm").

[0117] As described above, the sample material is ablated using a focused ion beam to produce the cross-section. However, due to the shape of the beam profile of the focused ion beam, the resulting cross-section mostly does not extend precisely at a right angle to the sample surface. Therefore (depending on the conditions), the sample is still tilted in a slightly more or less pronounced manner such that the ion beam may be post-processed at a changed angle of incidence (sample position: "rotated to FIB and over-tilted"). This allows a cross-section area to be produced that is aligned at a right angle to the sample surface. Finally, the sample is placed in a position where the cross-section can be imaged in a scanning electron microscope. Here, it is advantageous to tilt the sample at an angle of 60° between the optical axis of the electron-optical column and the cross-section (sample position: "facing SEM at 60°").

[0118] Thus, during cross-section preparation, the sample is successively moved to various different positions relative to the optical axis of the electron-optical column and the optical axis of the ion-optical column and held in these positions. Due to the geometric conditions of the dual-beam device, there is a logical relationship between the individual positions in the position sequence in each case, which can be formulated mathematically. For example, the two beam columns are arranged at a specific angle α relative to each other. Thus, starting from the first sample position defined as an independent position, additional positions can be determined by means of computational operations and linked to the first sample position.

[0119] For example, the "facing SEM" position (where the sample is held in the focal plane at right angles to the SEM column optical axis without tilt) can be selected as the independent position. As Figure 4 shown, in step S41 the sample is first brought into this position so that it can be imaged with the SEM. Advantageously, the positioning is carried out while generating the SEM record, so that the exact position of the sample can be set and monitored.

[0120] Then (step S42), the position found in step S1 is stored as the independent position. It may be particularly user-friendly if the positions are presented in a two-dimensional position table (such as Figure 5 ).

[0121] In step S43, the dependent positions are calculated and stored, and they are saved row by row in the two-dimensional table, for example. Here, the "facing FIB" position can be calculated as the dependent position without having to approach this position manually. The electron-optical column and the ion-optical column are arranged at a fixed angle α relative to each other, for example at an angle of 54°. To move the sample from the "facing SEM" sample position to the "facing FIB" position, the sample must be rotated by the angle α about the tilt axis. If the site coordinates and spatial coordinates of the "facing SEM" position are known and stored, the site coordinates and spatial coordinates of the "facing FIB" position can be calculated.

[0122] Thus, the resulting sample positions required for the corresponding sample preparation can be calculated from a freely chosen position. Here, in principle, any sample position in the position sequence can be set as the independent position, since the linking is usually reversible.

[0123] In some cases, it may be necessary or desirable to rotate the sample before processing. Here, it has been found to be particularly advantageous to overlay the processing object (coating) onto the SEM image of the sample with the aid of the microscope operating software and to determine the required rotation angle based on this presentation.

[0124] In step S44, the stored positions are called up so that the sample is shifted to the previously set location and spatial orientation.

[0125] Figure 5A two-dimensional position table with sample positions of the second embodiment is shown in an exemplary manner. Each sample position is saved row by row in the table. If multiple cross-sections are to be generated, the table can be designed with multiple columns 51, 52, where the definitions and rules of the respective fields in the first column can be adopted in a similar manner in the fields of the other columns.

[0126] It is particularly advantageous if the data records in the two-dimensional table are editable. Thus, rules can be recorded, which simplifies sample positioning and makes it more reliable. For example, it can be recorded that only approaching those sample positions that are manually defined by the user or can be fully calculated is allowed. It is also conceivable that the user enters a safety margin between the sample and the objective lens by defining a rule. For example, this is implemented by increasing the distance between the sample and the objective lens in the z direction by 1 mm. In addition, it is conceivable to formulate and store rules for the relationships between the individual rows or columns.

[0127] In addition, it is possible to avoid storing clearly incorrect positions, for example, by preventing positions that are at right angles below the objective lens of the electron-optical column from being stored as "facing the FIB". This can avoid confusion and reduce the risk of damage when moving the sample.

[0128] In addition, the route along which the sample stage is shifted to move the region of interest (ROI) of the sample to a specific position can be set in the form of a rule. That is, the shift path is set. For example, this is achieved by defining which stage axes are to be moved and to what extent and in what order the movements are to be made.

[0129] It is also conceivable to formulate rules that define the relationship between the sample position and the operating parameters of the particle beam device (such as the set beam current of the particle beam).

[0130] Finally, rules can also be recorded in a context-dependent manner such that these rules are applied according to very specific processing steps. For example, if approaching a position for a polishing step at an excessive tilt, the rotation of the sample must be correctly selected. However, if approaching the same position for recording a reference image, the rotation can be ignored.

[0131] Moreover, a correction option can be provided by means of which the positioning accuracy can be improved. Since the shift accuracy of the sample stage is limited, it is generally desirable for the user to be able to check the approached positions and manually correct these positions if necessary. Thus, it can be provided that after such a manual correction, the previously stored position is overwritten with the corrected sample position. This can be implemented automatically, for example, triggered by the start of a grinding process or the start of a deposition process. It is also conceivable to perform correction of the positioning by means of automatic drift correction. In this case, the previously stored position can also be overwritten with the corrected sample position.

[0132] Figure 7 shows a particularly advantageous embodiment in which the two-dimensional position table is implemented as a graphical user interface 100. Here, it is conceivable that operations are implemented by buttons 101, 102, 103, 104, 105, by means of which the user can execute commands such as "generate data record (set)" 101, "store data record (save)" 103, "process data record (edit)" 105, "approach sample position (go to)" 102, and "delete data record (delete)" 104. Other buttons can be provided. Particularly advantageously, a dialog box in which the user can edit the data record is opened when the "generate data record (set)" 101 and / or "process data record (edit)" 105 buttons are activated. For example, the relationship between the rows of the two-dimensional table can be specified in the setting or editing dialog box. For example, Figure 5 the relationship between row B and row C in can be: z(C) = z(B) - 1 mm to ensure an increase in the distance from the particle beam column by 1 mm. In addition, other conditions can be specified in the dialog box, such as Figure 5 the conditions for row A and row B in. In this example, this could be: if the angle α between the beam columns is 54°, then according to T = 54°, B = A + calculated central inclination.

[0133] Various embodiments of the method according to the invention can be carried out, for example, using a dual-beam device (FIB-SEM combination device); Figure 6 shows a dual-beam device 61, which includes two particle beam columns, specifically an electron beam column 63 for generating an electron beam and an ion beam column 79 for generating a focused ion beam. Both particle beams are guided to a processing position on the sample 74, which is usually located at the coincidence point of the two particle beams. The sample 74 is held on a displaceable sample stage 75 by means of a sample holder (not shown), and the sample is located in the sample chamber 62 of the dual-beam device, in which vacuum conditions usually exist during operation.

[0134] The sample stage 75 is advantageously configured as a five-axis sample stage. This means that the sample 74 can be moved in the x, y, and z directions (i.e., in three mutually perpendicular spatial directions), and can be rotated about an inclination axis and a rotation axis. Rotation about an inclination axis extending at right angles to the plane spanned by the optical axes 66, 78 (i.e., perpendicular to the plane of the drawing) allows the surface of the sample (which is intended to be irradiated by charged particles) to assume different adjustable angles relative to the optical axes 66, 78.

[0135] During operation, primary electrons are generated in the electron source 64, and the primary electrons are accelerated along the optical axis 66 of the electron beam column 63, focused by the lens systems 65, 67, and shaped by at least one aperture diaphragm 68. In addition, the electron beam column 63 includes a deflection system 69 through which the primary electron beam can be guided onto the surface of the sample 74. Furthermore, the FIB-SEM combination device 61 includes at least one detector 70 for detecting interaction products of the interaction between the particle beam and the sample 74.

[0136] In addition, the dual-beam device 61 includes an ion beam column 79 having an ion source 80, a deflection system 77, and a focusing lens element 76. The ions generated in the ion source 80 are accelerated and focused along the optical axis 78 of the ion beam column 79 such that the ions impinge on the sample 74 in a focused manner and can be used to ablate the material of the sample 74 and / or image the sample 74.

[0137] Advantageously, the particle beam device further has a gas injection system (GIS) 73. The gas injection system generally includes at least one reservoir for a process gas, which can be supplied to the sample 74 via a pipeline terminating near the processing site. The process gas can be implemented as a precursor gas. The precursor gas is initially activated by an ion beam or an electron beam and is thus converted into a reactive form capable of ablating the sample material or depositing material at the sample 74. For example, a precursor gas of xenon difluoride (XeF 2 ) can be supplied, which is converted into reactive xenon difluoride by activation, thereby etching the sample material. The processing of the sample 74 can be observed simultaneously or successively by means of the electron beam column 63 and the detector 70.

[0138] In addition, the particle beam device 62 includes a control device 72 and a storage device 71. Data records that describe the sample position and are used to position the sample according to the invention can be stored and processed by means of the storage device 71. As a result of the interaction between the storage device 71 and the control device 72, the sample stage can be displaced in such a way that the region of interest (ROI) of the sample is moved to and held at a predetermined position.

[0139] The control device 72 can execute a sequence of control commands included in a computer program. As a result of executing this sequence of control commands, the particle beam device 61 is prompted to perform the positioning method according to the invention.

[0140] The positioning method according to the invention is not limited to the exemplary microscope system shown. It is also conceivable to use the method according to the invention when observing and / or processing samples intended to be examined using other microscope systems (for example using an optical microscope or an X-ray microscope).

[0141] Particularly advantageously, the method according to the invention is carried out using a microscope system having an optical or particle-optical system with a defined optical axis and a movable sample stage for receiving a sample.

[0142] By means of the sample stage, a first region of the sample can be brought into different positions (i.e., locations and spatial orientations) relative to the optical axis of the microscope system. Similarly, a second sample region can be moved to different positions relative to the optical axis. In each case, the location and spatial orientation of the first sample region and the second sample region can be described by different data records. In addition, the microscope system includes a storage device for storing the data records and a control device for controlling the movement of the sample stage, which movement is carried out by means of the stored data records. In addition, the microscope system includes a user interface having a display device on which information can be displayed in the fields of a two-dimensional table.

[0143] Here, the fields in the first row or column of the two-dimensional table are assigned to the first sample region. In addition, the two-dimensional table has at least one second column or row extending parallel to the first column or row. The fields of the second column or row are assigned to the second region of the sample. The data records are assigned to the fields, which are stored in the data storage device and correspond to the different locations and / or spatial orientations of the sample regions relative to the optical axis. Thus, in each case, the position (i.e., location and spatial orientation) of the sample region is assigned to the field of the table.

[0144] Here, the data records assigned to the fields of the first row or column correspond to the locations and spatial orientations that the first sample region can assume relative to the optical axis. The data records assigned to the fields of the second row or column correspond to the positions that the second sample region can assume relative to the optical axis.

[0145] Particularly advantageously, the control device is implemented in such a way that the positions described by the stored data records can be accessed by an input on the user interface. For example, the sample stage can be moved by clicking or otherwise selecting a selected field in the two-dimensional table. For this purpose, the data record assigned to the selected field is used. The sample region assigned to the field is moved until it assumes the location and spatial orientation relative to the optical axis described in the associated data record.

[0146] In addition, it is conceivable to confirm and calculate the sample position of the second sample area starting from the sample position of the first sample area of interest by means of an analogical conclusion. For this purpose, the user interface should be implemented such that commands can be assigned to the stored data records. Here, the data records are each assigned to a field, which in turn is assigned to the first area or the second area of the sample. Here, the control device can calculate and assign the associated data record for the field assigned to the second area of the sample, wherein the calculated data record corresponds to the command assigned to the field. The command is based on the relational knowledge regarding the relationship between the first sample position and the second sample position, and the command provides information on how the sample stage must be moved to move the sample area from the first sample position to the second sample position.

[0147] When calculating the data record, the stored data record assigned to the second sample area is taken into account in another field assigned to the second area. In addition, the stored data record is considered when calculating the data record, the stored data record being assigned to the first area of the sample, the first area being assigned to the same field as the field to which the data record should be calculated and assigned is assigned the same command.

[0148] In addition, it is conceivable that the user interface of the microscope system is implemented to assign commands from a command list to the fields assigned to the first sample area and / or the fields assigned to the second sample area. For this purpose, the control device is implemented in such a way that the associated data record can be calculated and assigned to the selected field, the data record corresponding to the command assigned to the selected field. When calculating the data record, the stored data record is considered, the stored data record being assigned to another field assigned to the same area of the sample.

[0149] List of reference numerals

[0150] 1 Electron beam column

[0151] 2 Transfer rack

[0152] 3 First sample rack

[0153] 4 Sample stage

[0154] 5 Second sample rack

[0155] 6 Sample block

[0156] 7 Ion beam column

[0157] 8 Optical axis of the electron beam column

[0158] 9 Optical axis of the ion beam column

[0159] S1 Step 1

[0160] S2 Step 2

[0161] Step 3 of S3

[0162] S4: Step 4

[0163] S5: Step 5

[0164] S6: Step 6

[0165] S7: Step 7

[0166] S8: Step 8

[0167] S9: Step 9

[0168] 31 First column

[0169] 32 Second column

[0170] 33 First field

[0171] 34 Second field

[0172] 35 Third field

[0173] 36 Fourth field

[0174] 37 Second row

[0175] 38 First row

[0176] 39 Row

[0177] 40 First column

[0178] 41 Second column

[0179] S41 Step 1

[0180] S42 Step 2

[0181] S43 Step 3

[0182] S44 Step 4

[0183] 51 First column

[0184] 52 Second column

[0185] 61 Dual-beam device

[0186] 62 Sample chamber

[0187] 63 Electron beam column

[0188] 64 Electron source

[0189] 65 First condenser lens element system

[0190] 66 Optical axis of the electron beam column

[0191] 67 Second condenser lens element system

[0192] 68 Aperture stop

[0193] 69 Deflection system

[0194] 70 Detector

[0195] 71 Storage device

[0196] 72 Control device

[0197] 73 Gas injection system

[0198] 74 Sample block

[0199] 75 Sample stage

[0200] 76 Focusing lens element

[0201] 77 Deflection system

[0202] 78 Optical axis of the ion-optical column

[0203] 79 Ion-optical column

[0204] 80 Ion source

[0205] 100 Graphical user interface

[0206] 101 Setup button (generate data record)

[0207] 102 Go-to button (approach sample position)

[0208] 103 Save button (store data record)

[0209] 104 Delete button (delete data record)

[0210] 105 Edit button (edit data record)

Claims

1. A method for positioning a sample in a microscope system, wherein, an area of interest on the sample is observed and / or processed using the microscope system, and the microscope system comprises: - an optical system or a particle-optical system that defines an optical axis, - a movable sample stage for receiving the sample, by means of which the sample can be held in a first position and a second position relative to the optical axis of the microscope system; - a storage device for storing data records describing these positions; - a control device that controls the movement of the sample stage by means of the stored data records; and the method comprises the following steps: a) Holding the sample area in the first position; b) Storing a first data record that describes the first position and the spatial orientation of the sample area in the first position, wherein the first position is defined as an independent position; c) Storing a second data record that describes the second position and the spatial orientation of the sample area in the second position, wherein the second position is linked to the independent position; d) Invoking the second data record such that the movable sample stage moves so that the sample area is held in the second position, wherein, for a second area of interest of the sample, method steps a) to d) are repeated, successively approaching sample positions in a defined order, and the first data record defines the first position in three mutually perpendicular spatial directions, and the second data record defines the second position in the three mutually perpendicular spatial directions.

2. The method according to claim 1, wherein, the linking is implemented by calculating the second position using a computational operation.

3. The method according to claim 1, wherein, the linking is implemented by manually approaching the second position.

4. The method according to any one of claims 1 to 3, wherein, the data records can be presented in a two-dimensional table.

5. The method according to claim 4, wherein, the data records are saved in such a way that the relationships between the data records are represented by the layout in the two-dimensional table.

6. The method according to claim 4, wherein, the data records of the second area of interest of the sample are also presented in the two-dimensional table.

7. The method according to any one of claims 1 to 3, wherein, the data records are editable.

8. The method according to any one of claims 1 to 3, wherein, at least one rule is recorded that defines the management logic between two sample positions such that the sample can only be positioned in those sample positions permitted according to the rule.

9. The method according to any one of claims 1 to 3, wherein, the sample stage comprises at least two axes, and the movement of the sample stage is defined by the order, speed and degree of movement of the axes, and wherein at least one rule is recorded that specifies the order, speed and degree of movement of these axes for positioning the sample.

10. The method according to any one of claims 1 to 3, wherein, when correcting the sample position, the accuracy of positioning the region of interest of the sample is improved by storing the corrected position.

11. The method according to claim 4, wherein, the two-dimensional table is implemented as a graphical user interface.

12. The method according to any one of claims 1 to 3, wherein, a charged particle beam is generated in the microscope system.

13. The method according to any one of claims 1 to 3, wherein, the microscope system includes an electron beam column.

14. The method according to any one of claims 1 to 3, wherein, the microscope system includes an ion beam column.

15. A microscope system, comprising: - an optical system or a particle-optical system that defines an optical axis, - a movable sample stage for receiving a sample, by means of which the sample can be held in a first position and a second position relative to the optical axis of the microscope system, wherein the first position can be described by a first data record and the second position can be described by a second data record; - a storage device for storing the data records, wherein the data records can be stored in a two-dimensional table; - a control device that can control the movement of the sample stage by means of the stored data records; wherein the microscope system is configured to perform a method for positioning the sample, the method comprising the following steps: A) Holding a sample region in the first position; B) Storing a first data record that describes the first position and the spatial orientation of the sample region in the first position, wherein the first position is defined as an independent position; C) Storing a second data record that describes the second position and the spatial orientation of the sample region in the second position, wherein the second position is linked to the independent position; D) Invoking the second data record such that the movable sample stage moves so that the sample region is held in the second position, wherein method steps A) to D) are repeated for a second region of interest of the sample, successively approaching sample positions in a defined order, and the first data record defines a first position in three mutually perpendicular spatial directions, and the second data record defines a second position in the three mutually perpendicular spatial directions.

16. A microscope system, comprising: - an optical system or a particle-optical system that defines an optical axis, - a movable sample stage for receiving a sample, by means of which a first region of the sample can be brought to different locations and spatial orientations relative to the optical axis of the microscope system, and by means of which a second region of the sample can be brought to different locations and spatial orientations relative to the optical axis of the microscope system, wherein the different locations and spatial orientations of the first region and the second region of the sample can be described by different data records respectively; - A storage device for storing data records, the data records including: a first data record for a first position of the sample in three mutually perpendicular spatial directions, the first position of the sample being defined as an independent position; and other data records for positions of the sample linked to the independent position in the three mutually perpendicular spatial directions, the data records being storable in a two-dimensional table; - A control device for controlling the movement of the sample stage by means of the data records stored in the storage device; - A user interface having a display device on which information items can be displayed in fields of a two-dimensional table, wherein fields in a first row or column of the two-dimensional table are assigned to a first region of the sample, and fields in a second row or column parallel to the first row or column are assigned to a second region of the sample; And wherein the data records stored in the storage device are assigned to fields of the two-dimensional table, the data records corresponding to different locations and / or spatial orientations of the sample relative to the optical axis, wherein the data records assigned to the fields of the first row or column, correspond to different locations and / or spatial orientations of the first region of the sample relative to the optical axis; and, the data records assigned to the fields of the second row or column, correspond to different locations and / or spatial orientations of the second region of the sample relative to the optical axis; wherein each data record contains additional information such that the relationships between all data records are represented in the two-dimensional table; And wherein the control device is implemented to move the sample stage relative to the optical axis when the user interface is initiated at a selected field of the two-dimensional table, the movement proceeding until the first region or the second region of the sample assigned to the selected field assumes the location and / or spatial orientation relative to the optical axis described in the data record assigned to the selected field, and successively approaching the sample positions in a defined order.

17. The microscope system according to claim 16, wherein, the user interface is implemented to assign commands to the stored data records assigned to the fields of the two-dimensional table assigned to the first region of the sample; and the user interface is further implemented to assign commands to the stored data records assigned to the fields of the two-dimensional table assigned to the second region of the sample, wherein the control device is implemented to calculate and assign associated data records for the fields assigned to the second region of the sample, the associated data records corresponding to the commands assigned to the fields. Wherein, when calculating the data record, the stored data records of the second region assigned to the sample are considered in different fields, other fields are assigned to the second region of the sample, and wherein the stored data records of the first region assigned to the sample are considered when calculating the data record, and the stored data records are assigned to fields having the same command as the field to which the data record should be calculated and assigned.

18. The microscope system according to claim 17, wherein, the user interface is implemented to assign commands in a command list to fields of the two-dimensional table assigned to the first region of the sample and / or fields of the two-dimensional table assigned to the second region of the sample, and wherein the control device is implemented to calculate an associated data record and assign it to a selected field, the associated data record corresponding to the command assigned to the selected field, and wherein stored data records are considered when calculating the data record, the stored data records being assigned to another field assigned to the same region of the sample.

19. A computer program product comprising a sequence of control commands that cause a microscope system to perform the method for positioning a sample according to any one of claims 1 to 14.

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