Sample holder system and method of setting the tilt angle of a microscopic sample

Abstract

The invention relates to a sample holder system for holding a microscopy sample in a microscopy system, a method for setting a tilt angle of a microscopy sample in a microscopy system having an optical axis, and a computer program product, wherein the sample holder system comprises a first and a second rotating element, which are rotatably connected to each other. In each case, the side surfaces of the two rotating elements enclose an angle α, as a result of which the rotating elements have a wedge-shaped cross section. The second rotating element is configured to receive the sample, while the first rotating element can be rotatably connected to a holder receiving surface. The rotating elements can each be rotated about a rotation axis by an angle β. The inclination of a third side surface, which can receive the sample, can be set by combining all the involved angles α and β.

Description

Technical Field

[0001] This invention relates to a sample holder system for particle beam microscopy, that is, a microscopic system operated with a charged particle beam, such as a scanning electron microscope (SEM) or an ion beam microscope (focused beam, FIB). Imaging, analyzing, and / or manipulating microscopic samples using such particle beam microscopy often requires the sample to be oriented in a specific manner in three-dimensional space. Background Technology

[0002] The spatial orientation of a sample is understood to refer to the alignment of the sample with respect to the optical axis, where the spatial orientation of the sample is the result of rotation of the sample about one or more axes. Rotation of the sample about an axis extending parallel to the optical axis of the particle beam microscope is referred to here as sample rotation. Rotation of the sample about an axis perpendicular to the axis of rotation is referred to as sample tilt, or hereinafter also as sample inclination.

[0003] Various solutions are known to enable tilting of samples within a microscope system.

[0004] For example, a sample stage with a tilting axis (a five-axis stage) can be used in particle beam microscopy. The sample stage typically includes at least three translational axes (x, y, z) and two rotational axes (R, T). One of the rotational axes acts as the tilting axis T, which is arranged perpendicular to the other rotational axis R. The rotational axis R is typically aligned parallel to one of the optical axes of the microscope system. Typically, the sample is laid on a flat sample holder, which is then mounted on the sample stage.

[0005] When using a five-axis sample stage, the alignment of the tilt axis T relative to the other movement axes is fixed. To tilt the sample to a specific spatial orientation, the tilt of the sample about the tilt axis T is combined with the rotation of the sample stage about the rotation axis R or the rotational mounting of the sample on the sample holder.

[0006] However, not every particle beam microscope has a sample stage with a tilting axis. For cost reasons, simple particle beam microscopes typically do not have a tilting axis. Particle beam laser microscope systems also do not always have a sample stage with a tilting axis. In some particle beam laser microscopes, the laser subsystem does not have a sample stage with a tilting axis, and therefore the incident angle of the laser beam relative to the sample surface cannot be changed. However, because the tilt of the resulting laser notch is, in principle, deviates from the incident angle of the laser beam, the sample needs to be tilted in the opposite direction to produce a laser notch perpendicular to the sample surface.

[0007] In an alternative solution, the sample is laid on a sample holder with a fixed or settable tilt angle (referred to as a "pre-tilted sample holder"). The alignment of the tilt axis relative to the sample holder is fixed here. To change the alignment of the tilt axis relative to the sample, the sample must be mounted on the sample holder with the changed alignment.

[0008] For example, if the tilt angle range of the tilt axis T of the sample stage is not large enough, then a pre-tilted sample holder is required.

[0009] If the sample surface is not parallel to the xy-plane of the sample stage, a pre-tilted sample holder is required. In this case, it may be necessary to tilt the sample, but not rotate it. This requirement may exist, for example, in the case of samples mounted in a non-planar manner and having a structure with a preferred orientation (e.g., a semiconductor structure).

[0010] Depending on the availability of features for tilting and rotating the sample stage, a combination with a correspondingly designed pre-tilted sample holder is feasible.

[0011] However, a drawback of sample holders with tilted axes is that these sample holders are very small, making it difficult to set the tilt angle accurately and repeatably. This is true even if angular scales are present.

[0012] The disadvantage of a sample holder with a fixed tilt angle is that the tilt angle of the sample surface corresponds to the angle specified by the sample holder only when the sample is mounted such that the sample surface is correctly parallel to the placement surface of the sample holder.

[0013] Furthermore, the tilt angle cannot be changed. To set another tilt angle, a sample stage with a tilt axis must be used.

[0014] In addition, a disadvantage is that the laid samples usually cannot be rotated.

[0015] In other words, the alignment of the sample in the inclined plane cannot be easily changed. Therefore, the placement surface would need to have a rotatable receiving device. If this is not the case, then the sample needs to be removed and laid out with proper rotational alignment.

[0016] Another drawback arises when the sample holder is rotated by rotating the sample stage about the axis of rotation R or by rotating the sample holder on the sample stage. In this case, the effective tilt angles relative to the x and y axes of the sample stage are not significant. These effective tilt angles need to be calculated or determined experimentally.

[0017] Therefore, it is desirable to propose an apparatus and method for achieving precise and stable alignment of the sample surface at all solid angles.

[0018] What is particularly advantageous here is that the tilt of the sample surface can be continuously adjusted.

[0019] Depending on the specific application, the required maximum tilt angle can be different. Therefore, a flexible system that can provide different maximum tilt angles for different applications would be desirable.

[0020] Various five-axis and six-axis stages are known in the prior art for use in microscope systems.

[0021] EP 2 001 038 A2 (Zeile and Schertel) describes a pre-tilted sample holder.

[0022] DE 102018212511 B4 (Nicoletti and Biberger) discloses a sample holder system that provides additional degrees of freedom of movement. Summary of the Invention

[0023] The purpose of this invention is to provide a sample holder system that allows for the continuous orientation of the sample to be examined relative to the optical axis of a microscope system. This sample holder system achieves precise and stable alignment of the sample surface at all solid angles, which facilitates the examination and / or processing of the sample within the microscope system.

[0024] This objective is achieved by means of the apparatus described below. Favorable configurations are also specified below.

[0025] The present invention provides a sample holder system for holding a microscopic sample in a microscope system having at least one optical axis, wherein the sample holder system comprises:

[0026] -First rotating element and second rotating element,

[0027] -The first rotating element has a first side surface and a second side surface, which are opposite to each other and form an angle α1, such that a wedge-shaped cross-section is obtained for the first rotating element; and

[0028] - The second rotating element has a third side surface and a fourth side surface, which are arranged opposite to each other and form an angle α2, in such a way that a wedge-shaped cross section of the second rotating element is obtained;

[0029] -The second rotating element is configured to receive the sample or the third rotating element on the third side surface;

[0030] - And the second rotating element is rotatably connected to the first rotating element, wherein the second rotating element has a rotation axis R2 arranged perpendicular to the fourth side surface, and the second rotating element can rotate about the rotation axis R2 relative to the first rotating element by a rotation angle β2;

[0031] - and the first rotating element is configured to be rotatably received on the retainer receiving surface, wherein the first rotating element has a rotation axis R1 arranged perpendicular to the second side surface, wherein the first rotating element can rotate about the rotation axis R1 relative to the retainer receiving surface by a rotation angle β1.

[0032] -The inclination of the third side surface of the second rotating element relative to the receiving surface of the holder can be set by a combination of these angles α1, α2, β1 and β2.

[0033] Preferably, the fourth side surface and the first side surface are arranged opposite to each other and aligned parallel to each other, such that the rotation axis R2 of the second rotating element is perpendicular to the first side surface of the first rotating element; and furthermore, the first rotating element is configured such that the second side surface can be received on the holder receiving surface, such that the second side surface and the holder receiving surface are arranged opposite to each other, wherein the second side surface and the holder receiving surface are aligned parallel to each other, such that the rotation axis R1 of the first rotating element is aligned perpendicular to the holder receiving surface.

[0034] Preferably, the sample holder system includes a third rotating element having a sample receiving surface and side surfaces arranged opposite to each other; and the third rotating element is configured to receive a sample on the sample receiving surface of the third rotating element; and the third rotating element is rotatably connected to the second rotating element, wherein the third rotating element has a rotation axis R3 arranged perpendicular to the side surface of the third rotating element, and the third rotating element is rotatable about the rotation axis R3 relative to the second rotating element at an angle β3.

[0035] Preferably, the side surface of the third rotating element and the third side surface of the second rotating element are arranged opposite each other and aligned parallel to each other, such that the rotation axis R3 is aligned perpendicular to the third side surface of the second rotating element.

[0036] Preferably, the sample holder system includes a base plate that can be mounted on a sample stage, and the base plate has a side surface designed as a holder receiving surface.

[0037] Preferably, these angles α1 and α2 are fixed values, while these angles β1 and β2 are optional.

[0038] Preferably, these angles α1 and α2 are values ​​between 0° and 45° and include 0° and 45°.

[0039] Preferably, these angles α1 and α2 use different values.

[0040] Preferably, these rotating elements have a scale for setting the rotation angle β.

[0041] Preferably, these scales are designed such that they correspond to the mathematical relationship between the desired tilt angle and these wedge angles α and these rotation angles β.

[0042] Preferably, the sample holder system is configured such that it can be received in a microscope system, which is implemented in the form of a particle beam microscope.

[0043] Preferably, these rotating elements have a circular or elliptical base.

[0044] The spatial orientation of a sample can be altered by tilting. Tilt is understood to mean that the sample rotates in space around an axis (the tilt axis, which is known), which is typically aligned perpendicular to the optical axis of the microscope system. For example, the tilt axis can be aligned perpendicular to the optical axis of an electron or ion beam column.

[0045] Spatial orientation is understood to mean the alignment of the sample with respect to the optical axes of the microscope system in which the sample is observed and / or processed.

[0046] Another object of the present invention is to provide a method for continuously adjusting the tilt angle of a sample in a microscope system, wherein the sample can be tilted in any desired spatial direction.

[0047] This objective is achieved as described below.

[0048] This invention provides a method for setting the tilt angle of a microscopic sample in a microscope system with an optical axis, wherein the sample is held by the sample holder system described above, and the method includes the following steps:

[0049] a) The sample is held in place by the sample holder system;

[0050] b) The first rotation angle β1 is changed by rotating the first rotating element about the rotation axis R1;

[0051] c) By rotating the second rotating element about the rotation axis R2, the second rotation angle β2 is changed, and as a result, these angles α1, α2, β1 and β2 are combined to change the inclination of the sample relative to the receiving surface of the holder.

[0052] d) Repeat steps b) and c) until the sample has the desired tilt relative to the retainer receiving surface.

[0053] Preferably, the method includes the following additional steps:

[0054] e) The third rotation angle β3 is changed by rotating the third rotating element about the rotation axis R3 in such a way that the sample presents the desired orientation in a plane parallel to the third side surface.

[0055] In addition, the present invention relates to a computer program product that enables a microscope system to perform the method according to the present invention.

[0056] The present invention is based on the discovery that the tilt angle of the sample held in a sample holder system can be set by the combined action of at least two wedge-shaped rotating elements arranged one after another in an open kinematic chain.

[0057] For this purpose, the rotating elements are rotatably connected to each other. By selectively rotating individual rotating elements, any desired tilt angle θ (tilt angle) of the sample receiving surface (and thus the sample held) can be continuously adjusted in both size and orientation. The sample is advantageously tilted relative to one of the optical axes of the microscope system, in which a sample holder system is used.

[0058] To tilt the sample according to the invention, at least two rotating elements of the sample holder system have a wedge-shaped cross-sectional profile. This is achieved by each rotating element having two side surfaces aligned opposite to each other but not parallel to each other. Rather, the side surfaces form a non-zero angle α. Thus, angle α forms the wedge angle of the wedge-shaped rotating element in each case. For example, angle α can be an acute angle. The wedge angle α1 of the first rotating element and the wedge angle α2 of the second rotating element advantageously have values ​​greater than 0° and at most 45°, for example, 10°. In a particularly advantageous configuration, angle α = 45°.

[0059] Rotating elements can each have a circular, elliptical, or square shape, or a base with a different shape.

[0060] The first rotating element is designed so that it can be received on the retainer receiving surface of the base element. The base element can be implemented in the form of a base plate, which is designed to be compatible with the receiving device of the sample stage. This means that the base plate of the sample holder system can be received on the sample stage of the microscope system.

[0061] Alternatively, it is conceivable to use the sample holder system in microscope systems without a sample stage. In this particular case, the sample holder system according to the invention can function as a sample stage. For this purpose, the first rotating element is configured in a particular embodiment such that it can be directly received in a receiving device of any design within the microscope system.

[0062] Because the tilting and rotation of the sample can be set independently of each other through the coordinated movement of the at least two rotating elements, the function of the rotatable rotating element according to the invention can replace the tilting and rotation axes of a conventional sample stage.

[0063] Furthermore, the eccentric rotating element can generate lateral displacement of the sample by moving in coordination with the movement of other rotating elements, thus replacing the linear shaft of the conventional sample stage used for lateral displacement of the sample within certain limits. Using a rotating shaft with a spindle-shaped thread instead of a pin-shaped rotating shaft can replace the height adjustment of the conventional sample stage within certain limits.

[0064] In an advantageous embodiment, the second rotating element of the sample holder system is designed to receive the sample to be examined. For this purpose, a sample receiving portion may be provided on the upper surface of the second rotating element (hereinafter also referred to as the sample receiving surface).

[0065] Here, the term "upper" in each case refers to the side surface facing the sample. In the operational state, that is, when the sample holder system is used in a microscope system, the "upper" side surface is therefore arranged such that it faces the incident particle beam. In contrast, the "lower" side surface refers to the side surface of the rotating element facing the holder receiving surface (i.e., the base element).

[0066] Each rotating element of the sample holder system has an axis of rotation, and the corresponding rotating elements are arranged around this axis of rotation to make them rotatable. This means that the first rotating element has a first axis of rotation, and the first rotating element can rotate about the first axis of rotation at an angle β1. The second rotating element has a second axis of rotation, and the second rotating element can rotate about the second axis of rotation at an angle β2.

[0067] Here, the second rotating element is rotatably connected to the first rotating element, which in turn is rotatably connected to the base element. The rotating elements are stacked one on top of the other and can be received together on the base element. In this way, the sample holder system according to the invention provides at least two rotational degrees of freedom for moving the received sample.

[0068] Angles β1 and β2 can be freely chosen or chosen within certain limits. In particular embodiments, it is also conceivable that one of the angles β is fixed.

[0069] In an alternative embodiment, the second rotating element rotatably receives the third rotating element instead of the sample, wherein the third rotating element thus functions to receive and hold the sample. Therefore, in this embodiment, the upper surface of the third rotating element acts as the sample receiving surface (hereinafter also referred to as the sample receiving surface of the third rotating element).

[0070] The third rotating element has a third axis of rotation and is arranged to rotate about the third axis of rotation by a rotation angle β3.

[0071] Advantageously, the third rotating element is designed to achieve additional rotation of the sample without changing its tilt angle. For this purpose, it is advantageous that the third rotating element is cylindrical, and that the third axis of rotation extends parallel to the cylindrical axis and perpendicular to the upper surface of the second rotating element. Particularly advantageously, the upper and lower surfaces of the third rotating element are aligned parallel to each other. In other words, the third rotating element is not wedge-shaped. This ensures that the tilt angle of the sample is maintained even as the third rotating element rotates.

[0072] The advantage of rotating the sample using a third rotating element is that it also allows for optimal alignment of the sample for observation and / or processing purposes, even when the sample is tilted.

[0073] The third rotating element can be circular, elliptical, square, or another basic shape.

[0074] In addition, it is conceivable that the sample holder system also includes additional rotating elements, which are designed as described and work together to hold the sample tiltably and rotatably on the sample holder system.

[0075] Due to the wedge-shaped profile of the rotating element, and because the two rotational degrees of freedom can be coordinated with each other, a sample holder system can be used to continuously adjust the tilt and orientation of the held sample. When the sample holder system is mounted on a multi-axis sample stage, the latter typically provides an additional degree of motion freedom.

[0076] In principle, the wedge angle α1 of the first rotating element and the wedge angle α2 of the second rotating element can be the same. However, the sizes of angles α1 and α2 can also be different, which means that the rotating elements have wedge shapes with different steepness. Furthermore, it is conceivable to use a set of different rotating elements, each with a different wedge angle αx. Particularly advantageous is the ability to flexibly set different tilt angles depending on the relevant application.

[0077] The present invention also relates to a method for setting the tilt angle of a sample held in a microscope system by means of the described sample holder system.

[0078] The rotation angles β1 and β2 are selectively changed by rotating the first and second rotating elements. The combination of rotation angles β1 and β2 and wedge angles α1 and α2 is such that the inclination of the sample relative to the holder receiving surface of the base element and relative to the one or more optical axes is settable.

[0079] If the sample holder system used has an additional third rotating element without a wedge profile, then not only can the tilt of the sample be set as needed, but also the alignment of the sample relative to these optical axes can be set. Attached Figure Description

[0080] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. For the purpose of illustrating the components, reference will be made to the entire preceding and following descriptions, respectively.

[0081] Figure 1 An exploded view illustrates an advantageous embodiment of the sample holder system according to the invention, wherein the sample holder system comprises three rotating elements.

[0082] Figure 2 shows two different operating states ( Figure 2a , Figure 2c )of Figure 1 The sample holder system and top view ( Figure 2b ).

[0083] Figure 3 An alternative embodiment consisting of only two rotating elements is shown.

[0084] Figure 4 The x-direction of the coordinate system of the reference base element shows the dependence of the settable tilt angle of the received sample on the rotation angles β1 and β2.

[0085] Figure 5 The y-direction of the coordinate system of the reference base element shows the dependence of the tilt angle of the received sample on the rotation angles β1 and β2.

[0086] Figure 6 A dual-beam device is shown by way of example, which is configured to receive a sample holder system according to the invention.

[0087] Figure 7 A flowchart of a method for tilting a sample by means of a sample holder system according to the present invention is shown. Detailed Implementation

[0088] Figure 1 An advantageous embodiment of the sample holder system 20 is shown, wherein the sample holder system 20 has three rotating elements 1, 8, 15 that work together.

[0089] The sample holder system 20 includes a first rotating element 1 having a first side surface (upper side surface) 2 and a second side surface (lower side surface) 3. The first side surface 2 and the second side surface 3 are arranged opposite to each other and form an angle α1. In other words, the first rotating element 1 has a wedge shape, wherein the two side surfaces 2, 3 converge at an acute angle α1. Importantly, the first side surface 2 and the second side surface 3 are not aligned parallel to each other, but rather extend toward each other and form an angle α1.

[0090] like Figure 1 As shown, the cross-section of the rotating element 1 implemented in a wedge shape can have an irregular right-angled triangular shape. However, the invention is not limited to this shape. It is also conceivable that the wedge shape in the cross-sectional profile does not have right angles, but is formed by any arbitrary acute-angled triangle. Here, the cross-sectional profile can be an irregular, isosceles, or equilateral triangular shape. The side of the rotating element opposite to angle α can have any desired design, such as a straight line (in the cross-sectional profile) or a portion of a circle (in the cross-sectional profile).

[0091] The first rotating element 1 has a rotation axis R1, about which it is rotatably arranged. Particularly advantageously, the first rotating element 1 can be rotatably connected to the base element 4, wherein rotation is achieved via the rotation axis R1.

[0092] The base element 4 can exist in the form of a base plate 4 or a sample stage of a microscope system.

[0093] The base plate 4 is understood to refer to a structural component that can be mounted on the sample stage of a microscope system, and can also receive the rotating element 1. It has been found particularly advantageous that the base plate 4 has, for example, a flat cuboid shape. However, the base plate 4 can also be cylindrical or have a polygonal shape or another shape. In any case, the shape of the base plate should be chosen so that the movement of the rotating element is not obstructed by the base plate.

[0094] In an alternative embodiment, the sample stage of the microscope system serves as the base element 4. In this case, the first rotating element 1 is directly rotatably mounted on the sample stage.

[0095] The common feature of the embodiments described for the base element 4 is that the base element 4 in each case has a sample holder receiving surface 5 (hereinafter also referred to as the holder receiving surface), which can be arranged perpendicular to the optical axis of the microscope system during operation of the sample holder system 20 in the microscope system.

[0096] In a preferred embodiment of the sample holder system, the first rotating element 1 is configured such that its axis of rotation R1 is aligned perpendicular to the holder receiving surface 5. For this purpose, the first rotating element 1 is configured such that a second side surface 3 can be received on the holder receiving surface 5. In this case, the second side surface 3 and the holder receiving surface 5 can be arranged such that they are opposite each other and parallel to each other. In this way, the axis of rotation R1 is aligned perpendicular to both the second side surface 3 (of the first rotating element 1) and the holder receiving surface 5 (of the base element 4).

[0097] The precise alignment (spatial orientation) of the base element 4 and therefore the retainer receiving surface 5 can be described using a coordinate system. The coordinate system of the base element has spatial axes z0, x0, and y0, which are each arranged orthogonally to each other.

[0098] It is particularly advantageous here that the retainer receiving surface 5 of the base element 4 is arranged in the plane spanned by the two spatial axes (e.g., x0 and y0) of the coordinate system.

[0099] The changes in the spatial orientation of sample 16 are in each case referenced to the coordinate system of base element 4. These changes in spatial orientation are caused by the sample holder system according to the invention and will be described below.

[0100] It has been found advantageous that the rotation axis R1 of the first rotating element 1 is aligned with one of the axes parallel to the base element 4. It is particularly advantageous here that the rotation axis R1 is parallel to the axis z0.

[0101] To rotatably connect the first rotating element 1 to the base element 4, the base element 4 may have, for example, a hole 6 into which a pin-type connector 7 connected to the first rotating element 1 can be precisely inserted. The longitudinal axis of the pin 7 corresponds to the rotation axis R1 about which the first rotating element 1 can rotate relative to the base element 4. Here, the first rotating element 1 can rotate relative to the retainer receiving surface 5 by a rotation angle β1. The rotation axis R1 is aligned perpendicular to the y0 axis of the base element 4.

[0102] Furthermore, the sample holder system 20 has a second rotating element 8, which also has two opposing side surfaces, specifically a third side surface 9 (upper side surface) and a fourth side surface 10 (lower side surface), which together form an acute angle α2. That is, the second rotating element 8 also has a wedge shape, which can be designed as described above for the first rotating element 1.

[0103] The second rotating element 8 has a rotation axis R2, about which it is rotatably arranged, and is rotatably connected to the first rotating element 1. The rotation axis R2 is aligned perpendicular to the fourth side surface 10 of the second rotating element 8.

[0104] Of particular advantage, the fourth side surface 10 and the first side surface 2 of the first rotating element are arranged such that they are opposite each other and aligned parallel to each other. The rotation axis R2 of the second rotating element 8 is aligned not only perpendicular to the fourth side surface 10 but also perpendicular to the first side surface 2.

[0105] In addition, the sample holder system 20 includes a third rotating element 15 having a sample receiving surface 17 for receiving a sample and an opposite side surface 18.

[0106] The third rotating element 15 is configured to receive the sample 16 to be inspected. For this purpose, the sample 16 is laid onto the sample receiving surface 17 (upper surface) of the third rotating element 15, for example by means of a correspondingly designed sample receiving portion (not shown). Therefore, clamping devices, such as fixing screws, may be present. Alternatively, it is conceivable that the sample 16 is glued to the sample receiving portion or directly glued to the sample receiving surface 17 of the third rotating element to secure it.

[0107] The third rotating element 15 has a rotation axis R3, about which it can rotate relative to the second rotating element 8 at an angle β3. For this purpose, the third rotating element 15 is rotatably connected to the second rotating element 8, wherein the third rotation axis R3 is aligned perpendicular to the side surface 18 of the third rotating element 15.

[0108] Advantageously, the side surface 18 of the third rotating element and the third side surface 9 of the second rotating element are arranged opposite each other and aligned parallel to each other, so that the rotation axis R3 is perpendicular to the side surface 18 of the third rotating element and perpendicular to the third side surface 9 of the second rotating element 8.

[0109] It has proven particularly advantageous that the third rotating element 15 has a pin-type connector 19, which can be inserted into a hole 13 of the same diameter at the center of the upper surface 9 of the second rotating element 8. The connecting pin 19 serves as a rotation axis / shaft R3, through which the third rotating element 15 can rotate coaxially with the central axis of the upper surface 9 of the second rotating element 8 at an angle β3 relative to the second rotating element 8.

[0110] The base of the rotating element can be, for example, circular (e.g.) Figures 1 to 3(As shown) or elliptical. However, the design of rotating elements is not limited to the shapes described above. Rather, it is conceivable that rotating elements can have any other desired shape.

[0111] Instead of connecting the described rotating element to the hole and pin connection, a rotatable bearing can be used. For this purpose, ball bearings or other suitable mechanical connections can be used.

[0112] The rotating elements 1, 8, and 15 are described as acting in a manner that forms an open kinematic chain. For this purpose, the rotating elements 1, 8, and 15 are arranged in a specific order, i.e., sequentially. The sample to be examined is received here on the last rotating element of the chain.

[0113] An open kinematic chain arrangement means that, in each case, the rotating element not only performs the rotational movement it achieves, but also passively performs the movement of other moving elements arranged upstream of the rotating element in the chain. In other words, the rotational axes R1, R2...Rx of the sample holder system are stacked one on top of the other (also known as axis stacking).

[0114] When the sample holder system 20 is received on the sample stage during operation, the open kinematic chain also includes translational (x, y, and z axes) and rotational movement elements (R, T axes) that make the sample stage available.

[0115] In the description of rotating elements 1, 8, and 15, the terms "upper" and "lower" side surfaces refer to the arrangement of the rotating elements in the axial stack. Therefore, "lower" indicates the side of the corresponding rotating element facing the base element. In contrast, "upper" indicates the side of the rotating element facing the sample receiving section (i.e., the sample). Thus, during operation of the microscope system, the upper surface is always the surface facing the incident particle beam, while the lower surface faces away from the incident particle beam.

[0116] Figure 2 illustrates the operation, specifically in two different exemplary operating states. Figure 1 The sample holder system 20.

[0117] Figure 2a The case is shown where α1 = -α2, β1 = 0°, and β2 = 180°. In this case, the tilt angle θ of the sample receiving surface 17 (of the third rotating element) holding the sample is 0° in all directions. Therefore, the sample 16 will not tilt in any direction, and thus, the particle beam can be incident substantially perpendicularly on the sample surface during microscopic observation or inspection.

[0118] To illustrate spatial direction, Figure 2b This diagram shows a top-down view. In this illustration, the z-axis is perpendicular to the plane in which the drawing is performed.

[0119] Figure 2c Showing with Figure 2a Conversely, in the case of the rotating elements, the wedge angles are added together.

[0120] Here: α1 = -α2, and β1 = 0° and β2 = 0°. In the y-direction of the base element, this gives the maximum tilt angle θ of |α1| + |α2|.

[0121] In other words, the maximum tilt angle in the y-direction corresponds to the sum of the absolute values ​​of the wedge angles α1...αx. In contrast, the tilt angle of sample 16 in the x-direction of the base element is 0°.

[0122] However, the invention is not limited to the embodiment with three rotating elements described above. In another advantageous embodiment, such as... Figure 3 As shown, the third rotating element is omitted. In this case, the second rotating element 8 is configured to receive the sample. For this purpose, the second rotating element 8 may include a clamping device (e.g., a fixing screw) or a sample receiving part of another design type on its upper surface 9, in which the sample can be received. Alternatively, the sample can be glued on.

[0123] However, it is also conceivable that the sample holder system has more than three rotating elements. In this case, the sample holder system not only includes Figure 1 The three rotating elements shown, and further include similarly formed rotating elements arranged rotatably relative to each other.

[0124] As shown in Figure 2 and Figure 3 As shown, the tilting and rotation of the sample 16 held by the sample holder system 20, 21 according to the present invention is the result of the combination of all wedge angles αx and all rotation angles βx of the rotating element in the open kinematic chain.

[0125] In its simplest form, the sample holder system 21 consists of only two rotating elements 1 and 8.

[0126] Due to the combination of angles α1, α2, β1 and β2, the inclination of the upper surface 9 of the second rotating element 8 relative to the base element 4 (more precisely, relative to the retainer receiving surface 5 of the base element 4) can be freely set in terms of direction and degree.

[0127] As shown in Figure 2, the same applies if a third rotating element 15 is present. Because Figure 1 The third rotating element 15 in the embodiment shown in Figure 2 does not have a wedge shape (the upper surface 17 and the lower surface 18 are parallel to each other), so the combination of angles also determines the inclination of the upper surface (sample receiving surface) 17 of the third rotating element that carries the sample 16.

[0128] The tilt angles of the base element in the x and y directions depend on the wedge angles α1 and α2. Therefore, the mathematical relationship between these angles can be derived through analysis.

[0129] For example, the tilt angle of the upper surface (third surface) 9 of the second rotating element 8 in the x-direction of the base element is:

[0130] -acos((sin(β1)*cos(α1)*cos(β2)+sin(β2)*cos(β1))*sin(α2)+sin(α1)*sin(β1)*cos(α2))+π / 2.

[0131] The tilt angle of the upper surface (third surface) of the second rotating element in the y-direction of the base element is:

[0132] -acos((sin(β1)*sin(β2)-cos(α1)*cos(β1)*cos(β2))*sin(α2)-sin(α1)*cos(α2)*cos(β1))+π / 2.

[0133] If β1 and β2 change, the mounted sample also rotates. However, by rotating the third rotating element about the axis of rotation R3 at an angle β3, this rotation of the sample can be returned to its original spatial orientation. This means that the optional third rotating element provides additional degrees of freedom for moving the sample. It is particularly advantageous here that the set tilt angle does not change, because angles β1 and β2 are unaffected by rotation about R3.

[0134] The angle β3 to be chosen also depends on angles α1, α2, β1, and β2, and can be derived in a similar manner to the shape described above.

[0135] A particularly advantageous feature is that the rotation of the rotating element is achieved by a motor. For this purpose, a suitable motor can be installed in the base plate or sample stage. Alternatively, the drive motor can also be arranged externally to the sample holder system. Therefore, it is conceivable to induce the setting of the sample tilt in situ within the sample chamber of the microscope system by remotely controlling the motor from the outside, without requiring manual movement of the rotating element. The microscope system's software controller can be used for this purpose.

[0136] In a particular embodiment, it is also conceivable that the rotation of the rotating element is achieved passively, particularly by moving the sample stage using a suitable carrier device.

[0137] In the sample holder system according to the invention, it is also conceivable that the rotating elements used have different wedge angles α. This means that the wedge shape of the rotating elements is exhibited to varying degrees. In this way, rotating elements with different angles α can be combined. Therefore, the maximum tilt angle of the sample receiving surface achievable by the sample holder system can vary depending on the application and type of the sample.

[0138] If the sample is correctly mounted at the center of the second rotating element, the height of the sample surface above the surface of the base element is independent of the tilt angle. Therefore, the sample surface is concentric at this point, meaning that changes in the tilt angle will not cause a shift in the sample position.

[0139] It is conceivable that concentricity can be achieved for all tilt and rotation angles, regardless of the sample's position on the second or third rotating element, by using additional mechanical extensions. Such mechanical extensions could, for example, be supports for the rotating element on a threaded spindle with a suitable pitch, rather than simple pin-type connectors. Another possibility is a tilting support for the first rotating element on a base element, or a wedge-shaped embodiment of the third rotating element, or a combination of these possibilities.

[0140] like Figure 1 As shown in Figure 2, it has proven particularly advantageous that each of the rotating elements 1, 8, and 15 has a scale 11. The scale 11 is used to set angles β1 and β2 in a manner consistent with each other, such that the received sample 16 adopts a desired tilt and rotation position relative to the coordinate system of the holder receiving surface 5 (i.e., relative to the base element). The scales 11 are designed such that they correspond to the mathematical relationships between the desired tilt angles and wedge angles α1 to αx and rotation angles β1 to βx.

[0141] Due to the corresponding embodiment of the scale on the rotating element, the tilt angle of the upper surface of the second rotating element in the x and y directions of the base element can be set in a targeted and clear manner. Similarly, the rotation angle of the optional third rotating element can be set in a defined manner by means of the scale located on the third rotating element.

[0142] The tilt angle θ of the sample receiving surface (and therefore the sample) is set to decrease gradually, with this gradual decrease being greater as the wedge angles α1 and α2 become smaller. Therefore, the sample holder system according to the invention can be set with significantly higher precision than previously known adjustable tilt holders.

[0143] This is because in this sample holder system, the tilt angle is obtained by rotating the wedge-shaped rotating element in such a way that not only the tilt angle itself but also its error depends on the angle scale via the aforementioned mathematical relationship. Since the change in the rotation angle required to obtain a specific tilt angle is greater than the change in the tilt angle caused by the rotation angle itself, the setting error is also reduced to the same extent.

[0144] Since the desired tilt angle and the possible reverse rotation of the sample with β3 depend on α1 and α2, and also on β1 and β2, a mathematical formula for the design of the scale can be found.

[0145] For example, the total tilt can be set using the first scale, while the second scale sets the relative components of the tilt in the x and y directions.

[0146] If an inexperienced user cannot find a sufficiently easy-to-manage scale division, then software can be used to calculate the rotation angle to be set.

[0147] A particular advantage is that the sample holder system has no backlash when all rotating elements are fixed. In the electrically powered version of the sample holder system, backlash can be eliminated, for example, by frictional adhesion of the rotating elements or by suppression of the rotation motor.

[0148] Figure 4 and Figure 5 The dependence of the sample tilt angle in the spatial directions x and y is shown by referring to the upper reference coordinate system.

[0149] Figure 4 and Figure 5 This relates to the case where both wedge angles are α = 45° (that is, when α1 = 45° and α2 = -45°).

[0150] These figures show the dependence of the tilt angle of the upper surface of the second rotating element on the selected rotation angles β1 and β2, respectively.

[0151] exist Figure 4 In the diagram, the tilt angle is specified with reference to the x-direction of the base element's coordinate system. All angles in the diagram are shown in radians (rad).

[0152] exist Figure 5 In the reference frame, the tilt angle specification is determined by the y-direction of the coordinate system of the base element, and is consistent with... Figure 4 The same applies to the same situation.

[0153] The sample holder system according to the invention can be particularly advantageously used when processing samples in a SEM FIB assembly equipped with a laser device. When processing samples with a pulsed laser, the intention is usually to produce a cross-section oriented completely perpendicular to the sample surface. However, in principle, the result is always a cross-section tilted up to 20° relative to the vertical. The exact angle of deviation depends on the sample material and the laser parameters used. Because the laser beam cannot typically be set to different incident angles, a perpendicular cross-section can only be achieved by tilting the sample in the opposite direction. The present invention now represents a compact, precisely configurable solution that, if correspondingly designed, has a low profile (for such applications, for example, α1 = -α2 = 10° is sufficient).

[0154] Another important application of the laser option is the cutting of columnar objects from an entire sample, where the columnar objects range in size from tens to hundreds of micrometers. In this case, the intention is to cut columnar objects that are as cylindrical as possible, which is only possible by tilting the sample in the opposite direction. The tilting axis must rotate against the direction of the laser beam guided on a circular track. This can be implemented using an electrically driven version of the sample holder system according to the invention.

[0155] Another advantageous application of the sample holder system is the analysis of samples using a ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) detector. Here, the detector may be located on a different axis from the excitation FIB beam, for example, laterally and / or at a different height. In samples with varying surface topography, this leads to inhomogeneous detection. This situation can be avoided because the present invention provides additional degrees of freedom of movement, allowing the sample to be aligned differently relative to the detector.

[0156] Furthermore, it is conceivable to use the described sample holder system as an alternative to the swing stage application. The swing stage method is used to avoid the so-called "curtain effect" when generating sample cross-sections with a focused ion beam during material ablation by continuously tilting the sample stage concentrically back and forth. Using the sample holder system according to the invention, tilting can replace the back-and-forth swinging of the sample stage.

[0157] Figure 6 An example of the use of the FIB SEM assembly 60 illustrates a microscope system in which a sample holder system according to the invention can be used, and in which the method according to the invention can be performed.

[0158] In order to make the sample 75 available for microscopic examination or processing, the sample 75 is held by a sample holder system 74 according to the invention. The sample holder system 74 is mounted on a device, such as a sample stage 73, in the sample chamber 69 of the microscope system 60.

[0159] The sample stage 73 is arranged in the sample chamber 69 of the FIB-SEM assembly 60, where vacuum conditions dominate during operation.

[0160] Of particular advantage is that the sample stage 73 is designed as a multi-axis sample stage, thus providing multiple translational and rotational degrees of freedom. This is the case, for example, if the sample stage 73 were implemented as a five-axis stage including translational axes x, y, and z and rotational axes R and T (tilt axes). In this case, the aforementioned translational axes are aligned perpendicularly to each other in each case.

[0161] The sample 75 to be inspected can therefore be moved in three spatial directions, x, y and z, via a multi-axis stage to change the orientation of the sample 75.

[0162] This pose is understood to refer to the positioning of sample 75 in three-dimensional space. Given the x, y, and z coordinates, the correct pose can be described.

[0163] Furthermore, the spatial orientation, i.e. the alignment of the sample 75 with respect to the optical axes of the microscope system, can be changed by rotating and / or tilting the sample 75 with respect to the rotation axes R and T.

[0164] In this case, it is particularly advantageous that the sample stage is designed as a concentric sample stage 73. This means that the sample 75, arranged on the sample stage 73 and positioned at the concentric point, can be tilted without lateral movement. Alternatively, the sample stage can be designed as a so-called hyperconcentric six-axis stage with an additional M-axis.

[0165] The microscope system 60 includes two particle beam columns, specifically an electron beam column 61 for generating an electron beam and an ion beam column 81 for generating an ion beam. Both particle beams are directed at the sample 75 to be processed, which is advantageously located at the point of overlap of the two particle beams.

[0166] For microscope system 60 excluding the sample stage (different from the case where the sample stage is not included) Figure 6 As shown in the figure, the sample holder system 74 can also be installed on different devices in the sample chamber 69.

[0167] During operation of the FIB-SEM assembly 60, primary electrons are generated in the electron source 62. These primary electrons are focused, parallelized, or scattered along the optical axis 64 of the electron beam column by a condenser lens system or multiple condenser lens systems 63, 65 and are trimmed by at least one aperture stop 66. Furthermore, the electron beam column 61 includes a deflection system 67 that allows the primary electron beam to be guided onto the sample 75 in a grating manner, and also includes an objective lens system 68 by means of which the primary electron beam can be focused onto the sample 75.

[0168] Furthermore, the FIB-SEM assembly 60 includes an ion beam column 81 with an ion source 79, a deflection system 77, an aperture stop 82, and a lens system 76. The ion source 79 can be a liquid metal ion source (LMIS), for example, it operates using a gallium ion source.

[0169] Ions generated in ion source 79 are accelerated along the optical axis 78 of the ion beam column, focused onto sample 75 by means of objective lens system 80. Ions incident on sample 75 can be used to ablate the material of sample 75 and / or to image sample 75. Microscope system 60 may also optionally have a gas injection system 72 for introducing process gases.

[0170] In addition, the FIB-SEM combination device 60 includes at least one detector 70 for detecting interaction products of electrons and / or ions interacting with the sample 75.

[0171] Furthermore, the microscope system 60 advantageously includes an evaluation and control unit 71. The evaluation and control unit 71 can execute a sequence of control commands contained in a computer program product. By executing the control commands, the microscope system 60 performs an embodiment of the method for setting the tilt angle of a sample according to the invention, such as... Figure 7 As shown in the example.

[0172] Figure 7 A flowchart illustrating a method according to the present invention for tilting a sample by means of a sample holder system is shown schematically.

[0173] First, in step S1, the sample to be examined is provided. The sample is held in the sample chamber of the microscope system used by the sample holder system according to the invention. For this purpose, the sample is received directly on the fourth side surface (upper side surface) of the second rotating element (e.g., Figure 3 (as shown), or if there is another rotating element, then it is received on said rotating element (e.g. Figure 1 (as shown in Figure 2).

[0174] Now, in step S2, the angle β1 is changed by rotating the first rotating element relative to the holder receiving surface of the base element about the rotation axis R1.

[0175] Next, in step S3, the angle β2 is changed by rotating the second rotating element about the rotation axis R2. In this way, the wedge angle α1 of the first rotating element, the wedge angle α2 of the second rotating element, and the two rotation angles β1 and β2 are combined to cause a change in the tilt of the sample relative to the holder receiving surface of the base element. If the holder receiving surface has a specific orientation relative to the optical axis of the microscope system, then the combination of these angles will also cause a change in the tilt of the sample relative to the optical axis.

[0176] In step S4, steps S2 and S3 are repeated until the desired tilt angle of the sample relative to the holder receiving surface is set. In practice, the tilt angle of the sample is typically set relative to one or more optical axes of the microscope system so that the incident angle of the particle beam on the sample can be set in this way.

[0177] In optional step S5, the angle β3 is further changed by rotating the third rotating element about the rotation axis R3. In this way, the sample can be aligned as desired in a plane parallel to the third side surface.

[0178] Particularly advantageous here is that the third rotating element has an upper surface 17 (i.e., the sample receiving surface of the third rotating element) and a lower surface 18, which are arranged parallel to each other, such as... Figure 1 As shown. In this way, the alignment of the sample (i.e., the spatial orientation of the sample in the plane defined by the axes x and y) can be changed without changing the tilt angle of the sample.

[0179] List of reference numerals

[0180] 1 First rotating element

[0181] 2 First side surface (upper side surface of the first rotating element)

[0182] 3. Second side surface (lower side surface of the first rotating element)

[0183] 4. Base plate (base element)

[0184] 5. Holder receiving surface

[0185] 6. Holes in the base element

[0186] 7. Pin-type connectors

[0187] 8 Second Rotating Element

[0188] 9. Third side surface (upper side surface of the second rotating element)

[0189] 10. Fourth side surface (lower side surface of the second rotating element)

[0190] 11 Scale

[0191] 12. Hole in the first rotating element

[0192] 13. Holes in the second rotating element

[0193] 14 Pin-type connectors

[0194] 15 Third Rotating Element

[0195] 16 samples

[0196] 17. Sample receiving surface (upper surface) of the third rotating element

[0197] 18. Side surface (bottom surface) of the third rotating element

[0198] 19 Pin-type connectors

[0199] 20 Sample Holder System

[0200] 21 Sample Holder System

[0201] R1 First axis of rotation

[0202] R2 Second Rotation Axis

[0203] R3 Third axis of rotation

[0204] β1 First rotation angle

[0205] β2 Second rotation angle

[0206] β3 Third rotation angle

[0207] α1 First angle

[0208] α2 Second angle

[0209] α3 Third angle

[0210] θ is the tilt angle of the sample receiving surface (the tilt angle of the sample).

[0211] 60. Microscope System (SEM-FIB Combination Device)

[0212] 61 Electron Beam Column

[0213] 62 electronic sources

[0214] 63 First Condensing Lens System

[0215] Optical axis of 64 electron beam column

[0216] 65 Second Condensing Lens System

[0217] 66-aperture stop

[0218] 67 Deflection System

[0219] 68. Objective Lens System (SEM)

[0220] 69 Sample Chamber

[0221] 70 detectors

[0222] 71 Assessment and Control Unit

[0223] 72 Gas Injection System

[0224] 73 Sample Stage

[0225] 74 Sample Holder System

[0226] 75 samples

[0227] 76 Lens System

[0228] 77 Deflection System

[0229] 78 Optical axis of the ion beam column

[0230] 79 Ion Source

[0231] 80 Objective Lens System (FIB)

[0232] 81 Ion Beam Column

[0233] xx axis

[0234] yy axis

[0235] zz axis

[0236] R Rotation axis

[0237] T-axis

Claims

1. A sample holder system (20, 21) for holding a microscopic sample (16) in a microscope system having at least one optical axis, wherein, The sample holder system (20, 21) includes: - First rotating element (1) and second rotating element (8). -The first rotating element (1) has a first side surface (2) and a second side surface (3), which are opposite to each other and form an angle α1, such that a wedge-shaped cross-section is obtained for the first rotating element (1); and - The second rotating element (8) has a third side surface (9) and a fourth side surface (10), which are arranged opposite to each other and form an angle α2, in such a way that a wedge-shaped cross section of the second rotating element (8) is obtained; -The second rotating element (8) is configured to receive the sample (16) or the third rotating element (15) on the third side surface (9); - and the second rotating element (8) is rotatably connected to the first rotating element (1), wherein the second rotating element (8) has a rotation axis R2 arranged perpendicular to the fourth side surface (10), and the second rotating element (8) is capable of rotating about the rotation axis R2 relative to the first rotating element (1) by a rotation angle β2; - and the first rotating element (1) is configured to be rotatably received on the retainer receiving surface (5), wherein the first rotating element (1) has a rotation axis R1 arranged perpendicular to the second side surface (3), wherein the first rotating element is capable of rotating about the rotation axis R1 relative to the retainer receiving surface (5) by a rotation angle β1. -The inclination of the third side surface (9) of the second rotating element (8) relative to the retainer receiving surface (5) can be set by a combination of these angles α1, α2, β1 and β2; and The fourth side surface (10) and the first side surface (2) are arranged opposite to each other and are aligned parallel to each other in such a way that the rotation axis R2 of the second rotating element (8) is perpendicular to the first side surface (2) of the first rotating element (1).

2. The sample holder system (20) according to claim 1, wherein, The first rotating element (1) is configured such that the second side surface (3) can be received on the retainer receiving surface (5) in such a way that the second side surface (3) and the retainer receiving surface (5) are arranged opposite to each other, wherein the second side surface (3) and the retainer receiving surface (5) are aligned parallel to each other in such a way that the rotation axis R1 of the first rotating element (1) is aligned perpendicular to the retainer receiving surface (5).

3. The sample holder system (20) according to claim 1 or 2, wherein, The sample holder system (20) includes a third rotating element (15) having a sample receiving surface (17) and a side surface (18) arranged opposite to each other. Furthermore, the third rotating element (15) is configured to receive the sample (16) on the sample receiving surface (17) of the third rotating element (15); Furthermore, the third rotating element (15) is rotatably connected to the second rotating element (8), wherein the third rotating element (15) has a rotation axis R3 arranged perpendicular to the side surface (18) of the third rotating element, and the third rotating element (15) is capable of rotating about the rotation axis R3 relative to the second rotating element (8) by a rotation angle β3.

4. The sample holder system (20) according to claim 3, wherein, The side surface (18) of the third rotating element (15) and the third side surface (9) of the second rotating element (8) are arranged opposite each other and aligned parallel to each other, such that the rotation axis R3 is aligned perpendicular to the third side surface (9) of the second rotating element (8).

5. The sample holder system (20, 21) according to claim 3, wherein, The sample holder system (20, 21) includes a base plate (4) that can be mounted on a sample stage, and the base plate (4) has a side surface designed as a holder receiving surface (5).

6. The sample holder system (20, 21) according to claim 3, wherein, These angles α1 and α2 use fixed values, while these angles β1 and β2 are selectable.

7. The sample holder system (20, 21) according to claim 3, wherein, These angles α1 and α2 use values ​​between 0° and 45° and include both 0° and 45°.

8. The sample holder system (20, 21) according to claim 3, wherein, These angles α1 and α2 use different values.

9. The sample holder system (20, 21) according to claim 3, wherein, These rotating elements have a scale (11) for setting the rotation angle β.

10. The sample holder system (20, 21) according to claim 9, wherein, These markings (11) are designed in such a way that they correspond to the mathematical relationship between the desired tilt angle and these wedge angles α and these rotation angles β.

11. The sample holder system (20, 21) according to claim 3, wherein the sample holder system is configured such that it can be received in a microscope system (60) implemented in the form of a particle beam microscope.

12. The sample holder system (20, 21) according to claim 3, wherein, These rotating elements (1, 8, 15) have circular or elliptical bases.

13. A method for setting the tilt angle of a microscopic sample (16, 75) in a microscope system (60) having an optical axis, in, The sample is held by a sample holder system according to any one of claims 3 to 12, and the method includes the following steps: a) The sample is held in place by the sample holder system; b) The rotation angle β1 is changed by rotating the first rotating element about the rotation axis R1; c) By rotating the second rotating element about the rotation axis R2, the rotation angle β2 is changed, and as a result, these angles α1, α2, β1 and β2 are combined to change the inclination of the sample relative to the receiving surface of the holder. d) Repeat steps b) and c) until the sample has the desired tilt relative to the retainer receiving surface.

14. The method according to claim 13, wherein, The method includes the following additional steps: e) The rotation angle β3 is changed by rotating the third rotating element around the rotation axis R3 in such a way that the sample presents the desired orientation in a plane parallel to the third side surface (9).

15. A computer program product comprising a sequence of control commands that causes a microscope system to perform the method for setting the tilt angle of a microscopic sample in a microscope system having an optical axis, as described in claim 13 or 14.

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