JP2011243454A - Electron microscope, sample stage and control method of sample table - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eucentrically tilt a sample table in an arbitrary direction even at a large angle.SOLUTION: An electron microscope 100 includes: a base stage 10 which is movable in X, Y and Z directions; a rotary stage 20 which is arranged rotatably on the base stage 10; a sphere drive stage 30 which is arranged on the rotary stage 20 movably in X and Y directions; a sample tilt drive sphere 40 fitted with a sample table 42 on an upper surface thereof in parallel with the surface, etc., altogether as a sample stage 1 of the electron microscope 100. A controller 70 calculates an X- and Y-directional movement quantities of the sphere drive stage 30 based upon a direction angle and a tilt angle at which the sample table 42 is tilted and a radius of the sample tilt drive sphere 40 so as to move the sphere drive stage 30 by the calculated movement quantities, and further calculates movement quantities of an observation region of a sample 80 in X, Y and Z directions as the sample table 42 is tilted, and moves the base stage 10 by the calculated movement quantities in the opposite directions from the moving directions.

Description

  The present invention relates to an electron microscope, a sample stage, and a sample stage control method capable of tilting a sample stage in a eucentric manner.

When the unevenness of the sample surface is observed in detail with an electron microscope such as SEM (Scanning Electron Microscope), the sample is often tilted and observed from an obliquely upward viewpoint. In this case, if the sample is tilted, the observation target part may be out of the field of view or the focus may be blurred. Therefore, many electron microscope sample stages in recent years are equipped with a function to tilt the sample eucentrically, and even if the sample is tilted, the observation target part may be out of view or out of focus. Is prevented.
Note that eucentric means that the observation target portion does not deviate from the field of view or is out of focus even if the sample is tilted or rotated in an electron microscope or the like.

  Patent Document 1 discloses an example of a eucentric sample stage generally used in an electron microscope or the like. According to Patent Document 1, the sample stage is configured by a holding stage that holds the sample so as to be movable in the X, Y, and R (rotation) directions, and a base stage that holds and tilts the holding stage. Yes. The substrate stage is arranged on the side surface of a cylinder perpendicular to the electron beam irradiation direction and having a straight line intersecting the electron beam irradiation axis as a central axis (hereinafter referred to as the C axis). In addition, it is configured to be rotatable about the C axis along the side surface of the cylinder. The holding stage is held on a surface corresponding to the inside of the cylinder of the base stage.

  In such a sample stage, when the observation target region of the sample held on the holding stage is on the C axis and on the irradiation axis of the electron beam, and the electron beam is in focus. The sample can be tilted eucentrically by rotating the substrate stage around the C axis.

JP 2008-251407 A

  However, in the eucentric sample stage disclosed in Patent Document 1, the substrate stage rotates on the side surface of a large cylinder, so that the size of the vacuum sample chamber for storing the substrate stage becomes large. Alternatively, if the vacuum sample chamber is downsized, the angle at which the substrate stage can be rotated, that is, the sample is tilted due to the balance with other components of the electron microscope, such as the secondary electron detector. The angle that can be made cannot be increased.

  Further, in this case, eucentric tilting is possible only in the direction perpendicular to the C axis. In this case, the user cannot obtain SEM images with different shadows when the sample is viewed from various oblique directions. Of course, even with this sample stage, it is possible to obtain SEM images of the sample viewed from various oblique directions by turning the holding stage back to the horizontal position, rotating it, and tilting it again. It will take extra time.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electron microscope, a sample stage, and a method for controlling the sample stage that can easily and eucentric tilt a sample stage in a given direction even at a large angle.

  In order to achieve the above object, in the electron microscope according to the present invention, the sample stage is disposed in the vacuum sample chamber and freely moves in the X axis, Y axis, and Z axis directions in the chamber. A base stage, and a spherical drive stage that is disposed on the top surface of the base stage, is supported by the top surface of the base stage, and is freely movable in each direction of a plane parallel to the top surface. A sample tilt driving sphere mounted on the upper surface of the sphere driving stage and rotating the upper surface of the mounted sphere driving stage, and a sample stage for holding the sample to be observed. Yes. The sample tilt drive sphere has a predetermined rotation center position above the substrate stage by the substrate stage and a support member supported by the substrate stage and disposed above the sphere drive stage. The sample stage is mounted on the sample tilt drive sphere so that its upper surface is parallel to the surface above the outer surface of the sample tilt drive sphere. It is fixedly arranged.

  In such an electron microscope, when the control device accepts the input of the direction angle and the inclination angle for inclining the sample stage, the control device determines the sphere driving stage based on the direction angle and the inclination angle and the radius of the sample inclination driving sphere. The movement amount in each direction of the X axis and the Y axis is calculated, and the spherical body drive stage is moved by the calculated movement amount. Further, the control device calculates the movement amount in each of the X axis, Y axis, and Z axis directions of the observation target region portion of the sample held on the sample table by inclining the sample table, and the calculated movement The substrate stage is moved in the direction opposite to the moving direction by the amount.

  That is, in the sample stage according to the present invention, by tilting the sample stage, the base stage moves in the opposite direction to the amount of movement of the observation target region portion of the sample in the opposite direction. The part will return to its original position. That is, the eucentric property when the sample is tilted is realized.

  According to the present invention, it is possible to provide an electron microscope, a sample stage, and a sample stage control method capable of easily and eucentrically tilting a sample stage at a large angle in an arbitrary direction.

The figure which showed the example of the structure of the electron microscope which concerns on embodiment of this invention. The figure for demonstrating the eucentric correction movement amount required when a sample stand inclines with the inclination | tilt angle (theta) with respect to the X-axis. The figure for demonstrating the eucentric correction movement amount required when a sample stand inclines in the direction of the direction angle (gamma) by inclination-angle (theta). The figure which showed the example of the process sequence of the eucentric stage control performed with the control apparatus of the electron microscope which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing an example of the configuration of an electron microscope according to an embodiment of the present invention. As shown in FIG. 1, an electron microscope 100 is a so-called SEM, and a sample stage 1 (sample stage) for holding and moving a mirror body 50 including an electron gun 50a, an electron lens 50b, and a sample 80 to be observed. 42, a sphere driving stage 30, a substrate stage 10, etc.), a vacuum sample chamber 60 for storing the sample stage 1, and a control device 70 for acquiring an observation image of the sample 80 by controlling the mirror 50 and the sample stage. , Including.

  Here, the sample 80 is held on the upper surface of the sample stage 42, and the observation target region portion is irradiated with the electron beam 51 emitted from the objective lens portion of the electron lens 50b of the mirror body 50. From the surface of the sample 80 irradiated with the electron beam 51, secondary electrons 52 corresponding to the material and shape of the surface are emitted. The secondary electron detector 53 detects the emitted secondary electrons 52, converts the detected amount of the secondary electrons 52 into an electric signal or the like, and transmits it to the control device 70 as a secondary electron detection signal.

  The control device 70 is configured by a computer including at least a CPU (Central Processing Unit) 71 and a memory 72, and includes a signal processing unit 73, a mirror body control unit 74, a stage control unit 75, and the like. Here, the signal processing unit 73 receives the secondary electron detection signal transmitted from the secondary electron detector 53. Then, the received secondary electron detection signal is synchronized with the scanning control signal of the electron beam 51 output from the mirror control unit 74 to the mirror 50, and a two-dimensional observation image of the surface of the sample 80 is generated. The generated two-dimensional observation image is stored in the memory 72. The CPU 71 reads out the two-dimensional observation image stored in the memory 72 and displays it on the display unit 76.

  In the present embodiment, in order to obtain a two-dimensional observation image obtained by viewing the surface of the sample 80 obliquely from above, the sample stage 42 that holds the sample 80 is above the normal direction of the surface of the sample tilt drive sphere 40. It is attached via the support member 41 so as to be parallel to the surface (that is, parallel to the tangential plane of the sphere). That is, the sample stage 42 is mounted on the sample tilt drive sphere 40 so that the upper surface thereof is perpendicular to the straight line connecting the center of the sample tilt drive sphere 40 and the center of the sample stage 42. Therefore, by rotating the sample tilt driving sphere 40 in an arbitrary direction at an arbitrary angle, the sample stage 42, that is, the sample 80 can be easily tilted in an arbitrary direction by an arbitrary tilt angle.

  Here, the sample tilt driving sphere 40 is placed on the horizontal upper surface of the sphere driving X stage 31 and can freely roll, that is, rotate without sliding on the upper surface. The sample stage 42 is configured to rotate integrally with the sample tilt drive sphere 40. At this time, as materials for the sample tilt driving sphere 40 and the sphere driving X stage 31, a material having a sufficiently large sliding friction between the surfaces thereof is selected. As a result, when the sample tilt drive sphere 40 rolls on the upper surface of the sphere drive X stage 31, the sample stage 42 tilts according to the rolling direction and distance.

  Therefore, in this embodiment, the center position of the sample tilt driving sphere 40 is fixed, and the sphere driving X stage 31 is configured to be freely movable by an appropriate distance in an arbitrary horizontal direction. Then, the user rotates the sample tilt driving sphere 40 by moving the sphere driving X stage 31 in an appropriate direction by an appropriate distance, and tilts the sample stage 42 in a desired direction by a desired angle. Will be able to.

  First, a configuration in which the sphere drive X stage 31 is freely movable by an appropriate distance in an arbitrary direction (horizontal direction) will be described. As shown in FIG. 1, the sphere drive X stage 31 is disposed on the horizontal upper surface of the sphere drive Y stage 32 so as to be movable in the X direction, and the sphere drive Y stage 32 is a horizontal upper surface of the rotary stage 20. Are arranged to be movable in the Y direction. For example, the sphere drive X stage 31 is configured as a stage that moves only in the X direction along the rail on the X direction rail provided on the upper surface of the sphere drive Y stage 32, and the sphere drive Y stage 32. Is configured as a stage that moves on the rail in the Y direction provided on the upper surface of the rotary stage 20 only in the Y direction along the rail.

  The sphere drive X stage 31 and the sphere drive Y stage 32 configured in this way are stages that move substantially freely in the X and Y directions on the horizontal upper surface of the rotary stage 20 in an integrated manner. Hereinafter, these stages are collectively referred to as a sphere driving stage 30 in the book. That is, the spherical body drive stage 30 can freely move in the X and Y directions on the upper surface of the rotary stage 20.

  In FIG. 1, the X-axis direction is the horizontal direction, the direction from the left to the right of the page, the Y-axis direction is the horizontal direction, the direction from the front side to the back side of the page, and the Z-axis direction is the vertical direction. The direction from the bottom to the top of the page. In the present specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are simply referred to as the X direction, the Y direction, and the Z direction, respectively.

  Next, a configuration for fixing the center position of the sample tilt driving sphere 40 on the rotary stage 20 will be described. As shown in FIG. 1, the configuration is realized by a sphere holding member 22 and a connection member 21 that fixes the sphere holding member 22 to the rotary stage 20 while being separated.

  That is, the sphere holding member 22 is a plate member having an opening having a diameter slightly smaller than the diameter of the sample tilt driving sphere 40 at the center thereof, and is in contact with the sample tilt driving sphere 40 on the inner wall side of the opening. A bearing 23 is provided. The sphere holding member 22 accommodates the sample tilt driving sphere 40 below the opening, and sandwiches the accommodated sample tilt driving sphere 40 between the sphere holding member 22 and the upper surface of the sphere driving X stage 31. In this manner, the center position of the sample tilt drive sphere 40 is fixed. At this time, since the bearing 23 is provided on the inner wall side of the opening of the sphere holding member 22, the sample tilt driving sphere 40 can rotate smoothly within the opening of the sphere holding member 22.

  Next, the rotary stage 20 is disposed on the horizontal upper surface of the base X stage 11 so as to be rotatable in the horizontal plane. The rotary stage 20 is also a stage that is generally provided in a normal electron microscope. That is, when the sample stage 42 is held horizontally via the sample tilt drive sphere 40 and the support member 41, the rotary stage 20 moves the sample stage 42 and the sample 80 held on the upper surface thereof in an arbitrary horizontal direction. Have a role to rotate.

  In the present embodiment, when the spherical body holding member 22 is attached to the rotary stage 20 by the connecting member 21, the center of the opening is attached so as to substantially coincide with the rotational axis of the rotary stage 20. .

  Next, the sphere driving stage 30 is moved when the focal position of the electron beam 51 irradiated from the mirror 50 is aligned with the observation target region portion of the sample 80 with the sample stage 42 kept horizontal. Thus, it is considered that the sample tilt driving sphere 40 is rotated and the sample stage 42 is tilted. In that case, when the rotary stage 20 is stationary with respect to the mirror body 50, when the sample tilt drive sphere 40 rotates and the sample stage 42 tilts, the observation target region portion of the sample 80 moves with the tilt. Therefore, the focal position of the electron beam 51 deviates.

  Therefore, in the present embodiment, when the sample tilt drive sphere 40 rotates and the sample stage 42 tilts so that the observation target region portion of the sample 80 moves from the focal position of the electron beam 51, the movement amount In the same direction, the entire rotation stage 20 mounted with the sample stage 42 and the like is moved in the opposite direction so that the observation target region portion of the sample 80 is returned to the original position. Then, even if the sample stage 42 is tilted, the relative positional relationship between the observation target region of the sample 80 and the focal position of the electron beam 51 does not change, so that the eucentricity is realized.

  In this case, the entire rotary stage 20 is moved by the base X stage 11 on which the rotary stage 20 is disposed. Here, the substrate X stage 11 is disposed on the horizontal upper surface of the substrate Y stage 12 so as to be movable in the X direction, and the substrate Y stage 12 is movable on the horizontal upper surface of the substrate Z stage 13 in the Y direction. Further, the base Z stage 13 is disposed on the inner wall of the housing of the vacuum sample chamber 60 so as to be movable in the Z direction. Therefore, the rotary stage 20 is freely moved in the X, Y, and Z directions by appropriately moving the base X stage 11, the base Y stage 12, and the base Z stage 13 in the X, Y, and Z directions, respectively. be able to.

  As described above, the base X stage 11, the base Y stage 12, and the base Z stage 13 are stages that move in the X, Y, and Z directions within the housing of the vacuum sample chamber 60 substantially integrally. In the present specification, these stages are hereinafter collectively referred to as a base stage 10. That is, the substrate stage 10 is a stage that can freely move in the X, Y, and Z directions within the housing of the vacuum sample chamber 60.

  The substrate stage 10 is not a stage newly provided to ensure eucentricity when the specimen 80 is tilted, but is a stage generally provided in a normal electron microscope, like the rotary stage 20. The substrate stage 10 is usually used for positioning and focusing of the observation target region of the sample 80.

  Note that the driving of the sample stage 1 such as the substrate stage 10 described above is normally performed by a stage driving unit 65 provided outside the vacuum sample chamber 60. The stage drive unit 65 includes a motor that serves as a driving power source, a mechanism unit that supports and moves the substrate stage 10, and the like. In addition, although the drive part of the rotation stage 20 and the spherical body drive stage 30 will be arrange | positioned on each stage in the vacuum sample chamber 60, the illustration is abbreviate | omitted here.

  In the above description, it is implicitly assumed that the X-axis direction and the Y-axis direction in which the sphere driving stage 30 moves are the same as the X-axis direction and the Y-axis direction in which the substrate stage 10 moves. However, in the present embodiment, since the rotary stage 20 exists, generally, the assumption does not hold. However, in the present embodiment, since it is not substantially assumed that the rotary stage 20 rotates, the coordinate system based on the moving direction of the sphere driving stage 30 and the moving direction of the substrate stage 10 are also described in the following description. Assume that the coordinate systems based on are the same. A case where the coordinate systems of both are different will be described supplementarily at the end.

  Next, with reference to FIG. 2 and FIG. 3, a calculation formula for the amount of movement by which the substrate stage 10 should be moved in order to ensure eucentricity when the sample stage 42 is tilted will be described. Note that the components in the X direction, Y direction, and Z direction of the movement amount are represented by (δX, δY, δZ), and are hereinafter referred to as eucentric correction movement amounts.

  FIG. 2 is a diagram for explaining the eucentric correction moving amount required when the sample stage 42 is inclined at the inclination angle θ with respect to the X axis. Here, as shown in FIG. 2, a point where the sample tilt driving sphere 40 is in contact with the upper surface of the sphere driving X stage 31 is defined as an origin O. A straight line (indicated by a solid line with an arrow) passing through the origin O and included in the upper surface of the sphere drive X stage 31 and parallel to the moving direction of the sphere drive X stage 31 is defined as the X axis. A straight line (indicated by an alternate long and short dash line with an arrow) that passes through the origin O and the center Q of the sample tilt drive sphere 40 and is perpendicular to the X axis is taken as the Z axis. A straight line (not shown) that is included in the upper surface of the sphere-driven X stage 31 and is perpendicular to the X axis (passes through the origin O and goes from the front side to the back side of the paper) is defined as the Y axis.

  Further, the position before tilt driving of the observation target region portion of the sample 80 held on the upper surface of the sample table 42 (not shown) supported on the sample tilt driving sphere 40 by the support member 41 is represented by a point A. Further, the distance from the point A to the center Q of the sample tilt driving sphere 40 is represented by the symbol a, and the radius of the sample tilt driving sphere 40 is represented by the symbol b.

When the sphere driving X stage 31 is driven in the positive direction of the X axis and the sample stage 42 is tilted by the tilt angle θ, the position of the observation target region moves from the point A to the point A ′. At this time, the driving amount s for driving the sphere driving X stage 31 in the positive direction of the X axis is:
s = −b · θ
Given by.

That is, when the sphere drive X stage 31 is moved by the distance s in the negative direction of the X axis, the sample stage 42, that is, the sample 80 is inclined by the inclination angle θ. The coordinates (x, y, z) of the point A ′ at this time are (a · sin θ, 0, b + a · cos θ). Therefore, at this time, the movement amount (ΔX, ΔY, ΔZ) by which the point A moves to the point A ′ is
(ΔX, ΔY, ΔZ) = (a · sin θ, 0, a · cos θ−a)
Given in.

Accordingly, the eucentric correction movement amount (δX, δY, δZ) of the substrate stage 10 is
(ΔX, δY, δZ) = (− a · sin θ, 0, a−a · cos θ)
It becomes. That is, after the sample stage 42 is inclined with respect to the Z axis by an inclination angle θ, the substrate stage 10 is moved by a distance of −a · sin θ in the positive direction of the X axis, and aa · in the positive direction of the Z axis. If it is moved by the distance of cos θ, the point A ′ in the observation target area portion returns to the original point A, and eucentricity with respect to the inclination of the observation target area portion is ensured.

  FIG. 3 is a diagram for explaining the eucentric correction moving amount required when the sample stage 42 is inclined at the inclination angle θ in the direction of the direction angle γ. FIG. 3 is a diagram in which a two-dimensional description is generalized to a three-dimensional description by introducing a direction angle γ representing the direction in which the sample stage 42 is inclined in the configuration of FIG. . Accordingly, the coordinate axes are taken in the same way as in FIG. 2, but the way of illustration is that FIG. 2 is a cross-sectional view on the Y = 0 plane, while FIG. 3 is a perspective view. Is different in that

In FIG. 3, a point P is a projection point of the point A ′ onto the XY plane (Z = 0 plane). At this time, the direction angle γ is defined as an angle formed by the line segment OP and the X axis. Further, the inclination angle θ corresponds to an angle formed by the line segment QA ′ with the Z axis. Therefore, since the length of the line segment OP is given by a · sin θ, the coordinates (x, y) of the point P are
(X, y) = (a · sinθ · cosγ, a · sinθ · sinγ)
It becomes.

Therefore, in the case of FIG. 3, the movement amounts (ΔX, ΔY, ΔZ) by which the observation target region portion of the sample 80 moves from the point A (not shown in FIG. 3) to the point A ′ are
(ΔX, ΔY, ΔZ) =
(A · sinθ · cosγ, a · sinθ · sinγ, a · cosθ-a)
Given in. Therefore, the eucentric correction moving amount (δX, δY, δZ) of the substrate stage 10 is
(ΔX, δY, δZ) =
(-A · sinθ · cosγ, -a · sinθ · sinγ, aa · cosθ)
It becomes.

In this case, the driving amount s of the sphere driving stage 30 is s = −b · θ as in the case of FIG.
The respective X-direction component sx and Y-direction component sy are given by
(Sx, sy) = (− b · θ · cos γ, −b · θ · sin γ)
It becomes.

  Thus, the driving distance s of the sphere driving stage 30 is given. In this case, it should be noted that when the sphere driving X stage 31 and the sphere driving Y stage 32 of the sphere driving stage 30 are driven, the sample tilt driving sphere 40 is driven. This means that the locus of the contact when rotating the upper surface of the sphere drive X stage 31 must be a straight line. Otherwise, the observation target area portion of the sample 80 cannot be correctly moved to the point A ′ by using the previously determined driving amount s (sx, sy).

In order for the locus of contact when the sample tilt driving sphere 40 rolls on the upper surface of the sphere driving X stage 31 to be a straight line, the moving speed of the sphere driving X stage 31 and the moving speed of the sphere driving Y stage 32 are It is necessary that the ratio is always constant. Therefore, in this embodiment, when the respective target speeds are (Vx, Vy),
(Vx, Vy) = (− b · θ · cosγ / Δt, −b · θ · sinγ / Δt)
The sphere driving X stage 31 and the sphere driving Y stage 32 are driven at the moving speed given by.

  Here, Δt is a numerical value that should be set before calculating (Vx, Vy). Here, for example, when Va is the maximum speed that can be taken on average by the sphere drive X stage 31 and the sphere drive Y stage 32, Δt is b · θ · cos γ / Va, b · θ · sin γ / Va. Of these, the larger value is assumed.

  FIG. 4 is a diagram illustrating an example of a processing procedure of eucentric stage control performed by the control device 70 of the electron microscope 100 according to the embodiment of the present invention. As shown in FIG. 1, the CPU 71 and the stage control unit 75 of the control device 70 drive the base stage 10, the rotary stage 20, and the spherical body drive stage 30 via the stage drive unit 65.

  First, the CPU 71 obtains the tilt angle θ and the direction angle γ of the sample 80 (sample stage 42) desired by the user from an input device such as a keyboard (not shown) (step S11). Next, based on the acquired tilt angle θ and direction angle γ and the radius b of the sample tilt drive sphere 40, the CPU 71 moves the distance s (s = s = s) where the sample tilt drive sphere 40 rolls on the upper surface of the sphere drive X stage 31. -B · θ) is calculated (step S12). Further, the CPU 71 calculates the movement amount (Δx, Δy) of the sphere driving stage 30 based on the distance s and the direction angle γ (step S13). Here, Δx = −s · cos γ and Δy = −s · sin γ.

  Next, the CPU 71 calculates a target moving speed (Vx, Vy) of the sphere driving stage 30 for the sample tilt driving sphere 40 to roll linearly on the upper surface of the sphere driving X stage 31 (step S14). Here, Vx = −s · cos γ / Δt, Vy = −s · sin γ / Δt, where Δt is, for example, b · θ · cos γ / Va, b · θ · sin γ / It is assumed that Va is the larger value.

  Next, the CPU 71 instructs the stage driving unit 65 via the stage control unit 75 to move the sphere driving stage 30 by the moving amount (Δx, Δy) at the target moving speed (Vx, Vy) (step). S15). Based on this instruction, the stage drive unit 65 moves the sphere drive stage 30, and as a result, the sample 80 (sample stage 42) is inclined at the inclination angle θ in the direction of the direction angle γ.

Next, the CPU 71 calculates the movement amount (ΔX, ΔY, ΔZ) of the observation target region portion of the sample 80 based on the movement of the sphere driving stage 30 (step S16). here,
ΔX = a · sin θ · cos γ, ΔY = a · sin θ · sin γ, ΔZ = a · cos θ−a
It is.

  Next, the CPU 71 instructs the stage driving unit 65 to move the substrate stage 10 by the movement amount (−ΔX, −ΔY, −ΔZ) (step S17). Based on this instruction, the stage drive unit 65 moves the substrate stage 10 by the movement amounts (−ΔX, −ΔY, −ΔZ), and therefore the sample 80 (sample stage 42) is driven to tilt in the observation target region. Return to the same position as before. As a result, eucentricity with respect to the inclination of the observation target region is ensured.

  In the above description using FIG. 3 and FIG. 4, the eucentric correction moving amount (δX, δY, δZ) of the base stage 10 is calculated based on the coordinate axis in the sphere driving stage 30. Accordingly, when the XY coordinate system based on the moving direction of the substrate stage 10 is rotated by an arbitrary angle β with respect to the XY coordinate system based on the sphere driving stage 30, the eucentric corrected moving amount (δX , ΔY, δZ) must be calculated in the XY coordinate system based on the substrate driving stage 10.

Therefore, it is assumed that the XY coordinate system based on the base stage 10 is obtained by rotating the XY coordinate system based on the sphere driving stage 30 by an angle β. In that case, the coordinates (x ′, y ′) of the point P, which is the projection point of the point A ′ in FIG.
(X ′, y ′) = (a · sin θ · cos (γ−β), a · sin θ · sin (γ−β))
It becomes.
Accordingly, δX and δY of the eucentric correction moving amount (δX, δY, δZ) based on the XY coordinate system in the substrate stage 10 are
δX = −a · sin θ · cos (γ−β)
δY = −a · sinθ · sin (γ−β)
As can be easily obtained.

  As described above, according to the present embodiment, the sample stage 42, that is, the sample 80, is provided by providing the sphere driving stage 30 and the sample tilt driving sphere 40 on the base stage 10 and the rotary stage 20 that have been conventionally used. It is possible to incline at an arbitrary inclination angle θ in an arbitrary direction angle γ. Further, since the position movement of the observation target region of the sample 80 accompanying the tilt can be canceled by the movement of the substrate stage 10, the eucentricity when the sample stage 42 is tilted can be realized.

  In the present embodiment, the direction angle γ is allowed to be any angle from 0 to 360 degrees. On the other hand, even if the inclination angle θ is arbitrary, it is necessary to dispose the support member 41 slightly above the horizontal plane passing through the center of the sample inclination driving sphere 40 to hold the sample inclination driving sphere 40. The maximum inclination angle is limited to about 80 degrees. However, 80 degrees is a sufficiently large inclination angle for practical use, and there is no particular problem.

  Moreover, in the eucentric stage described in Patent Document 1, the stage that tilts the sample eucentrically holds a general moving stage that moves the sample in the X, Y, and Z directions. On the other hand, in this embodiment, a stage (a sphere drive stage 30, a sample tilt drive sphere 40, etc.) that tilts the sample 80 (sample stage 42) moves the sample 80 in the R, X, Y, and Z directions. It is configured to be held by a typical stage (base stage 10). Moreover, the eucentricity when the sample 80 is tilted is realized by using the substrate stage 10. Accordingly, it is easier to reduce the stage size of the sample stage 1 in the present embodiment than the eucentric stage described in Patent Document 1. Therefore, the size of the vacuum sample chamber 60 can be reduced.

  The embodiment described above relates to the electron microscope 100 such as an SEM and the sample stage 1 used in the electron microscope 100, but the description thereof is applied to an ion beam processing apparatus (FIB (Focused Ion Beam) processing apparatus). However, the present invention is applicable to the ion beam processing apparatus and its sample stage.

DESCRIPTION OF SYMBOLS 1 Sample stage 10 Base | substrate stage 11 Base | substrate X stage 12 Base | substrate Y stage 13 Base | substrate Z stage 20 Rotation stage 21 Connection member 22 Sphere holding member 23 Bearing 30 Sphere drive stage 31 Sphere drive X stage 32 Sphere drive Y stage 40 Sample inclination drive sphere 41 Support member 42 Sample stage 50 Mirror body 50a Electron gun 50b Electron lens 51 Electron beam 52 Secondary electron 53 Secondary electron detector 60 Vacuum sample chamber 65 Stage drive unit 70 Controller 71 CPU
72 Memory 73 Signal Processing Unit 74 Mirror Control Unit 75 Stage Control Unit 76 Display Unit 80 Sample 100 Electron Microscope

Claims (9)

A mirror including an electron gun and an electron lens, a sample stage for holding a sample, a vacuum sample chamber for storing the sample stage, and a control device for controlling the operation of the sample stage An electron microscope,
The sample stage is
A substrate stage disposed in the vacuum sample chamber and freely moving in the X-axis, Y-axis, and Z-axis directions in the chamber;
A sphere driving stage that is supported on the upper surface of the substrate stage and moves freely in each direction of the X axis and the Y axis within a plane parallel to the upper surface;
A sample tilt driving sphere mounted on the upper surface of the sphere driving stage and rotating the upper surface of the mounted sphere driving stage;
A sample stage for holding the sample to be observed;
Comprising
The sample tilt drive sphere is:
The base stage and a support member supported by the base stage and disposed above the spherical body driving stage are held so that their rotation center position is fixed at a predetermined position above the base stage. And
The sample stage is
Above the outer surface of the sample tilt drive sphere, arranged fixed to the sample tilt drive sphere so that its upper surface is parallel to the surface,
The controller is
When an input of a direction angle and an inclination angle for inclining the sample stage is received, based on the direction angle, the inclination angle, and the radius of the sample inclination driving sphere, the X axis and Y axis directions of the sphere driving stage are determined. Calculate the movement amount, move the spherical drive stage by the calculated movement amount,
Calculate the amount of movement in each of the X-axis, Y-axis, and Z-axis directions of the observation target region portion of the sample held on the sample table by inclining the sample table, and only the calculated movement amount An electron microscope characterized in that the substrate stage is moved in a direction opposite to the moving direction. The sample stage further includes a rotation stage,
The rotary stage is
The upper surface of the substrate stage is rotatably supported in a plane parallel to the upper surface, and is disposed.
The spherical drive stage is
The electron microscope according to claim 1, wherein the electron microscope is disposed on an upper surface of the rotary stage so as to be movable in each direction of the X axis and the Y axis on the upper surface. The controller is
When the sphere driving stage is moved, the X axis direction and the Y axis direction are moved so that the locus of the point in contact with the upper surface of the sphere driving stage draws a straight line when the sample tilt driving sphere rotates. The electron microscope according to claim 1, wherein the sphere driving stage is moved by adjusting a speed. A mirror including an electron gun and an electron lens, a sample stage for holding a sample, a vacuum sample chamber for storing the sample stage, and a control device for controlling the operation of the sample stage A sample stage in an electron microscope,
A substrate stage disposed in the vacuum sample chamber and freely moving in the X-axis, Y-axis, and Z-axis directions in the chamber;
A sphere driving stage that is supported on the upper surface of the substrate stage and moves freely in each direction of the X axis and the Y axis within a plane parallel to the upper surface;
A sample tilt driving sphere mounted on the upper surface of the sphere driving stage and rotating the upper surface of the mounted sphere driving stage;
A sample stage for holding the sample to be observed;
Comprising
The sample tilt drive sphere is:
The base stage and a support member supported by the base stage and disposed above the spherical body driving stage are held so that their rotation center position is fixed at a predetermined position above the base stage. And
The sample stage is
Above the outer surface of the sample tilt drive sphere, arranged fixed to the sample tilt drive sphere so that its upper surface is parallel to the surface,
When the control device receives an input of a direction angle and an inclination angle for inclining the sample stage,
The spherical drive stage is
The control device moves according to the movement amount in each direction of the X axis and the Y axis calculated based on the direction angle, the inclination angle, and the radius of the sample inclination driving sphere,
Thereafter, the base stage is
The X-axis, Y-axis, and Z-axis directions of the observation target region portion of the sample held on the sample stage as the sphere driving stage moves and the sample stage tilts as calculated by the control device A sample stage characterized by moving in the direction opposite to the moving direction by the same moving amount as the moving amount. The sample stage further includes a rotation stage,
The rotary stage is
The upper surface of the substrate stage is rotatably supported in a plane parallel to the upper surface, and is disposed.
The spherical drive stage is
5. The sample stage according to claim 4, wherein the sample stage is disposed on the upper surface of the rotary stage so as to be movable in each direction of the X axis and the Y axis on the upper surface. When the sphere drive stage moves,
The X-axis direction and the Y-axis direction are adjusted so as to move so that a locus of a point in contact with the upper surface of the sample tilting drive sphere rotates in a straight line. The sample stage according to claim 4 or 5. A mirror including an electron gun and an electron lens, a sample stage for holding a sample, a vacuum sample chamber for storing the sample stage, and a control device for controlling the operation of the sample stage A method for controlling a sample stage in an electron microscope,
The sample stage is
A substrate stage disposed in the vacuum sample chamber and freely moving in the X-axis, Y-axis, and Z-axis directions in the chamber;
A sphere driving stage that is supported on the upper surface of the substrate stage and moves freely in each direction of the X axis and the Y axis within a plane parallel to the upper surface;
A sample tilt driving sphere mounted on the upper surface of the sphere driving stage and rotating the upper surface of the mounted sphere driving stage;
A sample stage for holding the sample to be observed;
Comprising
The sample tilt drive sphere is:
The base stage and a support member supported by the base stage and disposed above the spherical body driving stage are held so that their rotation center position is fixed at a predetermined position above the base stage. And
The sample stage is
Above the outer surface of the sample tilt drive sphere, arranged fixed to the sample tilt drive sphere so that its upper surface is parallel to the surface,
The controller is
When an input of a direction angle and an inclination angle for inclining the sample stage is received, based on the direction angle, the inclination angle, and the radius of the sample inclination driving sphere, the X axis and Y axis directions of the sphere driving stage are determined. Calculate the movement amount, move the spherical drive stage by the calculated movement amount,
Calculate the amount of movement in each of the X-axis, Y-axis, and Z-axis directions of the observation target region portion of the sample held on the sample table by inclining the sample table, and only the calculated movement amount A method for controlling a sample stage, wherein the substrate stage is moved in a direction opposite to the moving direction. The sample stage further includes a rotation stage,
The rotary stage is
The upper surface of the substrate stage is rotatably supported in a plane parallel to the upper surface, and is disposed.
The spherical drive stage is
The sample stage control method according to claim 7, wherein the sample stage is disposed on an upper surface of the rotary stage so as to be movable in each direction of the X axis and the Y axis on the upper surface. The controller is
When the sphere driving stage is moved, the X axis direction and the Y axis direction are moved so that the locus of the point in contact with the upper surface of the sphere driving stage draws a straight line when the sample tilt driving sphere rotates. The sample stage control method according to claim 7 or 8, wherein the sphere driving stage is moved by adjusting a speed.

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