JP3702685B2 - Charged particle beam equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a side entry sample stage for a charged particle beam apparatus, and more particularly to a charged particle beam apparatus having a eucentric sample stage.
[0002]
[Prior art]
A eucentric side entry sample stage used in a conventional charged particle beam apparatus will be described with reference to FIGS.
[0003]
A sample stage is provided on the side surface of the objective lens composed of the upper magnetic pole 1a and the lower magnetic pole 1b. This sample stage is attached to the side wall of the mirror body 3. The holding cylinder 5 is rotatably mounted via a bearing 9 inside the support cylinder 4 fixed to the side wall so that the X axis orthogonal to the optical axis (Z axis) of the electron beam 2 is the center of rotation.
[0004]
An inclined cylinder 6 into which a sample holder 7 can be inserted is attached in the holding cylinder 5. The inclined cylinder 6 has a spherical bearing 6a having a fulcrum center on the X axis, and is attached rotatably. The inclined cylinder 6 is supported in the Z direction by a knob 10 attached to the holding cylinder 5 and moved in the Z direction, a pin 11 and a spring 12. The Y direction is supported by a driving machine 17 attached to the holding cylinder 5 and moved in the Y direction, a pin 18 and a spring 19.
[0005]
A driving machine 16 is attached to the outside of the holding cylinder 5 and connected so that the holding cylinder 5 can be rotated. The sample holder 7 is provided with a sample mounting portion 7a where the optical axis and the holder axis coincide with each other, and the sample 8 is mounted thereon.
[0006]
A drive unit 15 and a drive rod 14 in the X-axis direction are attached to a position facing the inclined cylinder 6 on the X-axis, and are connected to the sample holder 7 via the movable body 13. The floating body 13 has a pivot and pivot bearing structure at the joint between the sample holder 7 and the drive rod 14 and is rotatable.
[0007]
Each drive unit that drives the stage is controlled by a stage controller.
The stage controller has means for registering or detecting the movement limit values of the X-axis, Y-axis, (Z-axis), and tilt angle of the sample, and controls the drive device within the movement limit range.
[0008]
In the apparatus having such a configuration, the sample holder 7 is drawn into the inside of the mirror body because the inside of the body with the objective lens is vacuum, and always pushes the floating body 13 in the direction of the driving machine 15. Thus, the sample holder 7 can be moved in the X-axis direction via the movable body 13 by moving the drive rod 14 in the X-axis direction. Thus, the sample 8 can be moved in the X-axis direction.
[0009]
Further, if the tilting cylinder 6 is moved in the Y-axis direction by the driving machine 17, the sample holder 7 rotates in the Y-axis direction with the spherical bearing 6a as a fulcrum, so that the sample 8 can move in the Y-direction. Similarly, if the tilt cylinder 6 is moved in the Z-axis direction with the knob 10, the sample holder 7 rotates in the Z direction with the spherical bearing 6a as a fulcrum, so that the sample 8 can move in the Z-axis direction. Further, if the holding cylinder 5 is rotated by the driving machine 16, the holding cylinder 5 rotates around the X axis while holding the inclined cylinder 6, so that the sample 8 can be inclined as shown in FIG. By these moving mechanisms, the observation surface of the sample 8 is controlled so that it is always located at the origin of the X, Y, and Z axes.
[0010]
[Problems to be solved by the invention]
With advances in semiconductor technology, there has been a growing need for an in-lens scanning electron microscope that can narrow the electron beam and obtain a sample image with high resolution. In particular, in an in-lens scanning electron microscope in which a sample is disposed between an upper magnetic pole and a lower magnetic pole of an objective lens, the size of the sample to be observed is greatly limited, and a sample of several millimeters square must be made.
[0011]
The procedure for preparing this sample will be described with reference to FIG. In order to create the sample 27 (length L, width H) from the wafer 25, first the wafer 26 is cut into a width H and then cut into a length L. However, since this operation is performed manually, it is not easy to cut out into several millimeters. As shown in FIGS. 9 and 10, in order to perform cross-sectional observation, it is necessary to cut the width H to about 3 to 4 mm, which is a very difficult operation. For this reason, an apparatus capable of mounting a larger sample is desired.
[0012]
On the other hand, high-resolution sample images are required for charged particle beam devices. One method for increasing the resolution is to bring the sample observation surface closer to the upper magnetic pole lower surface.
[0013]
However, when trying to solve these problems with a conventional eucentric side-entry sample stage, there is a method in which only the sample observation surface 8a is positioned above the axis of the holder 7 as shown in FIG. Since the tilt center is on the X axis, when tilted as shown in FIG. 13, the sample observation surface 8a is greatly displaced, and the position control of the stage becomes very complicated. On the other hand, as a method of increasing the resolution, there is a method of bringing the sample holder 7 close to the upper magnetic pole 1a as shown in FIG. 14, but the member of the sample mounting portion 7a interferes with the upper magnetic pole 1a as shown in FIG. In addition, the inclination angle Θ becomes small.
[0014]
The present invention solves the above-described problems, and in particular makes it possible to handle a larger sample in a charged particle beam apparatus that employs a side entry type sample holder having an inclination function that greatly restricts a space for arranging the sample. It is another object of the present invention to provide a charged particle beam apparatus suitable for obtaining a sample image with high resolution.
[0015]
[Means for Solving the Problems]
In order to solve the above problem, in the present invention, in a charged particle beam apparatus including a charged particle source and a charged particle beam mirror containing an objective lens for converging a charged particle beam generated from the charged particle source. A sample holder inserted from a side of the charged particle beam mirror and supporting a sample irradiated to the charged particle beam; an insertion opening for the sample holder to be inserted; and the sample holder for the charged particle beam A sample holder support cylinder having an inclination mechanism that is inclined with respect to the sample holder, and the insertion opening of the sample holder is provided eccentrically in the irradiation direction of the charged particle beam with respect to the inclination center of the sample holder support cylinder. Provided is a charged particle beam device.
[0016]
By providing such a charged particle beam apparatus, it is possible to observe a large sample piece while maintaining a large tilt angle, and to obtain a sample image with higher resolution.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The sample holder inserted into the sample stage slides in the X-axis direction, rotates in the Y-axis and Z-axis directions with a spherical bearing as a fulcrum, and is further eccentric in the Z-axis direction from the rotation axis of the holding cylinder. Rotating motion in the state. For this reason, the sample moves in the X-axis, Y-axis, and Z-axis directions and tilts around the X-axis.
[0018]
Further, the movement range of the X axis, Y axis, (Z axis), and tilt angle is found from the input value, and the movement range of the sample is limited.
[0019]
Embodiments of the present invention will be described below with reference to FIGS. 7 to 15 indicate the same components.
[0020]
FIG. 1 is an XZ sectional view of a side entry sample stage. 2 and 3 are detailed sectional views of the sample mounting portion. In the holding cylinder 5, an inclined cylinder 6 in which the sample holder insertion hole is eccentric in the Z-axis direction is disposed. The inclined cylinder 6 is provided with a spherical bearing 6 a having a fulcrum center on the rotation axis (X axis in the figure) of the holding cylinder 5 and is attached to the mirror body 3. The sample holder 7 on which the sample 8 is mounted is inserted into the inclined cylinder 6 and connected to the floating body 13.
[0021]
The sample holder provided in the sample holder 7 is formed in a concave shape along the optical axis as shown. The width of the recesses may set larger Ri thickness Saya semiconductor wafer, for example. This is because the sample piece cut out for the cross-sectional observation shown above is inserted and observed.
[0022]
In the embodiment device of the present invention, the distance between the bottom of the recess and the rotating shaft of the holding cylinder 5 can be increased. That is, as compared with the conventional technique, the sample piece can be cut out largely, so that the preparation of the observation sample is facilitated without requiring fine processing.
[0023]
Further, the apparatus according to the present invention employs a so-called in-lens type objective lens in which a sample is disposed between the upper magnetic pole 1a and the lower magnetic pole 1b of the objective lens, and the space for inserting the sample holder is extremely limited. However, this limited space can be used effectively for the arrangement of the sample pieces.
[0024]
Here, if the driving rod 14 is moved by the X-axis direction driving machine 15, the sample holder 7 slides in the X-axis direction, so that the sample 8 moves in the X-axis direction. If the tilting cylinder 6 is moved in the Y-axis direction by the Y-axis direction drive 17, the sample holder 7 rotates in the Y-axis direction with the spherical bearing 6 a as a fulcrum, so the sample 8 moves in the Y-axis direction. If the tilt cylinder 6 is moved in the Z-axis direction with the knob 10 in the Z-axis direction, the sample holder 7 rotates in the Z-axis direction with the spherical bearing 6a as a fulcrum, so the sample 8 moves in the Z-axis direction. If the holding cylinder 5 is rotated by the driving machine 16 provided in the holding cylinder 5, it rotates around the X axis while holding the inclined cylinder 6.
[0025]
At this time, as shown in FIGS. 2 and 3, since the sample holder 7 rotates around the X axis while maintaining the eccentricity E in the Z-axis direction, the sample 8 is inclined around the X-axis. The sample 8 is mounted on the sample holder 7 so that the X axis, which is the center of inclination, becomes the reference plane of the observation surface, and is controlled so that the observation surface is located at the origin of the X, Y, and Z axes.
[0026]
FIG. 4 is also an XZ sectional view of the side entry sample stage. The holding cylinder 5 is rotatably attached to the mirror body 3, and the spherical bearing 6 a of the inclined cylinder 6 is attached to the holding cylinder 5. The rotation center of the spherical bearing 6 a is decentered in the Z-axis direction with respect to the rotation axis of the holding cylinder 5. The movement mechanism in the X-axis, Y-axis, and Z-axis directions is the same as in FIG. In this example as well as in FIG. 1, the sample can be moved in the X-axis, Y-axis, and Z-axis directions. When the holding cylinder 5 is rotated by the drive unit 16, the eccentric amount E in the Z-axis direction is maintained. Since the inclined cylinder 6 rotates around the X axis, the sample 8 is inclined around the X axis.
[0027]
In this example, the drive means a device whose position can be controlled, such as an actuator or a motor, but if a screw-type knob is used, it can be moved manually.
[0028]
Further, although a knob is used for driving the Z-axis, a driving machine may be used. Further, since the Z-axis direction is between the upper magnetic pole 1a and the lower magnetic pole 1b and the movement amount is very small, the movement mechanism may be omitted.
[0029]
FIG. 5 is a control system diagram of the sample stage of FIGS. An operator inputs a desired use range from the input device 21, and the input value is registered and processed by the processing device 22. The input information processed by the processing device 22 and the position information of the movement range are displayed on the display device 20. The movement range obtained by the processing device 22 is sent to the stage controller 23 and set as the operation limit value of the stage drive unit 24. Within this range, the X axis, Y axis, (Z axis), and tilt positions To control.
[0030]
FIG. 6 shows a movement range deriving process flow. The operator inputs the range (maximum value) of the tilt angle to be used from the input device (process 601). Next, the movement range of the sample 8 is obtained from the input values with respect to the X axis, Y axis, (Z axis), and the tilt angle (process 602). The moving range is a range in which the sample mounting portion 7a and the sample 8 of the sample holder 7 do not interfere with the upper magnetic pole 1a, the lower magnetic pole 1b, and other components. This can be calculated by registering a relational expression obtained from the shape of the sample holder 7 and the specimen 8 in the processing apparatus for a portion where the sample holder 7 interferes with other parts and substituting an input value into the relational expression. . In order to simplify the processing, a plurality of constants may be registered for the input value and referred to. Alternatively, a relational expression and a constant may be registered for the input value and referred to. The obtained moving range is registered in the processing device together with the input value (processing 603). Next, the input value and the movement range are displayed on the display device (process 604). Further, the limit value of the moving range is set in the stage controller (process 605).
[0031]
Note that the processes 603 to 605 are the same even if the order is changed. Further, the height of the sample to be mounted in the process 601 may be input. Further, in the process 601, the tilt angle to be used and the height of the sample may be input. In any case, the movement range can be obtained by registering a calculation formula or a constant.
[0032]
【The invention's effect】
Since the sample holder axis is decentered with respect to the center of the eucentric tilt axis, the tilt center of the sample is higher than the sample holder axis by the amount of eccentricity. The specimen observation (mounting) reference plane is higher than the Eccentric specimen stage without eccentricity, so that it is possible to mount a cross-sectional specimen that is larger (height) than the specimen holder radius and bring the observation plane closer to the bottom surface of the top pole A large inclination angle can be obtained even in the state where the heat is applied.
[0033]
In addition, the sample tilt angle and the sample height to be used can be input, and the stage movement range is limited with respect to the input value, so that an optimum sample movement range can be obtained according to the application.
[Brief description of the drawings]
FIG. 1 is a eucentric sample stage (XZ cross section).
FIG. 2 is a detailed cross-sectional view (YZ cross section) of a sample mounting portion.
FIG. 3 is a detailed cross section of a sample mounting portion (when tilted, YZ cross section).
FIG. 4 is a eucentric sample stage (XZ cross section).
FIG. 5 is a control system diagram of a eucentric sample stage.
FIG. 6 is a movement range derivation processing flow.
FIG. 7 is a eucentric sample stage (XZ cross section).
FIG. 8 is a eucentric sample stage (XY cross section).
FIG. 9 is a detailed cross section (YZ cross section) of the sample mounting portion.
FIG. 10 is a detailed cross section of a sample mounting portion (when tilted, YZ cross section).
FIG. 11 shows a sample manufacturing procedure.
FIG. 12 is a detailed cross-sectional view (YZ cross section) of a sample mounting portion.
FIG. 13 is a detailed cross section of a sample mounting portion (when tilted, YZ cross section).
FIG. 14 is a detailed cross section of a sample mounting portion (YZ cross section).
FIG. 15 is a detailed cross section of the sample mounting portion (when tilted, YZ cross section).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a ... Upper magnetic pole, 1b ... Lower magnetic pole, 2 ... Electron beam, 3 ... Mirror body, 4 ... Support cylinder, 5 ... Holding cylinder, 6 ... Inclined cylinder, 6a ... Spherical bearing, 7 ... Sample holder, 7a ... Sample mounting part 8 ... sample, 8a ... sample observation surface, 9 ... bearing, 10 ... knob, 11, 18 ... pin, 12, 19 ... spring, 13 ... moving body, 14, 15, 16, 17 ... drive, 20 ... display Device: 21 ... Input device, 22 ... Processing device, 23 ... Stage controller, 24 ... Stage drive unit, 25 ... Wafer, 26 ... Wafer cut with width H, 27 ... Wafer cut with length L

Claims (1)

In a charged particle beam apparatus comprising a charged particle beam mirror and a charged particle beam mirror containing an objective lens for converging a charged particle beam generated from the charged particle source,
A sample holder that is inserted from a side of the charged particle beam mirror and supports the sample irradiated to the charged particle beam;
A sample holder support cylinder having an insertion opening for the sample holder to be inserted and having a tilting mechanism for tilting the sample holder with respect to the charged particle beam;
The charged particle beam apparatus according to claim 1, wherein an insertion opening of the sample holder is provided eccentrically in an irradiation direction of the charged particle beam with respect to an inclined center of the sample holder support cylinder.

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