JP2000200577A - Charged particle beam equipment - Google Patents

Abstract

(57) [Summary] A charged particle beam apparatus employing a side entry type sample holder having a tilt function enables to handle a larger sample and obtain a sample image with high resolution. The sample holder has a sample holder inserted from a side of a charged particle beam mirror to support a sample irradiated with a charged particle beam, an insertion opening of the sample holder to be inserted, and the sample holder is connected to a charged particle beam. A sample holder supporting cylinder having a tilting mechanism for tilting the sample holder, the insertion opening of the sample holder is provided eccentrically in the direction of irradiation of the charged particle beam with respect to the center of inclination of the sample holder supporting cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a side entry sample stage for a charged particle beam device, and more particularly to a charged particle beam device having a eucentric sample stage.

[0002]

2. Description of the Related Art A eucentric type side entry sample stage used in a conventional charged particle beam apparatus will be described with reference to FIGS.

A sample stage is provided on a side surface of an objective lens composed of an upper magnetic pole 1a and a 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 such 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 mounted in the holding cylinder 5. The inclined cylinder 6 has a spherical bearing 6a whose fulcrum center is on the X axis, and is rotatably mounted. The inclined cylinder 6 is supported in the Z direction by a knob 10, a pin 11, and a spring 12, which are attached to the holding cylinder 5 and move in the Z direction. The Y direction is supported by a drive unit 17 mounted on the holding cylinder 5 and moved in the Y direction, a pin 18 and a spring 19.

A driving device 16 is mounted on the outside of the holding cylinder 5 and is connected so that the holding cylinder 5 can be rotated. The sample holder 7 is provided with a sample mounting portion 7a at a portion where the optical axis and the holder axis coincide with each other, and the sample 8 is mounted thereon.

[0006] A drive 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 a floating body 13. The floating body 13 has a pivot and a pivot bearing structure at the joint between the sample holder 7 and the drive rod 14, and is rotatable.

Each drive for driving 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 driving device within the range of the movement limit.

In the apparatus having such a configuration, the sample holder 7 is drawn into the mirror body because the inside of the mirror body having the objective lens is in a vacuum, and always pushes the floating body 13 toward the driving device 15. Drive rod 14 is moved to X
By moving it in the axial direction, the sample holder 7
Can be moved in the X-axis direction. Thus, the sample 8 can be moved in the X-axis direction.

When the tilt cylinder 6 is moved in the Y-axis direction by the driving device 17, the sample holder 7 is rotated 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, when 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. When the holding cylinder 5 is further rotated by the driving device 16, the holding cylinder 5 rotates around the X axis while holding the inclined cylinder 6, so that FIG.
The sample 8 can be tilted like 0. By these moving mechanisms, the observation surface of the sample 8 is controlled so as to be always located at the origin of the X axis, the Y axis, and the Z axis.

[0010]

With the advancement of semiconductor technology, the need for an in-lens scanning electron microscope capable of obtaining a sample image with high resolution by narrowing an electron beam has increased. In particular, in an in-lens scanning electron microscope in which a sample is placed between the upper and lower magnetic poles of an objective lens, the size of the sample to be observed is greatly limited, and a sample of several mm square must be made.

The procedure for preparing the sample will be described with reference to FIG. In order to form a sample 27 (length L, width H) from the wafer 25, first, the wafer 27 is cut into a width H and the wafer 2 on a strip is cut.
6 and then cut to length L. However, since this work is performed manually, it is not easy to cut out a few mm square. As shown in FIGS. 9 and 10, in order to perform cross-sectional observation, it was necessary to cut out the width H to only about 3 to 4 mm, which was a very difficult operation. For this reason, an apparatus capable of mounting a larger sample is desired.

On the other hand, a charged particle beam apparatus is required to have a high resolution of a sample image. One method of increasing the resolution is to bring the sample observation surface closer to the lower surface of the upper magnetic pole.

However, in order to solve these problems with the conventional eucentric type side entry sample stage, there is a method of setting only the sample observation surface 8a above the axis of the holder 7 as shown in FIG. Since the center of tilt of the sample is on the X-axis, when the sample is 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, as shown in FIG. 14, there is a method of bringing the sample holder 7 closer to the upper magnetic pole 1a. However, as shown in FIG. 15, the member of the sample mounting portion 7a interferes with the upper magnetic pole 1a. To
The inclination angle Θ becomes small.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and in particular, deals with handling a larger sample in a charged particle beam apparatus employing a side entry type sample holder having a tilting function in which the space for placing the sample is greatly limited. It is an object of the present invention to provide a charged particle beam apparatus which is made possible and suitable for obtaining a sample image with high resolution.

[0015]

In order to solve the above-mentioned problems, the present invention provides a charged particle beam mirror including a charged particle source and an objective lens for converging a charged particle beam generated from the charged particle source. In the charged particle beam device provided with, a sample holder that is inserted from the side of the charged particle beam mirror body and supports the sample irradiated with the charged particle beam, and has an insertion opening of the inserted sample holder. A sample holder supporting cylinder having an inclination mechanism for inclining the sample holder with respect to the charged particle beam, wherein an insertion opening of the sample holder is directed to the irradiation center of the charged particle beam with respect to a center of inclination of the sample holder supporting cylinder. And a charged particle beam device provided eccentrically to the charged particle beam device.

By providing such a charged particle beam apparatus,
Observation of a large sample piece can be performed while maintaining a large tilt angle, and a sample image with higher resolution can be obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A sample holder inserted into a sample stage slides in the X-axis direction, makes a rotational movement in the Y-axis and Z-axis directions with a spherical bearing as a fulcrum, and further rotates the holding cylinder. It rotates in a state of being eccentric in the Z-axis direction from the axis. Therefore, the sample moves in the X-axis, Y-axis, and Z-axis directions, and tilts around the X-axis.

Further, the X-axis, Y-axis, (Z-axis),
The range of movement of the tilt angle is found and the range of movement of the sample is limited.

An embodiment of the present invention will be described below with reference to FIGS. Items having the same numbers as those in FIGS. 7 to 15 indicate the same components.

FIG. 1 shows the X of the side entry sample stage.
It is -Z sectional drawing. 2 and 3 are detailed cross-sectional views of the sample mounting section. Insert the sample holder insertion hole into the holding cylinder 5
An inclined cylinder 6 eccentric in the axial direction is arranged. 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 attached to the mirror body 3. Sample 8
Is inserted into the inclined cylinder 6 and connected to the floating body 13.

The sample holder provided in the sample holder 7 is formed in a concave shape along the optical axis as shown in the figure. It is preferable that the width of the concave portion is larger than the thickness of the semiconductor wafer, for example. This is because the sample piece cut out for the cross-sectional observation described above is inserted and observed.

In the embodiment of the present invention, the distance between the bottom of the recess and the rotation axis of the holding cylinder 5 can be increased. That is, since the sample piece can be cut out larger than in the conventional technique, fine preparation is not required, and the preparation of the observation sample becomes easy.

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 effectively used for arranging the sample pieces.

Here, the driving rod 1 is driven by the driving device 15 in the X-axis direction.
When the sample holder 4 is moved, the sample holder 7 slides in the X-axis direction, so that the sample 8 moves in the X-axis direction. When the inclined cylinder 6 is moved in the Y-axis direction by the Y-axis direction driving device 17, the sample holder 7 rotates in the Y-axis direction with the spherical bearing 6a as a fulcrum, so that the sample 8 moves in the Y-axis direction. Z axis direction knob 1
If the tilt cylinder 6 is moved in the Z-axis direction at 0, the sample holder 7 rotates in the Z-axis direction with the spherical bearing 6a as a fulcrum, so that the sample 8 moves in the Z-axis direction. When the holding cylinder 5 is rotated by the driving device 16 provided on the holding cylinder 5, it rotates around the X axis while holding the inclined cylinder 6.

At this time, as shown in FIGS. 2 and 3, the sample holder 7 rotates around the X axis while maintaining the eccentricity E in the Z axis direction, so that the sample 8 tilts around the X axis. . The sample 8 is mounted on the sample holder 7 so that the X axis, which is the tilt center, becomes the reference plane of the observation plane, and is controlled so that the observation plane is located at the origin of the X, Y, and Z axes.

FIG. 4 also shows the X of the side entry sample stage.
It is -Z sectional drawing. 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 6a is eccentric in the Z-axis direction with respect to the rotation axis of the holding cylinder 5. The moving mechanism in the X-axis, Y-axis, and Z-axis directions is the same as in FIG. In this example, 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 driving device 16, the eccentricity E in the Z-axis direction is maintained. Since the inclined cylinder 6 rotates around the X axis, the sample 8
Tilts around the X axis.

In this embodiment, the drive means a device whose position can be controlled, such as an actuator or a motor. If a screw-type knob is used, it can be moved manually.

Although the knob is used for driving the Z axis, a driving device may be used. Further, since the Z-axis direction is located between the upper magnetic pole 1a and the lower magnetic pole 1b and has a small amount of movement, the moving mechanism may be omitted in some cases.

FIG. 5 is a control system diagram of the sample stage shown in FIGS. The input device 21 allows the operator to specify a desired use range.
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 moving range are displayed on the display device 20. Further, the movement range obtained by the processing device 22 corresponds to the stage controller 23.
Is set as an operation limit value of the stage driving device 24, and the positions of the X axis, the Y axis, the (Z axis), and the inclination are controlled within this range.

FIG. 6 shows a moving 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, from the input value, X
The moving range of the sample 8 is determined for the axis, Y axis, (Z axis), and tilt angle (process 602). The moving range is the sample holder 7
The sample mounting portion 7a and the sample 8 are in a range where they 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 shapes of the sample holder 7 and the sample 8 in the processing device for a portion where the sample holder 7 interferes with another part, 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 this may be referred to. Alternatively, a relational expression and a constant may be registered for an input value, and this may be referred to. The obtained moving range is registered in the processing device together with the input value (process 603). Next, the input value and the movement range are displayed on the display device (process 604). Further, it is set as a limit value of the movement range in the stage controller (process 605).

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 inclination angle and the sample height to be used may be input. In any case, the moving range can be obtained by registering the calculation formula and the constant.

[0032]

Since the sample holder axis is eccentric 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 observation (mounting) reference surface of the sample is higher than the eccentric sample stage without eccentricity, so that a cross-section sample (having a height) larger than the sample holder radius can be mounted, and the observation surface is brought closer to the lower surface of the upper magnetic pole. A large inclination angle can be obtained even in the inclined state.

Further, a sample tilt angle and a sample height to be used can be input, and the movement range of the stage is limited with respect to the input values, so that an optimum sample movement range can be obtained according to the application.

[Brief description of the drawings]

FIG. 1 shows a eucentric sample stage (XZ section).

FIG. 2 is a detailed cross section (YZ cross section) of the sample mounting portion.

FIG. 3 is a detailed cross section of the sample mounting portion (when inclined, YZ cross section).

FIG. 4 shows a eucentric sample stage (XZ section).

FIG. 5 is a control system diagram of a eucentric sample stage.

FIG. 6 is a moving range derivation processing flow.

FIG. 7 shows a eucentric sample stage (XZ section).

FIG. 8 shows 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 the sample mounting portion (when inclined, YZ cross section).

FIG. 11 shows a sample manufacturing procedure.

FIG. 12 is a detailed cross section (YZ cross section) of the sample mounting portion.

FIG. 13 is a detailed cross section of the sample mounting portion (when inclined, YZ cross section).

FIG. 14 is a detailed cross section (YZ cross section) of the sample mounting section.

FIG. 15 is a detailed cross section of the sample mounting portion (when inclined, YZ cross section).

[Explanation of symbols]

1a: upper magnetic pole, 1b: lower magnetic pole, 2: electron beam, 3: mirror,
4 support cylinder, 5 holding cylinder, 6 inclined cylinder, 6a spherical bearing, 7 sample holder, 7a sample mounting portion, 8 sample
8a: sample observation surface, 9: bearing, 10: knob, 1
1, 18 ... pin, 12, 19 ... spring, 13 ... floating body, 1
4, 15, 16, 17: driving machine, 20: display device, 21
... Input device, 22 ... Processing device, 23 ... Stage controller, 24 ... Stage driving machine, 25 ... Wafer, 26
... wafer cut out in width H, 27 ... wafer cut out in length L.

Claims (7)

[Claims] 1. A charged particle beam apparatus comprising: a charged particle beam source having a charged particle beam source and an objective lens for converging a charged particle beam generated from the charged particle beam source; A sample holder inserted from a side of the sample holder for supporting a sample irradiated with the charged particle beam, and an insertion opening of the sample holder to be inserted,
A sample holder supporting cylinder having an inclination mechanism for inclining the sample holder with respect to the charged particle beam, wherein an insertion opening of the sample holder is arranged in the irradiation direction of the charged particle beam with respect to a tilt center of the sample holder supporting cylinder. A charged particle beam device provided eccentrically. 2. A charged particle beam apparatus according to claim 1, wherein said sample holder is disposed between an upper magnetic pole and a lower magnetic pole of said objective lens. 3. The charged particle beam apparatus according to claim 1, wherein the sample holder has a concave portion for holding the sample. 4. The charged particle beam apparatus according to claim 3, wherein the recess is formed so that a sample having the same thickness as the semiconductor wafer can be inserted. 5. The charged particle beam mirror or the sample holder support cylinder according to claim 1, wherein the charged particle beam mirror or the sample holder support cylinder is arranged such that the sample holder is positioned relative to the charged particle beam mirror in the optical axis direction of the charged particle beam and the charged particle beam. Any of the vertical directions of the line,
Or a charged particle beam device comprising a moving mechanism for moving to both. 6. The apparatus according to claim 5, further comprising: means for setting an inclination angle of the tilt mechanism, and means for determining a moving range of the moving mechanism based on the tilt angle set by the setting means. Charged particle beam device. 7. A means for setting the height of a sample to be mounted on the sample holder or the height of a sample protruding from a concave portion of the sample holder according to claim 5 or 6, wherein the height is set by the setting means. A charged particle beam apparatus comprising: means for determining a moving range of the moving mechanism based on a height.