JPH11213932A - Sample device in charged-particle beam device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a sample device in a charged-particle beam device, capable of positioning a sample moving two-dimensionally on an inclining mechanism by the use of a laser length-measuring machine. SOLUTION: A moving mirror 23 is fixed on a sample table 1, and interferometers 22, 26 for causing measured light to interfere with referential light are disposed integrally with an inclining frame 15 inclining the moving table 1. An optical axis of laser is not displaced by inclination of the sample table 1, a moving distance of the sample table 1 can be accurately measured by using a laser length-measuring machine, and positioning of a sample can be accurately performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample device suitable for use in a scanning electron microscope, an electron beam length measuring device, and the like.

[0002]

2. Description of the Related Art In a scanning electron microscope, an electron beam generated and accelerated from an electron gun is finely focused by a condenser lens and an objective lens and is irradiated on a sample. Then, an arbitrary two-dimensional area of the sample is scanned with an electron beam, secondary electrons and reflected electrons generated from the sample are detected, and a detection signal is supplied to a cathode ray tube synchronized with the scanning of the electron beam to scan the sample. I'm trying to get

In such a scanning electron microscope, when observing a sample, the sample is moved, rotated, or tilted in the X and Y directions. Therefore, the sample is placed on a sample stage provided with a moving mechanism in the X and Y directions, a rotating mechanism, and a tilting mechanism.

FIG. 1 is a plan view of a sample apparatus, and 1 is a sample table on which a sample is placed. The sample stage 1 is a Y-direction rail 2
Is arranged so that it can move in the Y direction.
The direction rail 2 is arranged on the X direction rail 3 so as to be movable in the X direction.

[0005] A feed screw 4 is provided on the Y-direction rail 2, and the feed screw 4 is rotated by a motor 6 arranged outside the sample chamber wall 5. The rotation of the motor 6 is transmitted to the feed screw 4 by a drive shaft 7 including a universal joint.

The feed screw 4 is engaged with a nut (not shown) fixed to the bottom of the sample table 1.
By rotating the sample stage 1, the sample stage 1 fixed to the nut
Moves in the Y direction.

A feed screw 8 is provided on the X-direction rail 3, and the feed screw 8 is rotated by a motor 9 disposed outside the sample chamber wall 5. The rotation of the motor 9 is controlled by a drive shaft 10 including a universal joint.
Conveyed to.

The feed screw 8 is engaged with a nut (not shown) fixed to the bottom of the Y-direction rail 2, and by rotating the feed screw 8, the feed screw 8 is fixed to the nut.
The direction rail 2 moves in the X direction.

[0009] Encoders 11 and 12 are attached to the feed screw 4 in the Y direction and the feed screw 8 in the X direction, respectively, and a signal corresponding to the rotation speed of each feed screw is obtained. Based on the signals from the encoders 11 and 12, the moving distances of the sample table 1 in the X and Y directions are obtained.
The positioning of the sample stage 1 is performed according to this distance.

Although not shown, the X-direction rail 3
Is mounted on an inclined frame for inclining the sample table 1, and a hollow inclined shaft for inclining the inclined frame is provided on the sample chamber wall 5. The drive shaft 7 and the drive shaft 10 are provided so as to penetrate through the hollow inclined shaft.

[0011]

When the positioning of the sample stage 1 is performed by the outputs of the encoders 11 and 12 in the above configuration, the lead errors (pitch unevenness) of the feed screws 4 and 8, the X and Y direction rails 3 and 5 to 10 due to distortion of 2, etc.
A positioning error of μm occurs. These cannot be improved even if the precision of each component is strictly manufactured.

For precise positioning of the sample table 1, a laser length measuring device is widely used. However, FIG.
When the necessary components of the laser length measuring device are arranged on the inclined frame in the above configuration, it is necessary to take out the interference light to the outside of the sample chamber wall along the center of the inclined frame. Since the shafts 7 and 10 are arranged, interference light cannot be actually extracted to the outside. Therefore, it is difficult to position the sample on the stage provided with the tilting mechanism using the laser length measuring device.

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and an object of the present invention is to provide a sample apparatus having a tilting mechanism, in which a sample can be aligned using a laser length measuring device. To be realized.

[0014]

A sample apparatus in a charged particle beam apparatus according to the first invention irradiates a charged particle beam onto a sample by narrowing the charged particle beam, and two-dimensionally scans the charged particle beam on the sample. Then, a signal obtained by irradiating the sample with the charged particle beam is detected, a scan image of the sample is displayed based on the detection signal, the sample is placed on the tilt mechanism, and the sample is tilted by the tilt mechanism. In the charged particle beam apparatus configured as above, the sample stage on which the sample is placed is arranged on the inclined frame, and the sample stage is moved in the X direction and the Y direction on the inclined frame.
And a movable mirror in the X and Y directions is arranged on the sample stage, and an X-direction interferometer and a Y-direction interferometer that move integrally with the inclined frame are provided. It is characterized in that the measuring light from the interferometer is applied to the X-direction moving mirror, and the measuring light from the Y-direction interferometer is applied to the Y-direction moving mirror.

In the first invention, a movable mirror constituting a laser length measuring device is provided on a sample stage, and interferometers in the X and Y directions are arranged on an inclined frame for tilting the sample stage. The positional relationship between the interferometer and the moving mirror was not changed.

According to a second aspect of the present invention, in the first aspect, an inclination axis for inclining the inclined frame is disposed so as to penetrate a wall portion of the sample chamber in which the sample stage is arranged, and an inclination portion of an outer portion of the sample chamber is inclined. A laser light source that constitutes a laser interferometer, a detector that detects interference light from the X-direction interferometer, and a detector that detects interference light from the Y-direction interferometer are arranged on the axis, and light from the laser light source passes through the hollow inclined axis. It was configured to pass light from the interferometer.

In the second invention, the laser light source, the interferometer, the moving mirror, and the detector constituting the laser length measuring device are constituted so as to be integrally inclined with the inclined frame. The position relation of was not changed.

According to a third aspect of the present invention, in the first aspect, an inclination axis for inclining the inclined frame is arranged so as to penetrate a wall portion of the sample chamber where the sample stage is arranged, and a laser is provided on an outer portion of the sample chamber. A laser light source, an X-direction interferometer, and a detector that detects interference light from the Y-direction interferometer are arranged, and light from the interferometer is guided to the detector through a hollow inclined axis. It was configured to pass an optical fiber.

In the third aspect of the present invention, the interferometer and the detector are connected by an optical fiber so that the position of the detector can be freely set. According to a fourth aspect of the present invention, in any one of the first to third aspects, an inclination axis for inclining the inclination frame is provided at both ends of the inclination frame, and each inclination axis is supported by a wall portion of the sample chamber. did.

According to a fifth aspect of the present invention, in any one of the first to third aspects, a tilt axis for tilting the tilt frame is provided at one end of the tilt frame, and the tilt axis is supported by a wall portion of the sample chamber. It was configured to be.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a plan view of the sample device according to the present invention, and FIG. 3 is a side view thereof.
The same or similar components as those of the conventional device shown in FIG. In the figure, reference numeral 1 denotes a sample stage on which a sample is placed. The sample table 1 is disposed on the Y-direction rail 2 so as to be movable in the Y-direction.
Are arranged on the X-direction rail 3 on the inclined frame 15 so as to be movable in the X-direction.

A Y-direction feed screw 4 is provided on the Y-direction rail 2, and the feed screw 4 is rotated by a motor arranged outside the sample chamber wall 5. In FIG. 2, the drive shaft including the Y-direction feed screw, the motor, and the universal joint for transmitting the rotation of the motor is not shown.

The Y-direction feed screw 4 is meshed with a nut (not shown) fixed to the bottom of the sample table 1. By rotating the Y-direction feed screw 4, the sample table 1 fixed to the nut is moved. Move in the Y direction.

A feed screw 8 is provided on the inclined frame 15 provided with the X-direction rail 3, and the feed screw 8 is rotated by a motor 9 arranged outside the sample chamber wall 5. The rotation of the motor 9 is transmitted to the feed screw 8 by a drive shaft 10 including a universal joint.

The feed screw 8 is engaged with a nut 16 fixed to the bottom of the Y-direction rail 2, and by rotating the feed screw 8, the Y-direction rail 2 and the sample table 1 fixed to the nut 16 become X-shaped. Move in the direction.

The tilting frame 15 is connected to a tilting shaft 17. By rotating the tilting shaft 17, the tilting frame 15 can be tilted about the surface of a sample 18 placed on the sample table 1 as an axis. .

The inclined shaft 17 is a hollow shaft, and the laser light source 1 which rotates integrally with the inclined shaft 17 is provided inside the hollow shaft.
9 passes through the laser beam L1. Note that the axis of the laser beam L1 from the laser light source 19 coincides with the tilt center axis of the tilt frame 15.

The light L1 from the laser light source 19 passes through the glass window 20, enters the sample chamber, and is fixed to the inclined frame 15 and is disposed on a table 15a that moves integrally with the inclined frame 15. Is split into two lights. One of the split lights L2 (transmitted light) is
The light is incident on the X-direction interferometer 22 arranged on 5a. The light transmitted through the interferometer 22 is transferred to the L-shaped movable mirror 23 on the sample stage 1.
And is reflected.

In the interferometer 22, the light L2 incident from the beam splitter 21 is split, one transmitted light is irradiated to the movable mirror 23, the other reflected light is used as reference light, and each light is used as an interference light. Let me. The interfered light passes through the beam splitter 21 and is incident on a detector 24 disposed outside the sample chamber wall 5 and detected.

The other light L3 generated from the laser light source 19 and reflected by the beam splitter 21 is transmitted to the table 15a.
It is reflected by the reflecting mirror 25 fixed on the
The light enters the upper Y-direction interferometer 26. The light reflected by the interferometer 26 enters the L-shaped movable mirror 23 on the sample stage 1 and is reflected.

In the interferometer 26, the light L3 incident from the beam splitter 21 is split, one reflected light is irradiated to the movable mirror 23, and the other transmitted light is used as reference light.
Each light interferes. The interfering light is reflected by the reflecting mirror 25, reflected by the beam splitter 21, incident on a detector 27 arranged outside the sample chamber wall 5, and detected.

FIG. 4 shows the laser light L1 from the laser light source 19 described above, the two types of light L2 and L3 split by the beam splitter 21, the X-direction interferometer 22, and the moving mirror 23.

In the above configuration, the sample 18 is moved in the X direction by rotating the motor 9 and rotating the feed screw 8 to drive the nut meshed with the feed screw 8,
This is performed by moving the rail 2 in the X direction.
To move in the Y direction, the feed screw 4 is rotated to rotate the sample stage 1
Is moved in the Y direction. Further, the sample 18 is tilted by rotating the tilt shaft 17 and tilting the tilt frame 15 to tilt each component placed on the tilt frame 15.

Here, the feed screw 8 is rotated, and the sample 18 is rotated.
When the (sample stage 1) is moved in the X direction, the length of the measurement light (light reflected by the moving mirror 23) in the X-direction interferometer 22 changes, and the length of the interference light with the reference light in the interferometer 22 changes. The intensity changes. The interference light in the interferometer 22 is
Detected by detector 24. The detection signal is supplied to a length measuring unit (not shown), and the moving distance of the sample table 1 in the X direction is measured.

Next, the feed screw 4 is rotated, and the sample 18 is rotated.
When the (sample stage 1) is moved in the Y direction, the length of the measurement light (light reflected by the moving mirror 23) in the Y-direction interferometer 26 changes, and the interference light with the reference light in the interferometer 26 changes. The intensity changes. The interference light in the interferometer 26 is
Detected by detector 27. The detection signal is supplied to a length measuring unit (not shown), and the moving distance of the sample table 1 in the Y direction is measured.

As described above, in the above configuration, the sample stage 1
, A movable mirror 23 is fixed to the moving table 1, and further, interferometers 22 and 2 for causing the measuring light and the reference light to interfere with the inclined frame 15 for tilting the moving table 1.
6 are disposed integrally, so that the laser optical axis does not shift even when the sample table 1 is tilted. Therefore, it is possible to accurately measure the moving distance of the sample table 1 using the laser length measuring device, and it is possible to accurately position the sample.

FIG. 5 shows another embodiment of the present invention. In FIG. 5, light interfered by the X-direction interferometer 22 is supplied to the detector 24 via the optical fiber 30, and light interfered by the Y-direction interferometer 26 is supplied to the detector 27 via the optical fiber 31. Is done. In FIG. 5, a laser light source and each interferometer 2
The optical paths of the light supplied to the light sources 2 and 26 are omitted.

In the configuration shown in FIG. 5, the detectors 24 and 27, the laser light source, and the like disposed on the atmosphere side of the inclined frame 15 do not need to be mounted on a table that rotates integrally with the inclined frame.
They can be placed at any position around the sample chamber. Of course, even if they are placed on a table that rotates integrally with the inclined frame, their arrangement can be made freely.

FIG. 6 shows still another embodiment of the present invention. In this embodiment, both ends of the inclined frame 15 are connected to the sample chamber wall 5.
Instead of the two-sided configuration of FIGS. 2 and 3 supported by
5 has a cantilever configuration in which only one end is supported.

Although the embodiment of the present invention has been described in detail, the present invention is not limited to this embodiment. For example, the present invention can be applied not only to an electron beam device such as a scanning electron microscope, but also to a scanning ion beam device configured to scan a finely focused ion beam on a sample. Further, the case where the sample table is moved two-dimensionally and further tilted has been described, but a configuration may be adopted in which a rotation mechanism of the sample table is provided on an inclined frame.

[0041]

As described above, in the first invention,
A sample stage on which a sample is placed is arranged on an inclined frame, and the sample stage is configured to be movable in the X direction and the Y direction on the inclined frame, and a moving mirror in the X direction and the Y direction is arranged on the sample stage. ,
An X-direction interferometer and a Y-direction interferometer that move integrally with the inclined frame are arranged, and the measuring light from the X-direction interferometer is irradiated on the X-direction moving mirror, and the measuring light from the Y-direction interferometer is measured. Is irradiated on the Y-direction movable mirror. As a result, the positional relationship between the interferometer and the moving mirror does not change even when the sample table is tilted. Therefore, even with a sample device using a tilt mechanism, two-dimensional positioning of the sample can be accurately performed using a laser length measuring device. Can be done.

According to a second aspect of the present invention, in the first aspect, an inclination axis for inclining the inclined frame is disposed so as to penetrate a wall portion of the sample chamber in which the sample stage is arranged, and an inclination portion of an outer portion of the sample chamber is inclined. A laser light source that constitutes a laser interferometer, a detector that detects interference light from the X-direction interferometer, and a detector that detects interference light from the Y-direction interferometer are arranged on the axis, and light from the laser light source passes through the hollow inclined axis. It was configured to pass light from the interferometer. As a result, the laser light source, interferometer,
Since the moving mirror and the detector are tilted integrally with the tilt frame, the positional relationship of each component does not change even with the tilt of the sample table,
The two-dimensional positioning of the sample can be accurately performed by the laser length measuring device.

According to a third aspect, in the first aspect, a tilt axis for tilting the tilt frame is disposed so as to penetrate a wall portion of the sample chamber in which the sample stage is disposed, and a laser is provided on an outer portion of the sample chamber. A laser light source, an X-direction interferometer, and a detector that detects interference light from the Y-direction interferometer are arranged, and light from the interferometer is guided to the detector through a hollow inclined axis. It was configured to pass an optical fiber. As a result,
Since the interferometer and the detector are connected by a flexible optical fiber, the degree of freedom of the installation position of the detector can be increased.

According to a fourth aspect of the present invention, in any one of the first to third aspects, an inclined axis for inclining the inclined frame is provided at both ends of the inclined frame, and each inclined axis is supported by a wall portion of the sample chamber. With such a configuration, the same effects as those of the first invention are obtained.

According to a fifth aspect of the present invention, in any one of the first to third aspects, a tilt axis for tilting the tilt frame is provided at one end of the tilt frame, and the tilt axis is supported by a wall portion of the sample chamber. Therefore, the present invention has the same effect as the first invention.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional sample device such as a scanning electron microscope.

FIG. 2 is a plan view of a sample device according to the present invention.

FIG. 3 is a side view of the sample device of FIG. 2;

FIG. 4 is a diagram illustrating a beam splitter, an interferometer, and a movable mirror in the configuration of FIG. 2;

FIG. 5 is a diagram showing another embodiment of the present invention.

FIG. 6 is a diagram showing still another embodiment according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 sample table 2 Y rail 3 X rail 4,8 feed screw 5 sample chamber wall 6,9 motor 7,10 drive shaft 15 inclined frame 17 inclined axis 18 sample 19 laser light source 20 glass window 21 beam splitter 22,26 interferometer 23 Moving mirror 24, 27 Detector

Claims (5)

[Claims] 1. A method for irradiating a charged particle beam on a sample by narrowing down the charged particle beam, scanning the charged particle beam two-dimensionally on the sample, and detecting a signal obtained by irradiating the charged particle beam on the sample. In a charged particle beam apparatus that displays a scan image of the sample based on the detection signal, mounts the sample on the tilting mechanism, and tilts the sample by the tilting mechanism, the sample stage on which the sample is mounted is positioned on the tilt frame. On the inclined frame, the sample stage can be moved in the X direction and the Y direction, and a movable mirror in the X direction and the Y direction is arranged on the sample stage to move integrally with the inclined frame. A direction interferometer and a Y direction interferometer are provided, and the measuring light from the X direction interferometer is irradiated on the X direction moving mirror, and the measuring light from the Y direction interferometer is irradiated on the Y direction moving mirror. Sample device in the configured charged particle beam device . 2. A laser, wherein a tilt axis for tilting the tilt frame is arranged to penetrate a wall portion of the sample chamber in which the sample stage is arranged, and a laser interferometer is formed on the tilt axis of an outer portion of the sample chamber. A light source, a detector that detects interference light from the X-direction interferometer, and a detector that detects interference light from the Y-direction interferometer are arranged so that light from the laser light source and light from the interferometer pass through the hollow inclined axis. A sample device in the charged particle beam device according to claim 1. 3. A laser light source which constitutes a laser interferometer on an outer portion of the sample chamber, wherein a tilt axis for tilting the tilt frame is penetrated through a wall portion of the sample chamber in which the sample stage is disposed, and an X direction. 2. An interferometer and a detector for detecting interference light from the Y-direction interferometer are arranged, and an optical fiber for guiding light from the interferometer to the detector is passed through a hollow inclined axis. A sample device in the charged particle beam device according to the above. 4. The charged particle beam apparatus according to claim 1, wherein tilt axes for tilting the tilt frame are provided at both ends of the tilt frame, and each tilt axis is supported by a wall portion of the sample chamber. Sample device in. 5. The charged particle according to claim 1, wherein a tilt axis for tilting the tilt frame is provided at one end of the tilt frame, and the tilt axis is supported by a wall portion of the sample chamber. Sample equipment in beam equipment.