JPH1055950A - Specimen supporting mechanism in electronic beam aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a specimen to be supported adding no excessive load to the same while making alignment of the specimen within an electronic beam aligner. SOLUTION: A specimen 12 is inserted into a specimen container 11 provided on a frame 10. In the frame 10, abutted parts 13a-13c are provided on the three positions of the specimen container 11 for making alignment of the specimen 12 in the horizontal direction. Furthermore, three each of clamp mechanisms 14a-14c are provided on the frame 10 wherein the specimen 12 inserted into the specimen container 11 is held from front and back, thereby specimen 12 to be fixed and held as well as the alignment thereof in the vertical direction to be made.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a sample support mechanism for fixing and holding a sample to be exposed by an electron beam exposure apparatus.

[0002]

2. Description of the Related Art In many cases, when a sample is exposed by using an electron beam exposure apparatus, the sample is held in a cassette as shown in FIG. 8 and the cassette is set on a stage in the apparatus in many cases.

A conventional sample support mechanism will be described with reference to FIG. The sample 51 is transported into the cassette body, and is pressed against the butting 52 in two directions to be aligned. Thereafter, the frame 5 is pushed up by the four lower clamp pins 53 while being pressed in the horizontal direction.
4 are clamped and fixed by the four upper clamp claws 55 and the lower clamp pins 53 fixed to the four. 4 above
The positions of the upper clamp claws 55 in the height direction of the clamp surface are assembled with an accuracy of several μm. The lower clamp pin 53 is pushed up by pushing up the attached clamp bar 56 with a coil spring 57. The abutment 52 is vertically attached to the frame 54. Further, the clamp bar 56 is supported by a leaf spring 58. The ground mechanism 59 comes into contact with the held drawing surface of the sample 51, and the electric charge accumulated during electron beam drawing is transferred to the ground mechanism 5.
It escapes to the outside through 9.

Most of the samples in the electron beam exposure apparatus are thin plates such as a photomask. It is known that when such a sample is bent, its surface expands and contracts, and the position of a drawn pattern shifts.

[0005] In the above-mentioned conventional device, the sample is clamped on the basis of the upper surface, so that the height of the drawing surface always falls within a certain range without the Z stage. Therefore, there is an advantage that the focal length can be kept within the focal depth of the electron optical system.

[0006] However, on the other hand, the following variations in deflection between samples occur, and as a result, there is a disadvantage that the pattern position accuracy between samples varies. (1) Since the support is provided at four points, the support is in an indeterminate state, and the sample is forcibly bent and the sample is bent. Usually, each sample has a different unique shape, so that a deflection occurs between the samples due to the support mechanism. (2) Since the sample contact surface of each upper clamp claw and the sample contact surface of the lower clamp pin are both flat, there are many constraints and a moment load is applied to the sample.
Since the magnitude of the moment changes depending on the specific shape of the sample, the deflection varies between the samples. (3) The horizontal restricting force of the leaf spring, which is the support mechanism of the clamp bar, is small, the centers of the lower clamp pins are uneven, and the moment load applied between the samples is different. Occurs. (4) Since the pressing point of the ground mechanism is far from the supporting point of the sample, a load is applied to the sample, and the surface shape changes. Since this load changes depending on the specific shape of the sample,
Deflection fluctuation occurs between samples. (5) Since the drawing pattern is formed based on the outer shape of the sample, the sample is clamped in a state where the sample is pressed against the butting from two directions and aligned. Therefore, the edge of the sample is pulled by friction, and the surface shape changes. This deformation is
Since the pressure varies depending on the pressing force and the shape of the end face of the sample, the deflection varies between the samples.

As described above, conventionally, since a large load is applied to a sample, the deflection between the samples varies, and as a result, there is a drawback that it is difficult to improve the positional accuracy of the drawing pattern. I was

[0008]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to support a sample while positioning the sample without applying an excessive load to the sample. Accordingly, it is an object of the present invention to provide a sample support mechanism in an electron beam exposure apparatus which solves the drawbacks of the conventional method.

[0009]

The sample support mechanism in the electron beam exposure apparatus according to the present invention has three clamp mechanisms for clamping the sample at different points of the sample from both front and back sides. Each of the mechanisms
A first clamp portion having a flat contact surface with the sample and a second clamp portion disposed coaxially and opposed to the first clamp portion and having a convex contact surface with the sample. Wherein one of the first and second clamps is movable in the normal direction of the sample.

[0010] The plane size of the contact surface with the sample in the first clamp portion is set in the direction of the sample surface of one of the first and second clamp portions which can be moved in the normal direction of the sample. It is characterized in that the positional accuracy is not less than the variation.

A mechanism in which one or more of the first and second clamp portions movable in the normal direction of the sample are arranged such that two or more U-shaped leaf springs are out of phase with each other. Has a degree of freedom in the sample normal direction and is constrained in the sample surface direction.

One of the first and second clamps movable in the normal direction of the sample has a degree of freedom in the normal direction of the sample by a mechanism composed of a rod and a bearing. It is characterized by being constrained in the sample surface direction.

The sample support mechanism in the electron beam exposure apparatus according to the present invention has three clamp mechanisms for clamping the sample by sandwiching the sample from both front and back surfaces at different points of the sample, and includes an earth mechanism that comes into contact with the drawing surface of the sample. And a contact point between the ground mechanism and the drawing surface of the sample is provided so as to be in the vicinity of one of the three clamp mechanisms.

The ratio of the clamping force for sandwiching the sample in each of the three clamp mechanisms is added to the first or second clamp section below the sample support mechanism when the sample support mechanism is installed horizontally and the sample is supported. The ratio of the weight of the sample to its own weight is made substantially equal.

The support points of the three clamp mechanisms are arranged such that the center of gravity of the triangle formed by the respective support points of the three clamp mechanisms substantially coincides with the center of gravity of the sample.

As a method for aligning the sample and the support mechanism when supporting the sample in the electron beam exposure apparatus, a member having two or three tapered curved surfaces is set on the substrate portion of the support mechanism, Is desirably pressed against the above member to perform positioning.

As a method of aligning the sample and the support mechanism when supporting the sample in the electron beam exposure apparatus, a member having two or three convex curved surfaces is set on a substrate portion of the support mechanism via a piezoelectric element. Then, it is desirable that the sample is pressed against the convex curved surface of the above member to perform the alignment. Further, in the above-described alignment method, it is desirable to release a load pressing the sample immediately before clamping.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described by way of embodiments with reference to the drawings. FIG. 1 is a top view showing an overall configuration of a sample support mechanism in an electron beam exposure apparatus according to a first embodiment of the present invention. The frame 10 is provided with, for example, a square-shaped sample storage unit 11 adapted to the planar shape of the sample, and the sample 12 is inserted into the sample storage unit 11 from the direction of the arrow in the figure. Also, frame 1
In FIG. 0, abutments 13 a to 13 c are provided at a total of three places of two sides adjacent to each other among the four sides of the rectangular shape of the sample storage section 11, and the sample 12 inserted into the sample storage section 11 is provided.
The two sides including the front end surface of the sample abut against these abutments 13a to 13c, whereby the sample 12 is aligned in the horizontal direction.

The frame 10 is provided with three clamp mechanisms 14a to 14c. In these three clamp mechanisms 14a to 14c, the sample 12 inserted into the sample storage unit 11 is sandwiched from the front and back surfaces, whereby the sample 12 is fixed and held, and also the vertical position is adjusted.

Further, three clamp mechanisms 14a to 14c
Of the sample 1 is in the immediate vicinity of one clamp mechanism 14b.
An earthing mechanism 15 is provided which is in contact with a drawing surface (not shown) of No. 2 and charges accumulated in the sample 12 at the time of writing are released to the outside via this earthing mechanism 15.

FIG. 2 is a partial sectional view showing a schematic configuration of the one clamp mechanism 14b. The remaining two clamp mechanisms 14a and 14c have the same configuration, and a description thereof will be omitted.

The above-mentioned clamping mechanism comprises a pair of upper and lower clamp portions 21 and 22 which are opposed to each other. The upper clamp portion 21 is fixed to the frame 10 and has a contact surface 23 at the tip of the upper clamp portion 21 for contacting the sample 12. The contact surface 23 is flat.

The lower clamp portion 22 has a contact 24 whose surface in contact with the sample 12 has a convex curved shape and whose contact point with the sample is in point contact (or in a small area). The lower clamp portion 22 has a degree of freedom in the vertical direction, and clamp / unclamp is performed by moving the contact 24 up and down. Also, the clamping force is
5 generated. Although the lower clamp portion 22 is constrained in the horizontal direction, there is always a variation in the reproducibility of the position of the contact 24 when clamped. Assuming that this variation is δ, the area of the contact surface 23 of the upper clamp 21 is made larger than δ.

According to such a configuration, the contact surface 23 of the upper clamp portion 21 which is a surface load always exists on the vertical line of the support point of the lower clamp portion 22 which is a point load. No moment is generated. As a result, unnecessary deflection fluctuation is not given to the sample, and the drawing accuracy is not deteriorated when the sample is used as a sample support mechanism of the electron beam exposure apparatus. In the example of FIG. 2, the contact surface 23 of the upper clamp portion 21 has been described as a flat surface, and the surface of the contactor 24 of the lower clamp portion 22 has been described as a convex curved surface.

Further, according to the above configuration, the grounding mechanism 15
Are disposed very close to one clamp mechanism 14b. The load on the sample by the grounding mechanism 15 is considerably smaller than the clamping force, but is not negligible. However, if the grounding mechanism 15 is arranged very close to the clamp mechanism, the moment applied to the clamp mechanism can be minimized even with the same load. As a result,
The deflection fluctuation added to the sample is minimized, and the drawing accuracy is not deteriorated.

However, even with the above structure, if the reproducibility of the position of the lower clamp is poor, it is necessary to increase the area of the contact surface in the upper clamp. As a result, in the state where the contact surface of the upper clamp and the sample surface are not parallel,
Instead of the above-mentioned load surface, it is supported at the end point of the upper clamp portion, and a point load results. In such a support, a moment is naturally generated in the clamp mechanism, and the deflection of the sample is varied. Therefore, the position reproducibility of the vertical mechanism of the contact of the lower clamp portion must be good to some extent.

FIG. 3 is a perspective view specifically showing an up-and-down mechanism of the lower clamp portion 22. As shown in FIG. The contact 24 of the lower clamp portion 22 is fixed to the frame 10 via two U-shaped leaf springs 26, 26. The two leaf springs 26 are provided so as to be orthogonal to each other.
It has a restraining force in the horizontal direction, but has a degree of freedom in the vertical direction. A spring 27 provided directly below the contact 24 generates the above-mentioned clamping force.

In the vertical mechanism shown in FIG. 3, two leaf springs 26 are provided so as to be orthogonal to each other.
If a leaf spring whose direction is changed is added, the binding force is further increased, and the position reproducibility is improved.

FIG. 4 is a partial cross-sectional view showing another specific example of the up-and-down mechanism of the lower clamp portion. The contact 24 of the lower clamp portion 22 includes a bearing 16 and the bearing 16.
Is connected to a linear stage 18 composed of a rod 17 held by the above. The contact 24 is horizontally restrained by the linear stage 18. The spring 2
5 is for giving a clamping force.

The main purpose of the clamping force for supporting the sample is to prevent the sample from moving due to acceleration during the movement of the stage. However, if the clamping force is too large, the upper clamp portion may be elastically deformed, and the sample load on the upper clamp portion may be a point load instead of a surface load, which is a factor of deteriorating the drawing accuracy. That is, the clamping force needs to be small enough not to move the sample.

The first embodiment shown in FIG. 1 is a view of the clamp mechanism viewed from above. In a state where the sample is not clamped, three points of the lower clamp portions of the clamp mechanisms 14a to 14c are provided. When placed on top, the weights of the samples weighted at the respective support points are m1g, m2g, m3g (m1g
Ｍm3 is mass, g is gravitational acceleration), and the clamping force at each support point can be considered on the assumption that each support point has independent masses m1, m2, and m3.

Here, a clamp condition at one support point is considered. The mass of the sample is m, the clamping force at the lower clamp is C, the drag at the upper clamp is N, the coefficient of static friction at the lower clamp is μ1, the coefficient of static friction at the upper clamp is μu, the stage maximum acceleration If α is set, the condition that the sample does not move is mα <μ1 C + μu N... Here, in order to determine C, the margin k is defined as the following equation.

Kmα = μ2 C + μu N 2 Considering the gravitational acceleration g, And the mass is proportional to the clamping force.

As described above, the clamping force at three points is C1,
C2 and C3, and the ratio is C2: C2: C3 = m1: m2: m3... With such a clamping force ratio, the margin k of the clamping force at each support point becomes constant, and the load on the upper clamp portion is unlikely to become a point load. As a result, unnecessary bending is not given to the sample, and the drawing accuracy is not deteriorated.

The first embodiment shown in FIG. 1 is an arrangement when the own weights at the respective support points are not equal.
The arrangement in which the clamping force C is minimized is, as shown in the second embodiment shown in the top view of FIG. 5, the center of gravity of the sample 12 (point G where two dashed lines intersect) and three clamping mechanisms. 1
This is when the center of gravity of the triangle formed by the three support points 4a to 14c coincides.

Next, a description will be given of a positioning method for inserting a sample into the sample supporting mechanism having the above-mentioned configuration with reference to FIG. As shown in FIG. 6, the abutment 13 has a tapered upper portion and a cylindrical lower portion, and the boundary is located below the lower surface of the sample at the time of clamping. The alignment sequence will be described below. (1) The sample 12 is transported, and the contact 24 of the lower clamp portion
Put on top. Then, the lower clamp portion is raised (FIG. 6A). (2) Immediately before the sample 12 is clamped (several mm), the lower clamp portion is stopped. The sample 12 is pressed against the butting 13 by a pressing pin 31 on the opposite side of the butting 13 (FIG. 6B). (3) The pressing pin 31 is retracted (FIG. 6C). (4) Raise the lower clamp portion again and clamp.
At this time, the butting 13 and the sample 12 are not in contact (FIG. 6D).

According to the above sequence, the sample 12 and the abutment 13 are not in contact with each other when clamped, so that no external force acts on the sample end face, unnecessary deflection fluctuation is not given to the sample, and the drawing accuracy is deteriorated. Has the effect of not letting you do. Also,
Since the sample is pressed against the abutment just before the clamp by the operation (2), the positioning can be performed with the same accuracy as that of the related art.

Next, another positioning method for inserting a sample will be described with reference to FIG. In the positioning method shown in FIG. 7, the butting 13 is provided at the tip of the piezoelectric element 32. The piezoelectric element 32 itself is the frame 1
It is fixed to 0. When the sample 12 is pressed by the pressing pin, the butting 13 is slightly moved by the piezoelectric element 32 in the direction of the sample. After the pressing of the sample 12 is completed, the butting 13 is also retracted toward the frame 10 simultaneously with the retraction of the pressing pin. Then, the sample 12 is clamped by raising the lower clamp portion.

According to this method, since the butting 13 is moved by the piezoelectric element 32, the position reproducibility may be deteriorated. However, while the displacement of the piezoelectric element is several μm, the required positioning accuracy of the sample is several tens μm.
m to several hundreds μm, and the deterioration of the positioning accuracy of the sample due to the movement of the butting 13 can be ignored.

As described above, by using the sample support mechanism according to each of the above-described embodiments, an excessive load is not applied to the sample, and as a result, the deflection of the sample is eliminated, and the variation in the alignment accuracy between the samples is prevented. Is suppressed.

[0041]

As described above, according to the present invention, no excessive load is applied to the sample, and as a result, the deflection of the sample does not change, and the variation in the alignment accuracy between the samples is suppressed.

[Brief description of the drawings]

FIG. 1 is a top view showing the overall configuration of a sample support mechanism according to a first embodiment.

FIG. 2 is a partial sectional view showing a schematic configuration of a clamp mechanism in the sample support mechanism of FIG.

FIG. 3 is a perspective view specifically showing a vertical mechanism of a lower clamp unit in the clamp mechanism of FIG. 2;

FIG. 4 is a partial cross-sectional view showing another specific example of the up-and-down mechanism of the lower clamp unit.

FIG. 5 is a top view showing the overall configuration of a sample support mechanism according to a second embodiment.

FIG. 6 is a view for explaining a positioning method when a sample is inserted into the sample support mechanism of the present invention.

FIG. 7 is a view for explaining another alignment method for inserting a sample into the sample support mechanism of the present invention.

FIG. 8 is a perspective view of a conventional sample support mechanism.

[Explanation of symbols]

10: Frame, 11: Sample storage unit, 12: Sample, 13
a to 13c: butting, 14a to 14c: clamping mechanism, 15: grounding mechanism, 16: bearing, 17: rod,
18 Linear stage, 21 Upper clamp part, 22
Lower clamp part, 23 contact surface, 24 contact, 25 ...
Spring, 26: leaf spring, 27: spring, 31: pressing pin, 32: piezoelectric element.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ryoichi Hirano 1st station, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Inside Toshiba R & D Center

Claims (5)

[Claims] 1. A support mechanism for fixing a sample of an electron beam exposure apparatus, comprising: three clamp mechanisms for clamping a sample by sandwiching the sample from both front and back sides at different positions of the sample; A first clamp portion having a flat contact surface with the sample, and a second clamp coaxially opposed to the first clamp portion and having a convex contact surface with the sample. A sample supporting mechanism in the electron beam exposure apparatus, wherein one of the first and second clamps is movable in a normal direction of the sample. 2. The sample of one of the first and second clamps, wherein the plane of the contact surface of the first clamp with the sample is movable in the normal direction of the sample. 2. A sample support mechanism in an electron beam exposure apparatus according to claim 1, wherein a variation in positional accuracy in a plane direction is equal to or more than a variation. 3. One of the first and second clamp portions, which is movable in the normal direction of the sample, is arranged so that two or more U-shaped plate panels are shifted in phase from each other. 2. The sample support mechanism according to claim 1, wherein the mechanism has a degree of freedom in a direction normal to the sample and is constrained in the direction of the sample surface. 4. A mechanism in which one of the first and second clamp portions made movable in the normal direction of the sample has a degree of freedom in the normal direction of the sample by a mechanism comprising a rod and a bearing. 2. The sample supporting mechanism in the electron beam exposure apparatus according to claim 1, wherein the sample supporting mechanism is held in a sample surface direction. 5. A support mechanism for fixing a sample of an electron beam exposure apparatus, comprising: three clamp mechanisms for clamping a sample by sandwiching the sample from both front and back surfaces at different portions of the sample, and contacting the drawing surface of the sample. Has a grounding mechanism for
A sample support mechanism in an electron beam exposure apparatus, wherein a contact point between the ground mechanism and a drawing surface of the sample is provided in the vicinity of any one of the three clamp mechanisms.