JPH0158652B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a mask support in an electron beam lithography apparatus or the like.

[Background of the invention]

In an electron beam lithography system, the variation in the height direction of the drawing surface of the mask, that is, the distance from the deflection lens of the electron optical system (hereinafter referred to as Z variation), is directly related to the size of the drawing pattern. When the stage on which the is mounted is moved in the X and Y directions, it is necessary to minimize the Z fluctuation within the drawing area to, for example, about 3 μm. In addition, the height of the mounting surface of the standard mark, which determines the origin of the drawing position, calibrates the pattern size, and serves as the origin of movement, differs from the height of the drawing mask for the same reason. It is also one of the reasons why it gets worse. The main factors related to Z fluctuation are XY
The flatness of the moving guide surface, the parallelism between the XY guide surface of the moving stage on which the mask is placed and the drawing surface, the flatness of the drawing surface, and combinations of the above are considered, but the present invention is the most technically effective of the above. This is related to a number of problems.

Generally, in an electron beam lithography system, when a mask is fed onto an XY stage in a vacuum by a mask supply device, it is difficult to handle and transport a glass mask as it is, so the mask is usually placed in a mask holder called a cassette. Normally, each cassette is transported.

FIG. 1 is a sectional view illustrating a conventional mask supporter. In this mask supporter, the flatness (height) adjustment described above is performed by placing the mask 1 in the first position of the cassette 2.
An indirect reference surface method was used in which the cassette was pressed against the reference surface 3 using a leaf spring 6 or the like, and the cassette was pressed against a second reference surface 5 attached to the upper part of the cassette holder 4. However, this method had the following drawbacks. One cassette with a reference surface made with high mechanical precision is required for each mask. It is an indirect reference surface method, and the flatness of the two surfaces is related to the flatness of the drawing section, so it is difficult to obtain better flatness (same height accuracy). Since the pressure is applied using a spring, it is difficult to make the pressure even and it is difficult to make it come into close contact with the reference surface.

[Purpose of the invention]

The present invention eliminates the drawbacks of the conventional mask holder and provides a highly accurate mask holder.

[Summary of the invention]

In order to achieve the above object, the present invention provides a reference face plate having 4-point reference pins at the same height as the surface that contacts the cassette holder on the table, and is configured so that the mask is directly pressed against the 4-point pins. It is.

[Embodiments of the invention]

``Hereinafter, the present invention will be explained with reference to examples.

FIG. 2 is a sectional view illustrating an embodiment of the present invention, and FIG. 3 is a plan view seen from 26A and 26B in FIG. 2 toward the bottom of the drawing, excluding the standard mark 18 portion. The operation after the mask 12 is stored in the cassette holder 20 will be explained with reference to FIGS. 2 and 3.

Reference pins 11 are attached to the reference face plate 19 shown in FIG. 2 at positions corresponding to the four corners of the mask 12.

As shown in Figure 3, the four reference pins 11 at the four corners
A, 11B, 11C, and 11D are for regulating the flatness of the mask.Geometrically, three reference pins may be sufficient, but considering the directionality of the mask, four reference pins are used.
It has a point structure, and the reference pin 11 is the only member representing the reference surface of the reference face plate 19.

The reference surface of the reference face plate 19 is processed by lapping or the like with the surface in contact with the cassette holder 20, so that it is easy to obtain the same plane. Further, since the above-mentioned lapping process is performed between the standard mark 18 having the function of dimensional calibration and position origin, the structure is such that they are on the same plane. Next, the operation of the mask to be pressed against the reference pins 11A, 11B, 11C, and 11D attached to the reference face plate 19 will be explained.

The mask 12 is pressed against the reference pin by the second
It consists of the structure shown in the figure. That is, the mask up/down plate spring 14 for pressing the mask 12, the bellows 13 that moves the mask up/down plate spring 14 up and down, and a pressure mechanism (not shown) for pressurizing or depressurizing the inside of the bellows 13 are used. This constitutes a first pressing means. Next, the operation and structure will be explained in detail.

Mask upper and lower plate spring 1 in the first pressing means
Four resin pins 15 are attached to the vicinity of the tips of the pins 4, which pass through the cassette 16 and directly press the mask 12 from the bottom to the top in FIG.
As a result, the upper surface side of the mask 12 is connected to the reference pin 11.
A, 11B, 11C, and 11D, and the upper surface of the mask 12 can be configured to be flush with the reference face plate 19.

In order to directly press the lower surface of the mask 12 with the resin pins 15, it is necessary to form a large hole 22 on the back surface of the cassette 16 as shown in FIG. The position of this large hole 22 corresponds to the reference pins 11A, 11B, 11C, and 11D shown in FIG.

In the above structure, since the cassette 16 is not fixed, the mask upper and lower plate springs 1 are fixed as shown in FIG.
The cassette 16 is pressed and held against the reference face plate 19 by a second pressing means consisting of a leaf spring 17 placed on the outside of the cassette 4 and a holding pin 23 attached near its tip.

Thereby, the upper surface of the mask 12 can be easily aligned with the reference face plate 19. The number in the diagram is the second
The figures are basically numbered.

By the procedure described above, the mask 12 in the cassette 16 can be pressed against the reference face plate 19 of the mask support mechanism.

Note that the spring 24 holds the mask 12 in the cassette 16.
This is for pressing against the two right-angled sides of the recess of the cassette when placing it in the recess of the cassette. The mask 12 and cassette 16, which have been integrated in this way, are loaded onto the cassette holder 2 by a cassette loading mechanism (not shown).
Therefore, it is set to 0. At this time, the spring 25 presses it against one side of the cassette holder. These two springs allow rough alignment of the mask on the stage.

The mask support mechanism with the above structure is mounted on table 2.
1 and moves in the X-axis or Y-axis direction to operate as a drawing stage or the like.

〔Effect of the invention〕

As described above, according to the present invention, the following advantages can be obtained.

The cassette can now simply hold a mask and does not require any mechanical precision. Since the reference face plate 19 is on the same plane and has a convex surface, a surface with good flatness can be easily obtained by lapping or the like. The reference surface is one plane, and the contact surface of the reference face plate on the cassette holder 20 side to which the reference surface is attached can be machined in combination with the lower table 21. Therefore, the conditions for reducing the above-mentioned Z fluctuation, that is, the table and cassette holder Parallelism can now be achieved easily when assembled. Since the stage itself is in a vacuum, when pressing the mask against the reference surface, that is, when raising it upward, the vacuum must be leaked, and the pressing pressure is constant, the time is short, and the reproducibility is better than the spring. Now it can be pressed evenly. In addition, cassettes usually have a mechanism that presses the mask against two right-angled sides in order to draw a pattern at a fixed position on the mask, but by moving the cassette up and down each time, this function can be maintained and the weight of the cassette can be reduced. It is now possible to prevent the mask from hanging around the mask and deforming it. Furthermore, since the standard mark 18, Faraday cup, beam diameter measuring element, etc. arranged at the same height as the mask can all be arranged on one reference face plate, it is easy to replace these elements. It is now easier to modify, add to, and replace the reference plate after drawing a certain number of sheets.

As a result, a highly accurate mask supporter could be easily realized, and its function as a moving stage could be enhanced.

[Brief explanation of drawings]

FIG. 1 is a sectional view illustrating a conventional mask supporter, FIG. 2 is a sectional view illustrating an embodiment of the present invention, and FIG. FIG. 11... Reference pin, 12... Mask, 13... Bellows, 14, 17... Leaf spring, 15... Resin pin, 16
...cassette.

Claims (1)

[Claims] 1. The mask 12 is mounted on a moving stage configured to be able to move the mask 12 and a cassette 16 for storing the mask in the XY axis directions on a table 21 having a cassette holder 20 for holding the cassette. The first pressing means 13, 14, 15 which presses the cassette 16 against the reference face plate 19 provided on the table 21 and the reference face plate 19 also provided on the table 21.
second pressing means 13, 17, 2 for pressing against
3, wherein the first and second pressing means press the mask 12 and the cassette 16 independently.