JPS5941834A - Electron-beam exposure method - Google Patents

Abstract

PURPOSE:To reduce edge roughness by positively utilizing a proximity effect of electron beams and giving the recessed section of an oblique line section the quantity of a dose more than other sections. CONSTITUTION:Size in the rectangular direction is made larger than raster width in the raster scanning of shaping beams 4. For example, a designed exposure pattern 1 is exposed by the shaping beams 4, and size in the direction rectangular to the direction of the raster scanning of the shaping beams 4 shall be 1.5mum that is, beam size is equal to (address size)X1.5. A drawing pattern 7 is obtained by developing the exposed resist, and swellings are generated in the pattern owing to the proximity effect in adjacent sections 8a, 8b by the presence of double exposure regions 6. The recessed sections of the adjacent sections 8a receive the proximity effect more than the adjacent sections 8b because only non-pattern sections at 90 deg. including an angle of 270 deg. in the pattern section is present in the recessed sections of the adjacent sections 8a. Accordingly, the irregularities of the oblique line sections extends over 0.3mum, and a side rectangular to the raster scanning can be inhibited up to the edge roughness of 0.2mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electron beam exposure method using a shaped beam, and particularly to an electron beam exposure method suitable for drawing diagonal lines.

[Technical background of the invention and its problems]

Recently, electron V using a shaped beam has been used to form fine nof turns on samples such as semiconductor wafers and reticles.
-M exposure equipment has been developed. This device uses the so-called rask scanning method, which scans the beam scanning range (field) from end to end regardless of the presence or absence of a main turn, and irradiates the beam on the patterned portion, and the There is also a so-called spectral scanning method in which a beam is brought to the surface and irradiated. Among these scanning methods, the rask scanning method has the advantage of being able to obtain high throughput when the minimum line width is relatively large. For this reason, when drawing a reticle or the like, the sirasta scanning method is more advantageous than the pectoral scanning method, and electron beam exposure apparatuses of the rask scanning method are often used. However, when drawing a pattern by rask-scanning a rectangular shaped beam using a rask-scanning electron beam exposure device, if the pattern has a hatched area, the unevenness of the hatched area will be severe and edge roughness will increase. There was a problem.

This problem will be explained below with reference to FIGS. 1 and 2. When drawing a pattern including a diagonal line part by rask scanning using a square or rectangular shaped beam, first, as shown in FIG. 1, a designed exposure, each turn 1, is exposed with the shaped beam 2 on the resist. Here, the dimension of the shaped beam 2 in the direction perpendicular to the rask scanning direction was set to 1 [μm], and the beam dimension was defined as the near address dimension. Next, by developing the resist, a drawn f-turn 3 as shown in FIG. 2 is obtained. In this case, it has been experimentally found that an unevenness of approximately 0.6 [μm] is formed in the shaded area. Drawing no f turn 3
The reason why is not the same as the designed exposure pattern 1 shown by the broken line is because the proximity effect of the electron beam and the corner curvature of the beam are finite.

In this way, with the conventional method, although it is possible to obtain accurate elbow turns on the sides perpendicular to and parallel to the rask scan, there is a problem in that relatively large edge roughness occurs in the shaded areas. [Object of the Invention] An object of the present invention is to provide an electron beam exposure method that can reduce edge roughness in the shaded area and is effective in drawing the shaded area when drawing a shiba pattern by rask scanning using a shaped beam. It is in.

[Summary of the invention]

The gist of the present invention is to reduce the nip roughness by positively utilizing the proximity effect of the electron beam and applying a large dose to the diagonally shaded concave portion.

That is, the present invention provides an electron beam exposure method in which a resist on a sample is rask-scanned with a shaped beam to expose a desired turn on the resist, and the dimension in the direction perpendicular to the rask scanning direction of the shaped beam is set to be equal to the raster width. This method also increases the size of the area.

〔Effect of the invention〕

According to the present invention, a large dose can be applied to the concave portion of the shaded area, and the unevenness of the 74 turns of the shaded area can be reduced by K. That is, the nip roughness in the diagonal line portion can be extremely reduced, which is extremely effective in drawing patterns including diagonal lines.

[Embodiments of the invention]

FIGS. 3 and 4 are schematic diagrams for explaining one embodiment of the method of the present invention, respectively. First, the designed exposure pattern 1 was exposed with a shaped beam 4 as shown in FIG.

Here, the dimension of the shaped beam 4 in the direction perpendicular to the rask scanning direction was set to 1.5 [:m], that is, the beam dimension near address dimension x 1.5. In FIG. 3, a dashed double-dashed line 5 indicates an actual exposure area, and a hatched area 6 indicates a double exposure area.

Next, by developing the exposed resist in the same manner as in the conventional method, a drawing pattern 7 as shown in FIG. 3 was obtained. That is, due to the existence of the double exposure area 6, the area 6
The neighborhood of 8&.

In 8b, a bulge occurs in the pattern due to the proximity effect. In the concave portion of the adjacent portion 8a, since the pattern portion includes an angle of 270 degrees and the non-pattern portion has only a 90 degree angle, the proximity effect is larger in the recessed portion than in the adjacent portion 8b. With this, the unevenness of the shaded area is 0.3 [μm], and the side perpendicular to the rask scan is 0.2 [μm].
The edge roughness could be suppressed to [μm].

Also, by exposing with a dimension larger than the address dimension, the pattern swells on the side parallel to the rask scan, but since the average dose increases, the resist development time can be shortened to 1.0 It was possible to suppress the increase in the tan width to 79 [μm] or less. Furthermore, by shortening the development time, the roundness of the convex portions 8c of the pattern was improved more than before. Furthermore, when the beam dimension was set to address dimension x 2, it was possible to suppress the diagonal line unevenness to 0.2 [μm] or less.

In this way, according to the method of this embodiment, address size x 1.
By exposing 4 turns using a shaped beam of
2. Therefore, it is extremely effective for drawing patterns including diagonal lines.

Note that the present invention is not limited to the embodiments described above. For example, the dimension of the shaped beam in the direction perpendicular to the raster scan is not limited to the raster width X 1.5 K, but may be larger than the raster width. However, according to experiments by the inventors, the above beam dimension is raster width x 1.1
If the width is small, the reduction in nip roughness mentioned above cannot be expected, and if the beam size is increased by 2 times the raster width, the bulge of the /4 turn on the side parallel to the rask scan is so large that it cannot be ignored. It was confirmed that Therefore, the dimension of the shaped beam may preferably be 1.1 to 2 times the address dimension. In the embodiment, the case where a positive type resist is used has been described, but it goes without saying that a negative type resist may also be used.

In the case of a negative resist, it is more effective in reducing nip roughness because it is subject to the above-mentioned proximity effect more than a positive resist. Further, the shape of the shaped beam, the shape of the exposure t4 turn, etc. may be determined as appropriate according to the specifications. others,
Various modifications can be made without departing from the spirit of the invention.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic diagrams for explaining a conventional method, respectively, and FIGS. 3 and 4 are schematic diagrams for explaining an electron beam exposure method according to an embodiment of the present invention, respectively. 1... Crotch exposure/or turn, 2, 4... Shaped beam, 3... Drawing pattern, 5, 7... Actual exposure pattern, 6... Double exposure area. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Continued from page 1 Applicant Toshiba Machine Co., Ltd. 4-2-11 Ginza, Chuo-ku, Tokyo

Claims (3)

[Claims] (1) In an electron beam exposure method that uses a shaped beam and scans a resist on a sample with the shaped beam to expose the resist in a desired pattern, the dimension in the direction perpendicular to the rask scan of the shaped beam is set to be equal to the raster width. An electron beam exposure method characterized by increasing the size of the beam. (2) The electron beam exposure method according to claim 1, wherein the dimension of the shaped beam in the direction perpendicular to raster scanning is set to 1.1 to 2 times the raster width. (3) The electron beam exposure method according to claim 1, wherein a negative resist is used as the resist.