JPH0217628A - Method of forming resist pattern - Google Patents

Abstract

PURPOSE:To make it possible to form a fine resist pattern of 1mum or thinner by adjusting rotation correction of a rectangular formed slit in either horizontal or vertical direction and then drawing by connecting rectangular electronic beams with the adjusted direction as a longer side in an electronic beam drawing device of a rectangular formation system. CONSTITUTION:A negative-type electronic beam resist 11 is rotated and applied on a photomask substrate 12. Alignment and development are performed using an electronic beam aligner and a resist pattern 15 is formed. If the resist pattern 15 as shown in the figure was formed at this point, the orthogonality theta of the first and second aperture 5, 7 corresponds to the orthogonality theta, phi of the resist pattern 15, but these orthogonalities do not match with each other. Hence, the rotation of the apertures 5, 7 is corrected to adjust in the vertical direction. Then, it is divided to longitudinal rectangular shots, and electronic beams having a rectangular cross-sectional shape with the direction in which adjustment is made as a longer side are arrayed and drawing is carried out. This makes it possible to form a fine resist pattern of submicrons by a conventional device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a resist pattern in the production of high-density integrated circuits such as LSIs and VLSIs, or photomasks used in the production thereof.

[Conventional technology]

As is well known, in recent years there has been an increasing demand for higher performance and higher integration of semiconductor integrated circuits. Therefore, efforts are being made to establish ultra-fine pattern processing techniques by lithography using electron beams, soft X-rays, ion beams, etc. instead of conventional photolithography using ultraviolet rays.

Particularly in the production of photomasks, electron beam lithography has already been put into practical use industrially, and direct FM imaging using electron beams on a substrate has also been attempted.

On the other hand, the resist materials used to enable such ultra-fine lithography technology must also have corresponding characteristics, and the resist process is also extremely important, while at the same time increasing the requirements for electron beam exposure equipment. The accuracy of the drawing will also become stricter.

Many types of electron beam exposure equipment have been developed, but these are raster scanning type, which uses an electron beam scanning method to scan the entire deflectable area and turn on the beam only to the pattern area, and the raster scanning type, which uses the electron beam scanning method to turn on the beam only to the pattern area. There is a vector scanning type that scans by addressing. In addition, due to the shape of the electron beam, we have a Gaussian distribution beam (circular) that reduces and projects the crossover image of the electron beam formed by the electron gun, and a shaping aperture provided in the middle to make it into a rectangular cross-section. There is a variable shaped beam that draws images while changing.

Among these, an electron beam exposure system that uses a vector scanning type electron beam scanning method and a variable shaped beam vector scanning type that combines a variable shaped beam as the electron beam shape has the fastest drawing speed (high throughput).
In particular, it is used for direct electron beam writing on wafer substrates coated with electron beam resist.

[Problem to be solved by the invention]

However, it is difficult to form a cross-sectional shape of an electron beam formed by a rectangular-forming type electron VAn optical device into a rectangle with accurate right-angled corners, and the cross-sectional shape of the electron beam is usually slightly deviated from a rectangular shape. Performs electron beam exposure. Therefore, a rectangular resist pattern image formed by electron beam exposure also does not have accurate right angles. Particularly, in the case of fine patterns, there is a problem in that the degree of orthogonality of the resist pattern becomes noticeable.

Therefore, an object of the present invention is to improve the degree of orthogonality of a rectangular cross-section of an electron beam formed by a rectangular-forming electron beam exposure apparatus.

[Means to solve the problem]

Therefore, as a result of various studies to solve the above problems, the present invention adjusts the rotational correction of the rectangular slit to either the horizontal or vertical direction, and sets the direction in which the adjustment is performed as the long side. The present invention was completed by finding a way to solve the above problems by arranging electron beams having a rectangular cross-sectional shape and performing electron beam lithography.

In the above content, the maximum size of the rectangle of the electron beam is 2 to 20 μm on the long side and 0°5 to IO μm on the short side.
It is desirable that

[Effect]

As described above, since a rectangular resist pattern with good orthogonality can be formed using a rectangular forming type electron beam exposure apparatus, a resist pattern with very high precision can be obtained. Furthermore, even in a submicron resist pattern of 1 μm or less, a pattern with very little roughness can be obtained.

〔Example] Examples will be described below with reference to the drawings.

FIG. 1(a) is a schematic cross-sectional view of an electron beam exposure apparatus according to the present invention, FIG. 1(b) is a top view of an aperture 5.7 for forming an electron beam into a rectangular shape, and FIG. FIG. 3 is a diagram showing a resist pattern drawn and formed by the electron beam drawing device shown in the figure, and FIG. 3 is a diagram showing a resist pattern drawn and formed by the electron beam drawing device after mechanically correcting the rotation of the aperture 5.7. It is.

In the first session, 1 is an electron gun, 2 is an electron beam, 3 is a blanking electrode, 4 is an irradiation lens, 5 is a first aperture, 6
is a molded lens, 7 is a second aperture, 8 is a reduction lens,
9 is a projection lens, 10 is a positioning deflector, 11 is an electron beam resist, 12 is a photomask blank, 13 and 14 are electron beam passage parts, 15 is a resist pattern image, and θ and φ indicate the orthogonality of the aperture.

As shown in FIG. 1(a), the rectangular forming type electron beam exposure apparatus includes a blanking electrode 3, an irradiation lens 4, a shaping lens 6, a reduction lens 8, a projection lens 9, and a positioning deflector lO.
An electron beam 2 emitted from an electron gun 1 is exposed to a photomask substrate 12 on which a negative electron beam resist 11 is spin-coated. In this electron optical system, a first aperture 5 is provided between the irradiation lens 4 and the molded lens 6;
By arranging second apertures between the first aperture 5 and the reduction lens 8, a rectangular resist pattern is formed by combining the first aperture 5 and the second aperture. FIG. 1(b) is an enlarged top view of the first aperture 5 and the second aperture.
．． 14 has angles θ and φ.

The procedure for forming a resist pattern using the above-mentioned rectangular-forming electron beam exposure apparatus is as follows: First, a negative electron beam resist 11 is spin-coated onto the photomask substrate 12, and then exposed and developed using the electron beam exposure apparatus.

After that, a resist pattern is formed. As the negative electron beam resist, for example, a resist whose main component is chloromethylated polystyrene (trade name: CMS-E manufactured by Takuso Co., Ltd.) is used.
X (R)') is used.

Now, assuming that the resist pattern 15 shown in FIG. 2 is formed, the orthogonality θ and φ between the first aperture 5 and the second aperture 5 in FIGS. 1-) are the orthogonality of the resist pattern 15 in FIG. θ′ and φ′, but their orthogonality degrees do not match.

Therefore, in the present invention, first, the first aperture 5 and the second aperture 5 are
The aperture is rotated and corrected to align it vertically as shown in FIG. After performing the mechanical rotation correction in this way, the pattern shown in Fig. 4 is divided into vertically elongated rectangular shots as shown in Fig. 5, and the cross-sectional shape of the rectangle whose long side is in the direction in which alignment was performed is created. Electron beam drawing is performed by lining up electron beams with . By doing so, the edge roughness of the drawn pattern could be reduced to 0.02 μm or less. The maximum size of the rectangular shot was 10 μm in length and 2 μm in width.

In addition, in the above embodiment, the rotation correction is performed in the vertical direction, but it goes without saying that the rotation correction may be performed in the horizontal direction.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, 11
This method has the advantage that a fine resist pattern of submicron size of 1 m or less can be formed using a conventional rectangular forming type electron beam exposure apparatus. Further, there is an effect that the joint accuracy between the rectangles of the electron beam is improved and the edge roughness of a fine resist pattern is reduced.

[Brief explanation of the drawing]

FIG. 1(a) is a schematic cross-sectional view of an electron beam exposure apparatus according to the present invention, FIG. 1(b) is a top view of an aperture 5.7 for forming an electron beam into a rectangular shape, and FIG. Figure 3 shows a resist pattern drawn and formed by the electron beam drawing device shown in the figure, after mechanically correcting the rotation of the aperture 5.7. Figure 4 is a diagram showing the drawing pattern, Figure 5 is a diagram showing the drawing pattern.
The figure shows a drawing pattern after being divided into rectangular shots. DESCRIPTION OF SYMBOLS 1... Electron gun, 2... Electron beam, 3... Blanking electrode, 4... Irradiation lens, 5... First aperture, 6... Molding lens, 7... Second Aperture, 8.
... Reduction lens, 9... Projection lens, 10... Positioning deflector, 11... Electron beam resist, 12... Photomask blank, 13.14... Electron beam passage section,
15...Resist pattern image. Applicant: Dai Nippon Printing Co., Ltd.

Claims (1)

[Claims] (1) In a rectangular forming type electron beam lithography apparatus, after adjusting the rotational correction of the rectangular forming slit in either the horizontal or vertical direction, a rectangular cross-sectional shape whose long side is in the direction in which the alignment was performed 1. A method for forming a resist pattern, which comprises obtaining a rectangular resist pattern image on a drawing substrate by performing electron beam drawing using an electron beam having a