JPH038321A - Lithography for minute width pattern - Google Patents

Abstract

PURPOSE:To reduce deformation of a pattern at a seam between shots and to form an accurate pattern by deviating a minute lithographic pattern at each predetermined amount longitudinally at each shot, and carrying out an electron beam lithography. CONSTITUTION:For electron beam lithography for a slender pattern having a minute width, the shape of the beam is formed in a basic pattern of a predetermined size. The longitudinal direction of the slender pattern is set to a x- direction, the length of the basic pattern in the x-direction component is xd, the position is deviated at each xd/n (n is integer number of 3 or more) in the x-direction at each shot, and electron beam lithography is carried out. For example, when the basic pattern has 0.4mum of width and xd=0.5mum of length in case of n=5, the lithographic process is carried out while the pattern is moved by 0.1mum in the x-direction at each shot.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to a method of drawing a pattern with a fine width, and more specifically, to a method of drawing a pattern with a fine width using a variable shaping type electron beam writing apparatus.

[Conventional Technology J Conventionally, lithography technology at VLSI manufacturing sites was
A light exposure method was mainly used.

However, in order to further increase the integration density of VLSI, finer resolution is required, and electron beam lithography is attracting attention. In particular, the variable shaping electron beam lithography system, which can draw rectangles up to a certain size at once, has greatly improved processing capacity. A conceptual diagram of an electron optical system is shown, and FIG. 3 is an example of a conventional drawing method when drawing a thin line pattern with a minute width using a variable shaping electron beam drawing device. It is.

In Figure 2 (a), (1) is an electron gun, (2) is a first diaphragm called an aperture (hereinafter referred to as the first aperture), (3) is a polarizer, and (4) is a second diaphragm (hereinafter referred to as the first aperture). Second
(referred to as aperture), (5) is a reduction lens, (6)
is an objective lens, (7) is an electrostatic polarizer, (8) is an electromagnetic polarizer, and (9) is a material (10) is a stage. Electron gun (
The electron beam from 1) passes through two apertures (2) with rectangular holes.

(4) is formed into a rectangle of the required size, focused by a reduction lens (5) and an objective lens (6), and placed on a stage (10) by an electrostatic polarizer (7) and an electromagnetic polarizer (8). The material (9) is irradiated at a predetermined position. The beam shape is formed using two apertures (2) and (4).
A polarizer (3) provided between the electron beam formed by the first aperture (2) and the second aperture (4)
Change the degree of overlapping and form it into a rectangle of a predetermined size. At that time, as shown in FIG. 2(b), the first aperture (2)
is the opening of (AI), and the second aperture (4) is (A2)
, and two apertures (AI), (
The electron beam is shaped into a rectangle of a predetermined size by the rectangle (A3) formed by overlapping A2).

Now, when drawing a thin line pattern with a minute width as shown in FIG. 3(a) using such a variable shaping type electron beam drawing device, as shown in FIG. 3(b), Divide and draw into the maximum shot size determined by device limitations and drawing time.

For example, if the design pattern shown in FIG. 3(a) is 1 μm wide and 16 μm long, and the maximum shot size of FIG. 3(b) is determined to be 4 μm, the width IIIm,
It is divided into four basic patterns each having a length of 4 μm, and electron beam writing is performed for each divided basic pattern.

At this time, the electron beam shape of the variable shaping electron beam lithography system can be adjusted to a width of 1 by adjusting the aperture of 2
Form into a rectangle with a μ mark and a length of 4 μm.

[Problems to be Solved by the Invention] However, the shape of the electron beam is not necessarily a perfect rectangle, depending on the adjustment of the aperture that shapes the electron beam into a rectangular shape, as shown in FIG. 3(C). It includes some asymmetry and rotation as shown in Figure 3(d).

Furthermore, problems with asymmetry and rotation tend to be exacerbated by contamination of the aperture and the like. Therefore, when a thin line pattern with a minute width is drawn with an electron beam using the conventional technique described above, the pattern formed after drawing is a third-dimensional pattern.
As shown in Figure (e), the problem is that the seams between shots (basic patterns) appear prominently and pattern accuracy deteriorates.Thin line-shaped patterns with such minute widths are not suitable for transistor gates. It is often used as a pattern, but even a slight deformation of the joint, not to mention disconnection at the shot joint, can have a big impact on the performance of the transistor.
give.

This invention was made in order to solve these conventional problems, and the pattern after electron beam drawing is a thin line pattern having a width of 9M with little deformation at the shot joint. An object of the present invention is to provide an electron beam writing method that produces a pattern closer to a designed pattern.

[Means for Solving the Problems] In order to achieve the above object, a method for drawing a fine width pattern according to the present invention uses a variable shaping electron beam drawing apparatus to form an electron beam into a rectangular shape of a predetermined size. When molding into a basic pattern, the longitudinal direction of the fine width pattern is the X direction, and the X direction component length of the basic pattern is Xd, the position of the fine width pattern is Electron beam lithography is performed by shifting the distance by an integer (integer).

[Operation J] That is, in this invention, when drawing a fine line pattern with an electron beam, the position of the pattern is shifted for each shot using a variable shaping electron beam drawing apparatus, as described above. Therefore, at the joint part of the shot, drawings of parts other than the joint part of the shots several times before and after the joint part are overlapped. Therefore, in the finally formed pattern, seams between shots do not appear conspicuously as in the prior art. An embodiment will be described in detail with reference to FIG.

The case where a thin line-shaped design pattern having a width of 0.4 μm, for example, as shown in FIG. 1(a) is written by a variable shaping type electron beam drawing device will be described with reference to FIG. 1(b).

First, the electron beam shape is formed into a rectangular basic pattern of a predetermined size (in this case, width 0.4 μm and length 0.5 μm) by adjusting two apertures. In this case, if the longitudinal direction of the fine width pattern is the X direction and the X direction component length of the basic pattern is Xd, then X cl
= 0.5 μ field. Next, electron beam lithography is performed by shifting the position in the X direction by Xd/n (n is an integer of 3 or more) for each shot, but in this example, the case where n = 5 will be explained. . That is,
Drawing is performed while shifting each shot by 0.1 μm in the X direction. Also, chemically amplified resist l-8AL-60 is used as a resist.
1, the exposure amount is normally 4μ coulombs/d in the conventional technology, but in the embodiment of this invention, drawing is performed while shifting each shot by 175, so the exposure amount is 0.8μ coulombs/d of 115. /d.

As described above, according to the embodiment of the present invention, when performing electron beam writing of a thin line pattern having a minute width, writing is performed while shifting the pattern by 115 shots for each shot, so the writing overlaps, so that one shot cannot be drawn. The exposure amount per unit can be reduced to 115 of the conventional technology. Also, as shown in Figure 1(b), considering the m-th shot, the seam on the left side of the figure overlaps the seam on the right side of the m-5th shot, but from the m-4th shot Drawing of parts other than the seam part in the four shots up to the m-1th shot is performed overlappingly. Similarly, the seam on the right side of the 1st shot of tI overlaps with the seam on the left side of the 7th yacht of the m + 5th shot, but the seam on the right side of the 7th shot of the are drawn overlappingly. Therefore, in the final formation Sarel pattern,
Seams between shots no longer appear,
Pattern accuracy is improved.

In addition, in the above embodiment, n=5 was explained, so 1
Electron beam lithography was performed by shifting the shots by 115, but the larger n (n is an integer of 3 or more) and the smaller the amount of shot shift (Xd/n), the less the deformation of the pattern at the shot joint. It becomes less. Therefore, the greater the accuracy requirement, the larger n (an integer of 3 or more) is set, and the amount (Xd/n) by which the position is shifted for each shot is set smaller. Furthermore, in the above embodiment, the chemically amplified resist 1-8AL-
Although 601 was used, other resists may be used.

[Effects of the Invention J As described in detail above, according to the present invention, when drawing a narrow iron pattern with a variable shaping type electron beam drawing device, the position of the iron beam pattern is changed in the X direction for each shot by Xd/n (where n is 3
Since electron beam lithography is performed by shifting the pattern by an integer (the above integer), there is little deformation of the pattern at the joint between shots, and a highly accurate pattern closer to the designed pattern can be formed.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining an electron beam lithography method as an embodiment of the present invention, FIG. FIG. 2 is a diagram illustrating an example of a drawing method using technology. Figure 1 (a) To the role player 〇 turn 04μ Yu I ((? 7+-50B shot

Claims (1)

[Claims] When drawing a fine width pattern using a variable shaping type electron beam drawing device, the electron beam shape is shaped into a rectangular basic pattern of a predetermined size, the longitudinal direction of the fine width pattern is the X direction, and the width of the basic pattern is A method for drawing a fine-width pattern, characterized in that, when the X-direction component length is Xd, the position is shifted in the X-direction by Xd/n (n is an integer of 3 or more) for each shot.