JPS5828832A - Electron beam exposure - Google Patents

Abstract

PURPOSE:To approximate as much as possible the shape of figure depicted by the electron beam exposure to the shape originally depicted by positively utilizing that a size of rectangular form can be changed which is the characteristic of the variable rectangular electron beam exposing apparatus so as to make smaller the level difference at the connecting point of the rectangulars of rectangular electron beam at the circumference of a large size figure and to make smaller the deterioration of linearity at the circumference of a large size figure resulting from thermal change of quality of electron beam sensible material. CONSTITUTION:A figure is exposed by adjusting the shape of cross-section of electron beam so that the periphery of figure is depicted with the electron beam shaped into the rectangular cross-section having the small side and the inner part of figure is depicted with the electron beam shaped into the rectangular cross-section having the longer side. A size of rectangular electron beam used for depicting the periphery of a figure is set to 1/3 of the dimensions of the maximum rectangular electron beam.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam exposure method, and more particularly to a method for manufacturing devices for miniaturizing and increasing the density of semiconductor integrated circuits.

The important thing in integrating elements on a wafer at a high density is to reduce the size of the elements and to integrate the elements at a high density.
It is to be. According to the method using the bigaku-ro-yi technique described in Chapter 4, the size/F2 of the formed element has approached 1 micron from 2 microns. 11i, with 1 branch of secondary beam exposure, it is possible to form a bang with a 11-inch length F Zabmicron width-width tool. Semiconductor integrated circuit element slams are popular. (The pattern is, along with the ``kumen'' method, the old linearity of the bangs is also ``. However, if there is a step difference of 0.2 microns, 1i-a:], if there is a T?r, the alignment accuracy of the electrodes that form the element must also have a margin of 0.2 microns. -, V-ko's 11 (, there is a negative effect on the temperament characteristics as well.

Alpha-beam exposure equipment (A, J, 5peth etal
+J, Vac, Sci, Technol,, Vo112
, 1975. Mr. Goto (Patent Application Publication No. 1983-20391, 1983-
2.0393), but the latter uses a method of connecting rectangles to form a long pattern, so
Steps are likely to occur at the connection between rectangles, and the former is inferior to the former in terms of pattern linearity and □.

When drawing a pattern using a variable rectangular electron beam exposure device, the reasons why the directness of the connecting parts between rectangles is not improved are as follows: First, it is necessary to form a rectangular or square rectangular electron beam with accurate orthogonality and parallelism. That's a very difficult thing to do. Second, it is difficult to match the direction of the sides of the rectangular electron beam with the direction of the axis of the electron beam deflection system. Thirdly, it is difficult to match the direction of the sides of the rectangular electron beam with the direction of the axis of the sample stage movement system.

For example, one way to match the direction of the sides of a rectangular electron beam with the direction of the axis of the electron beam deflection system is to use a large reference pattern provided near the exposed sample of an electron beam exposure system, and use a large reference pattern on the long side of the reference pattern. There is a method that uses reflected electron signals obtained when scanning an edge with an electron beam with an electron beam. While looking at the backscattered electron signal diagram when the end of the pattern on the sample surface is scanned with a rectangular electron beam, the horizontal axis is the time axis, and the vertical axis is the backscattered electron intensity, the rectangular '11): Child beam ',) The direction of J is rotated with respect to the scanning direction, and the reflection 'r11' and the child signal figure have the steepest 1"r + 31: Unisu7.). In this process, the operation Those skilled in the art of n will feel at ease.At that time, the direction of the W of the rectangular surface d1 matches the direction of the long side of the base candy pattern end 1ηIX above.The same side of the standard pattern l'i15 is as follows. 'Li and C beam deflection threads do not match the j-crotch, so the direction of the sides of the rectangular electron beam must be further rotated by a certain angle.The added angle +W actually changes the pattern. Since it is a quantity that cannot be understood without one exposure, in order to determine the supplementary iTE exposure, it is necessary to carry out an exposure experiment of 11 LI [or so. However, by adjusting the time, it is possible to reduce the step between the rectangles of the electron beam to the point where it is almost impossible to measure it, but with normal adjustment,
0.0.
A step difference of about 2 microns occurs when spinning: ii&.

To solve this problem, there is a method of reducing the size of the child beam rectangle to a maximum of 1. This is IBM's EL-1 quadruple beam exposure system, which has a rectangular beam size of 2.5 microns.
, II, S, etal -*'1. 'ech
, 1) i gest of '76 IIi3DM
.

PP431-445), As the maximum rectangular dimension is made smaller, the exposure time for one ril beam becomes closer to that of a round electron beam, and the number of electron beam shots increases to expose the same area. . As a result, the exposure time increases rapidly, and the characteristics of the rectangular electron beam exposure apparatus disappear.

1) When drawing a large figure on a large rectangle with a child beam, even if the cross-sectional shape and drawing position of the electron beam to be drawn are within the specified accuracy, the linearity of the peripheral part of the large figure may deteriorate due to a cause other than the cross-sectional shape of the rectangular electron beam, and as a result, the limiting force may be limited to the rectangular dimension of the electron beam. This means that if the thermal conductivity of the substrate material supporting the electron beam-sensitive material on which the electron beam is incident and patterned is poor,
If the electron beam rectangular size is large, the electron beam sensitive material undergoes thermal deterioration.

51 The present invention is designed to reduce the difference in level between the rectangle of the double beam rectangle and the first concatenation part of the rectangle in the peripheral area of a large figure by thermal change of the double beam. In order to further reduce the ′FK change in the linearity of the peripheral part of a large figure caused by The goal is to make the shape of the figure drawn by beam exposure as close as possible to the shape of the drawn strips.

Hereinafter, the present invention will be explained based on specific embodiments with reference to the drawings. Figure 1 (al (1) l (c)) Each figure shows an example of drawing using a variable plow beam using the conventional exposure method. An example of division in which the beam is drawn in sections and the remaining portion is drawn in a rectangular shape of an appropriate thickness is shown in the ideal case where the beam rectangular shape is tilted and the electron-sensitive beam material is not subject to thermal deterioration. The reason why we try to write as much as possible with a rectangular beam with the maximum rectangular dimension is to shorten the writing time as much as possible. FIG. 1 above shows how the baton is formed.

There is a step at the connection between the rectangles, and the linearity around the figure is poor. FIG. 1 (cl) shows how the above-mentioned FIG. 1 (al) is formed when the electron beam-sensitive material undergoes thermal alteration.

Since each large 1d child beam irradiation rectangle has a rounded shape, the machining properties around the figure are poor.

Figure 2 (al (bl) is an example of writing with a variable rectangular beam according to an embodiment of the present invention. 1, and the inside of the figure is drawn using a borrowed large rectangle 'ML child beam.In this example, the amount of step difference between the rectangles due to the inclination of the rectangles shown in Fig. 1 (l) is It has decreased by at least one-third.

When the present invention is implemented, even if the conditions are far from ideal and the sensitizer beam material is altered by heat as shown in Figure 1 (cl), the r
H, in Fig. 2, in case I), kl' l zo III', '11L child beam J in the peripheral part, and) 1 ne, then 1 blue is 1/13th of the case fc) in Fig. 1, and the 2nd I In the case of J with 1 + 111, the rectangular area of the Ichi 1 beam at the periphery of the figure is reduced to 1/9th, so the thermal deterioration 111'' itself in the periphery of the figure of the sensitive N'C beam material is greatly reduced. Together, the effect i1: , ni becomes larger and a predetermined figure can be formed with a precision of a light minute.

Since the inside of the figure is drawn with the maximum rectangular size, the sensitizer beam material in that area naturally receives a lot of love.

However, in most cases, the shape of the electron-sensitive beam material required for practical use is determined by the outer periphery F';Ii of the shape shown in FIG. 2, which poses many problems.

The above explanation is for the sake of explanation, and also for the sake of clarity.
F! , , the r('fi ++lr+ method of a fixed exposure figure and a variable rectangular Ichiko beam has been described.

For example, in Figure 1 and Figure 2 (r), the length (1") was originally considered to be larger than the thick electron beam rectangular dimension, but it does not have to be larger than one side and kJ two sides. The present invention is also effective for shapes that are not as large as the maximum electron beam rectangle. Even if L1' is smaller than the maximum rectangular dimension allowed by the optical device, the 4 beam exposure method of the present invention is effective. Draw a rectangle with a child beam on a rectangle ``+'' that is large enough to prevent the beam material from fading significantly due to thermal deterioration, and make the inside of the figure as large a rectangle as possible)
The purpose is to write with 61 beams.

The reason why the inside of the figure is drawn using a rectangular electron beam as large as possible is that it is desired to shorten the electron beam drawing time as much as possible. The reason for applying 1S (1S) to the processing method for the inside of this figure is the same for the electron beam exposure method when the electron beam rectangle is tilted or the orthogonality is poor. Although the rectangular dimensions have been temporarily reduced to one-third, this is also to make the explanation more specific, and it goes without saying that the vertical and horizontal lengths of the rectangular dimensions should be determined according to the degree of linearity of the peripheral area of the figure. It is.

9-

[Brief explanation of drawings]

1st izuI fal fhl (cl diagrams, 4.,
:y;? 9) Explaining the necessity of
1, I ~ σr: East's theory of the exposure method of the variable J-shaped aperture 'lF1 beam, four times J) 1, · fl, the thickest rectangle of lJ1 in Figure 1 (;l) is This is the size of the electron beam. Figure 14'r, 2 (at and 21' flash (t)) is an explanatory diagram showing the eleventh aspect of the present invention. H1-

Claims (1)

[Claims] In the electron beam Fukimoto method using an electron beam with a variable rectangular cross section of M, in order to draw the peripheral part of the drawing figure, draw with an electron beam shaped into a rectangular cross section with a small side length,
An electron beam exposure method in which the cross-sectional shape of an electron beam is adjusted so that the inside of a figure to be drawn is exposed with an electron beam formed into a rectangular cross-section with a large side length.