JPS606087B2 - Electron beam exposure method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam exposure apparatus having a deflection function, which allows exposure time to be significantly shortened.

In electron beam exposure with a deflection function, a rectangular pattern 1 as shown in Fig. 1 is used as exposure data from a computer.
By giving the positional coordinates X, , Y and sizes X2, Y2 of one corner of , a pattern with the desired position and size is drawn and the resist on the wafer is exposed.

Among the electron beam exposure methods that have a deflection function, the most common is flying.

Called the spot method, this beam focuses an electron beam as a spot on the resist surface. This method draws a figure by scanning a spot with a deflector. flying. FIG. 2 shows a simple block diagram of a scanning control section of an exposure apparatus using a spot method. When the positional coordinates X, , Y and sizes X2, Y2 of one corner of the rectangular pattern are given in digital quantities by the computer, they are entered into the corresponding registers 2 to 6, respectively. Generally, the clock 6 depends on the scanning speed of the beam spot and its frequency can be selected. While telling the clock number with the counter 7, the value of the counter 7 and the value of X2 are compared with the comparator 8.
The values of the counters are converted into analog quantities by DA converters 9 and 10, and are added and intensified by an intensifier 11, and then supplied to a deflector in the X direction. The same goes for the Y direction, while telling the counter 12 the match signal that is generated every time one line is written in the X direction.
The value of the counter and the value of Y2 are compared by the comparator 13, and the value of Y and the counter 12 are converted into analog quantities by the DA converters 14 and 15 until the two values match. They are added together, multiplied, and supplied to the Y-direction deflector. Beam deflected in the x and y directions. The spot advances in the vector-combined direction, and a pattern having a desired position and size is exposed. Next, as another method of electron beam exposure having a deflection function, there is a method called "rectangular pattern exposure method."

In other words, using two rectangular diaphragms, the size of the rectangular beam is determined by a deflector located between them, the obtained rectangular beam is reduced and projected, and then deflected by the deflector again to control the position of the rectangular beam. In this method, the size and position of the pattern are determined by separate deflectors, so the configuration of the control section is simple, as shown in Figure 3.This method transfers data for each rectangular pattern. However, since a rectangular area is exposed at once according to the clock, the exposure time is shorter than that of the flying spot method.

However, due to the limitations of the optical system, the size of the rectangular pattern that can be exposed at one time cannot be limited to a maximum of about 10. Therefore, when exposing, it becomes necessary to divide the pattern into many rectangles and expose them. The amount of data that needs to be transferred is enormous. In the end, in any of the above exposure systems, as patterns become finer and more complex, the amount of data increases, and as the performance of exposure equipment and resists improves, the required exposure time decreases, and data from computers increases. The time required for transfer occupies a large proportion of the working time. The present invention aims to reduce the number of data transfers from a computer, thereby significantly shortening the working time.

In order to achieve such an object, the electron beam exposure apparatus of the present invention has the following features: ``When exposing a group of rectangular patterns of the same size and arranged in a matrix, one basic rectangular pattern constituting the pattern group is exposed. The position coordinates, pattern size, repetition pitch, and number of repetitions are stored in a register, and after one basic rectangular pattern is exposed, the contents of the position coordinate register are passed through an addition/subtraction circuit,
By adding or subtracting a pitch, the basic pattern is exposed at a position separated by the pitch, and by repeating this operation a predetermined number of times, the basic pattern is exposed in a matrix. For example, many parts of the exposure pattern of integrated circuits are composed of matrix-like arrays of small basic patterns, and in the case of large-capacity memories, in practice, such arrays block the memory area even within the chip. In the present invention, the data transferred from the computer is as shown in FIG. The number of repetitions X4,
Y, ~Y4 are given. A clock 30 determines the time required to expose one rectangular pattern. Therefore, in the case of the flying spot method, the termination pulse 44 shown in FIG. 2 is used as a clock. Assuming that the number of clocks input to this clock terminal is n, each time one pattern is written in the adder 31, the value of the repetition pitch X3 is cumulatively added to the position coordinate X of one corner of the basic pattern, and
, ten (n-1)X3 and sends it to output X. That is, X, gives the position coordinates of the corresponding corner of each pattern,
When one pattern is written, the corresponding position coordinates of the next pattern are given. At the same time, the counter 32 counts the number of clocks n, and the comparator 33 compares that value with the value of X4. When the two values match, writing of one column is completed. In the Y direction, the counter 34 counts the number of times m of matching signals are received by the same machine, and while comparing it with Y4 using the comparator 35, the adder 35 calculates the position coordinate Y of one corner of the basic pattern until the two values match. Add up the repetition pitch Y3 and get Y, ten (
m-1) Output Y3 as output Y. Assuming that X2 and Y2, which determine the size of one pattern, are the outputs X2 and Y2 as they are, this matrix array circuit can be used with the following exposure method, that is, the flying spot method shown in Figure 2, or the rectangular pattern shown in Figure 3. By connecting the input terminals X, , X2, Y, , Y2 of the control circuit in the exposure method, matrix array exposure becomes possible. It is.

According to the present invention, the time required to transfer data from a computer can be significantly reduced, and the length of working time, which is the biggest drawback in electron beam exposure, can be shortened.

Next, in the above matrix arrangement, it is possible to change the exposure point greatly from one pattern to the next.
For example, as shown in Figure 6a, after writing one column in the x direction, the Y direction shifts by one line, and the x direction returns to the initial basic pattern position, and the distance of the jump is almost as large as the chip size. There are many cases. Therefore, in analog operated circuits such as deflection circuits, unstable phenomena are likely to occur due to large jumps. For example, a multiplier requires some time to reach thermal equilibrium after undergoing a large voltage change.

Therefore, it is desirable to minimize jumps and always write and connect adjacent patterns separated by only one pitch, as shown in FIG. 6b, for example. To achieve this,
For example, after completing one row of exposure by adding the pitch to the contents of the register indicating the position coordinates in the x direction,
This is possible by adding the pitch to the contents of the register in the Y direction, moving to the next column, and then subtracting the pitch from the contents of the register in the x direction.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing how exposure pattern data is provided in an exposure apparatus using a conventional vector deflection method. FIG. 2 shows a block diagram of a scanning control section of a flying spot type deflection system. FIG. 3 shows a block diagram of a scanning control section of a deflection system using a rectangular pattern exposure method. FIG. 4 is a diagram showing how to provide exposure pattern data in the matrix array exposure method. FIG. 5 shows a block diagram of a control circuit that enables matrix array exposure. FIG. 6 shows the exposure order in matrix array exposure. 1 is a pattern,
2-5, 17-20, 37-42 Hashijista, 7, 12
, 32, 34 are force counters, 8, 13, 33, 35 are comparators, 9, 10, 14, 15, 21-24 are D-A converters, 11, 16, 25-28 are intensifiers. 6, 3 river clock, 29 is the basic pattern, 43, 44 are the end pulses.

Claims (1)

[Scope of Claims] 1. An electron gun that emits an electron beam, an electron lens system that focuses the electron beam, and a deflection system that deflects the electron beam to a desired position on a sample where an electron beam-sensitive resist is disposed. When a group of rectangular patterns having the same size and arranged in a matrix is subjected to electron beam exposure in an electron beam exposure apparatus having
The position coordinates of the basic rectangular pattern, the size of the pattern,
Store the repetition pitch and number of repetitions in a register,
After exposing one basic rectangular pattern, a pitch is added or subtracted from the contents of the position coordinate register through an addition/subtraction circuit, thereby deflecting the electron beam to a position separated by the pitch to expose the basic pattern, and this operation is performed in a predetermined manner. An electron beam exposure method characterized by exposing a basic pattern in a matrix by repeating it a number of times. 2. The electron beam exposure method according to claim 1, wherein there is no jump of two pitches or more in the exposure order of the basic pattern.