JPH022110A - Electronic beam exposure method - Google Patents

Abstract

PURPOSE:To make proximity effect correction process possible without causing a great increase in computer processing time by taking data in the boundary portion between data-converted pattern data group and connection pattern data group in pattern data group which connects between data-converted pattern data groups. CONSTITUTION:For a repetition pattern group 31, proximity effect correction process is performed on patterns except the outermost line (one row). At this time, nine repetition basic patterns are expanded, and proximity effect correction process is performed on the middle basic pattern 33. For a pattern having no repetition, data of the outermost two lines (two rows) is taken in from the repetition pattern group and expanded, and an ordinary proximity effect correction process is performed upto the outermost one line (one row) (the data 31b of the inner second line is used only to perform proximity effect correction process on the data 31a of the outermost first line). The pattern 31a of the outermost (connection portion between repetition pattern group and pattern having no repetition) of the repetition pattern group 31 is processed separate from the repetition portion 31, and therefore they are connected smoothly.

Description

[Detailed Description of the Invention] [Summary of the Invention] Regarding an electron beam exposure method, more specifically, proximity effect correction processing in an electron beam exposure apparatus, an increase in data amount and a computer processing time are required for pattern data having a group of repeated patterns. The purpose is to provide a method that allows proximity effect correction processing without significantly increasing the When converting data into a data format for electron beam exposure, for two pattern data groups that have a boundary, the pattern data at the boundary of one pattern data group is imported into another pattern data group and data conversion processing is performed. When creating new pattern data (C) by using the electron beam exposure method and arranging a plurality of pattern data groups (A+Az...An) that have already undergone data conversion processing, the pattern data group that has undergone data conversion processing Data at the boundary between the pattern data group (A1A2...An) that has undergone data conversion processing and the connection pattern data group (B) is imported into the pattern data group (B) that connects the data, and the data is converted. The method includes an electron beam exposure method for processing.

[Industrial application field]

The present invention relates to an electron beam exposure method, and more particularly to a proximity effect correction process in an electron beam exposure apparatus.

[Conventional technology]

In recent years, turnaround time (TAT) has been shortened, IC
As chips become more highly integrated and miniaturized, direct wafer exposure using an electron beam exposure apparatus has come to be used. When a sample substrate is irradiated with an electron beam, the influence of reflected electrons from the sample substrate is large, as shown in FIG. 6, and when patterns are close together, there is a problem that gaps cannot be resolved. Note that FIG. 6(a) is a plan view showing the position of the electron beam 11, and FIG. 6(b) is a cross-sectional view taken along line AA' in FIG. , and the electron beam intensity is plotted on the vertical axis. The area marked with sand in Figure 6 is the interference area 12, and this area is where the gap (G
) is not resolved.

Therefore, when exposing fine, highly integrated patterns to electron beams, it is essential to perform proximity effect correction.

Referring now to FIG. 4, an EB resist 22 (for example, a resist with the trade name PMMA) is coated on a silicon wafer 21 to a thickness of 1 μm. This wafer 21
When a single electron beam is irradiated with a single electron beam, which is shown by the solid line in Figure (b), the intensity of the incident electrons and the total irradiation amount is shown by lines 23 and 24, respectively, as shown in the cross-sectional view of Figure (a). The profile is shown, and the resist is exposed to light up to the range shown by line 24 (this range is shown by the broken line in FIG. 2(b)).

Note that in FIG. 2A, a line 25 indicates the range over which the scattered (reflected) electrons are effective.

FIG. 5 is a diagram showing a state when the beam shown in FIG. 4 is repeatedly irradiated, and shows a state in which a total irradiation amount 24 (indicated by a broken line in FIG. 5B) is obtained by repeating the incident electrons 23. Note that the profile shown in FIG. 5(a) is
This corresponds to each profile in FIG. 3(b), and the interference portion between them causes a problem as described above.

Conventionally, in an electron beam exposure apparatus, there are several methods for correcting the proximity effect, of which the following two methods are often used.

■ Increase the electron beam acceleration voltage to reduce the amount of reflected electrons from the sample substrate. Because the incident energy to the substrate is high, almost all of the electron beam penetrates into the sample substrate, and the amount of electrons that collide with sample substrate molecules and are reflected is small.

■ A computer is used to simulate the dose that is affected by the surrounding patterns at the sample point of each pattern (indicated by a in Figure 7), and the pattern dimensions are shifted so that the sample point receives the appropriate dose. For example, make a small change) and perform dose correction.

In addition, FIG. 7 is a diagram showing sample points and the range of the proximity effect.The range of the proximity effect of sample point a of pattern 1 reaches the range shown by the broken line A, and the pattern is 2', 2'',
2''' is affected by the proximity effect.

Method (2) has a limit in increasing the accelerating voltage (currently, the limit is about 50 KeV). Furthermore, since electrons pass through the resist when the accelerating voltage is increased, a large amount of irradiation must be applied to sufficiently expose the resist. Furthermore, it is difficult to design the electron optical system, the deflection voltage (or current) becomes high (large), and a high voltage (or large current) operating amplifier is required.

Although method (2) requires an enormous amount of computer processing time, it is possible to draw fine, high-precision patterns.

(Problem to be Solved by the Invention) When exposing a pattern with a large number of repetitions, such as a memory cell, to an electron beam, it is necessary to have repetitive pattern data (basic data), repetition pitch, and number of repetitions (repetition information). A method of developing the image (matrix exposure method, Japanese Patent Publication No. 60-6538) is effective.

When performing proximity effect correction processing on repeating pattern data, the amount of proximity effect changes depending on the circumstances of surrounding patterns, so it cannot be known unless a group of repeating patterns is developed. When a pattern is expanded, the amount of data increases, and the computer time required to correct the proximity effect becomes extremely large, which is impractical.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method that enables proximity effect correction processing to be performed on pattern data having a group of repeated patterns without increasing the amount of data or significantly increasing computer processing time. With the goal.

[Means to solve the problem]

The problem described above is that when performing electron beam exposure on pattern data consisting of multiple pattern data groups, when data is converted from design data to an electron beam exposure data format, a certain pattern data group is Electron beam exposure method that imports pattern data at the boundary part into another pattern data group and performs data conversion processing, and arranges multiple pattern data groups (^1^2...An) that have already undergone data conversion processing When creating new pattern data (C), the data conversion processed pattern data group (to 81) is added to the pattern data group (B) that connects the data conversion processed pattern data groups. This problem can be solved by an electron beam exposure method that takes in the data at the boundary with the connection pattern data group (B) of 2...^n) and performs data conversion processing.

[Operation] The problem described above can be solved by performing proximity effect correction processing on the pattern data group with repetition and the pattern data group without repetition separately, and then adding the two. However, since the conditions of the surrounding patterns are different at the connecting portion between a repeating pattern group and a non-repeating pattern group, the same proximity effect correction value as for the repeating pattern does not allow for smooth connection. Therefore, pattern data for two rows (two columns) from the repeating pattern group is expanded and incorporated into the non-repeating pattern group, and normal proximity effect correction processing is performed. By discarding the inner one row (column) of data and importing only the outermost row (column) of repeating pattern groups (connections) into the non-repetitive pattern group, we can create a repeating pattern group. , connections between non-repetitive patterns are connected smoothly.

In the present invention, as shown in FIG. 3(a), patterns in 2 rows and 2 columns on the outer periphery of the repeating pattern group 31 are developed and incorporated into the non-repeating pattern group 32.

Next, the proximity effect correction process is performed up to the outermost one row (one column). [The data in the second row (column) is the outermost row (1
Column) Used only to perform eye proximity effect correction processing. ] The outermost row (column) of the repeating pattern group is taken into the non-repeating pattern group and the repeating pattern group is individually subjected to proximity effect correction processing, and then added.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

Figure 2 shows data including a group of repeating patterns, 3
1 indicates a repeating pattern group, and 32 indicates a non-repeating pattern group.

Referring to FIG. 3(b), the repeated pattern group 31 performs proximity effect correction processing on patterns excluding the outermost one row (one column). At this time, nine repeating basic patterns with X=3 and Y=3 are developed and proximity effect correction processing is performed on the middle basic pattern 33 (number of repeats m−
1, n-1). For non-repetitive patterns, data for the two outermost rows (columns) of the repeating pattern group is taken and expanded, and normal proximity effect correction is performed for the outermost row (column) [inner two rows] The data 32b in the row (second column) is
It is used only to correct the data 31a in the first row (first column) of the outermost periphery]. According to this embodiment, the pattern 31a on the outermost periphery of the repeating pattern group 31 (the connecting portion between the repeating pattern group and the non-repeating pattern) is
This is a separate process, so it connects smoothly.

In the case of a composite chip, in which a new chip is created by combining pre-designed functional blocks such as memory, logic, or CPU, the data for each functional block is already determined, so there is no need to create new data. , simply place it on the chip. Figure 8 is a diagram of an example of a composite chip. In the figure, 83, A2, and A3 are already designed functional block data, and B is a data conversion-processed pattern data group (AI, A2..., An). Indicates a group of pattern data that connects the composite chip C=(AI+^2+...
・An) + B, and the part outside the broken line of the functional block data is the connection part (boundary part) where the proximity effect correction process is performed. As for the proximity effect correction processing, since the data in the functional blocks has already been designed, it is only necessary to newly perform the proximity effect correction processing on the connection portions with each functional block. In this case, the proximity effect correction process may be performed using the data before the proximity effect correction on the outermost periphery of each functional block.

FIG. 1 is a flowchart of an embodiment of the present invention. In implementing the method, first, the presence or absence of manipulation is checked, and if no, proximity effect correction is performed and the process ends.

Repeat part when there is repetition? For the repetition pattern group of Yes, the repetition number (X:n-L Y
See en-1) and remove pattern data expansion from X-3.
, Y=3), followed by proximity effect correction.

For patterns that do not repeat No in the repeating part, 2 rows (2 columns) of repeating patterns are taken in, 1 row (1 column) of repeating patterns is added to the non-repeating patterns, and proximity effect correction is performed. and the aforementioned proximity effect correction are added, and the execution of the method of the present invention ends.

〔Effect of the invention〕

As described above, according to the present invention, the repeating pattern group is
Since the pattern remains as a repeating pattern group, and the connections between the repeating pattern group and non-repeating patterns are connected smoothly, proximity effect correction processing can be performed without significantly increasing computer processing time or the number of pattern data. , it becomes possible to draw high-precision patterns.

[Brief explanation of the drawing]

Figure 1 is a flowchart of an embodiment of the present invention. Figure 2 is an explanatory diagram of a repeating pattern group and a non-repetitive pattern group. Figure 4 is a diagram of a group of patterns; (b) is a diagram of a group of repeated patterns; Figure 4 is a diagram of a single beam profile; (a)
is a cross-sectional view, (b) is a plan view, Fig. 5 is a diagram of multiple beam profiles, of which (a) is a cross-sectional view, (b) is a plan view, and Fig. 6 is a diagram explaining the proximity effect. (a) is a plan view, (g)) is a cross-sectional view taken along the line A-A' in (a), Fig. 7 is an explanatory diagram of the sample point and the range covered by the proximity effect, Fig. 8 is an example of a composite chip This is a diagram. In the figure, ■, 2', 2", 2#, 3', 3", 3" are patterns,
11 is an electron beam, 12 is an interference part, 21 is a silicon wafer, 22 is a resist, 23 is an incident electron, 24 is a total irradiation amount, 31 is a repeating pattern group, 31a is the outermost pattern of the repeating pattern group, 31
b indicates a pattern in the second row (column) inside the repeating pattern, and 32 indicates a pattern group without repeating.

Claims (3)

[Claims] (1) When pattern data consisting of multiple pattern data groups is subjected to electron beam exposure, when data is converted from design data to the data format for electron beam exposure, one pattern data group is An electron beam exposure method that imports pattern data at the boundary into another group of pattern data and performs data conversion processing. (2) The electron beam exposure method according to claim 1, wherein one of the two pattern data groups having a boundary portion is formed by repeating a plurality of basic data groups. (3) When creating new pattern data (C) by arranging multiple pattern data groups (A_1A_2...An) that have already undergone data conversion processing, the pattern data groups that have already undergone data conversion processing are Into the pattern data group (B) to be connected, data at the boundary between the data conversion-processed pattern data group (A_1A_2...An) and the connection pattern data group (B) is taken, and the data conversion process is performed. electron beam exposure method.