JPS6234137B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electron beam exposure apparatus, and more particularly to an electron beam exposure apparatus having an automatic divided exposure function using a variable rectangular beam, in which the fractional size to be exposed is divided into two shots at the final stage for processing. Related to exposure equipment. Conventionally, various types of electron beam exposure apparatuses have been proposed. The most orthodox one is the computer control method, which is currently widely used. To explain the system diagram of this method using Fig. 1, data input is performed by converting pattern data into binary data, and inputting a signal read from, for example, a magnetic tape by data input device 1, is input to a basic computer (CPU).
2, a storage device 2a such as a disk memory
Data is stored within. The predetermined data calculated within the basic computer 2 is added to the pattern drawing control device 3a, sample stage position control section 3b, etc. of the control section 3, and
The output of the pattern drawing control section 3a, that is, the beam deflection control signal, is converted into analog, amplified, and applied to the deflection electrodes 7c, 7d of the electron beam exposure device 7, and the beam cancellation signal from the pattern drawing control section 3a is also used for beam cancellation. Through the circuit 6, the beam erasing electrode (blanker) 7b of the electron beam exposure apparatus main body 7 is connected.
given to. Furthermore, the digital signal from the sample stage position control section 3b is also converted to analog and sent to the sample stage control and drive circuit 5.
A drive motor 8a for driving the sample stage 8 in the X-axis and Y-axis directions is controlled and driven through the sample table 8. In this manner, the sample 11 on the sample stage 8 is moved in the X-axis or Y-axis direction. Using such a computer-controlled electron beam exposure apparatus, the present applicant proposed a variable rectangular electron beam exposure apparatus 10 as shown in FIG. this is,
The electron beam 10k emitted from the electron gun 10a passes through the cathode slit 10b, the condenser lens 10c, and the first slit 10d.
The electron image of the slit 10d is formed on the second slit 10g via the lens 10f, and the electron beam 1
0k is such that the beam is deflected by a slit deflector 10e placed near the lens 10f, and the cross-sectional shape of the beam is made into a variable rectangle. In this way, when the electron beam passes through the second slit 10g, it becomes a rectangular electron beam 10k of the desired size,
The electron beam passes through the reduction lens 10h and the projection lens 10i, and the exposure position on the sample 13 is controlled by the main deflector 10j. When the pattern to be drawn is larger than the maximum beam size that can be set, a rectangle with the same size and shape as the rectangular beams 13a, 13b, 13c, and 13d is sequentially drawn in the X-axis direction from a predetermined position of the one-chip pattern 13 as shown in FIG. The final dimension in the X-axis direction is the same as that of the first and second slits 10.
The beam cross-sectional shape is controlled by the deflector 10e between d and 10g, and the rectangular beam 13e is exposed in accordance with the final size. Next, exposure in the Y-axis direction is performed using a rectangular beam 13f, and here the rectangular beam shape is expanded again to form rectangular beams 13g to 13j.
and are sequentially exposed. Of course, the scanning method is not limited to the scanning method described above. The problem in this case is that the dimensions of the final exposure beam 13e vary depending on the size of the chip pattern, but if they become extremely small, it becomes difficult to generate a stable electron beam. The reason for this is that as the size of the electron beam decreases, the exposure amount decreases due to blurring, and when the beam size is small, it is difficult to increase the electron beam current in proportion to the beam size. This is because the effects of drift, etc., are significant. The present invention proposes an electron beam exposure apparatus that eliminates the above-mentioned drawbacks, and is characterized by a variable rectangular beam exposure apparatus having an automatic pattern division exposure function, which can reduce the final fraction of the pattern size to 2 shots. The exposure is divided into two parts. Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 4 to 6. FIG. 4 shows a system diagram inside the pattern drawing control section 3 in FIG. 1 of the present invention, and the register 16 stores the pattern size of the horizontal dimension l of the sample 13 shown in FIG. . (Y
For simplicity, the axial direction will be omitted, and the explanation will proceed with only the X-axis direction. ) Also, the maximum beam size S is stored in the register 17, and the pattern starting point position _X0 in the X-axis direction shown in FIG. 5 is stored in the register 18. The output terminal of the register 16 is given to the subtracter 19 and the second gate circuit 26, and the output terminal of the register 17 is connected to the first gate circuit 22, the second gate circuit 26, and the multiplier 21. Furthermore, the output end of the register 18 is connected to the second adder 27, and the output end of the first gate circuit 22 is connected to the first adder 27.
The output end of the adder 24 is connected to the input of a latch circuit 25, and the output of the latch circuit 25 is fed back to the input end of the first adder 24 and the second adder 24 is connected to the input end of the adder 24. device 27 and subtractor 19
is input to the input terminal of. The output of the subtracter 19 is sent to the divider 20 and the comparator 23.
The output of the divider 20 is applied to a first gate circuit 22 and a second gate circuit 26. The output of the multiplier 21 is given to the other input terminal of the comparator 23, and the first and second gate circuits 22 and 26 are switched by the comparator output. Furthermore, the subtractor 19
The second gate circuit 26 is controlled by the other output of. The output from the second gate circuit 26 is passed through a beam size output register 28 and a digital-to-analog conversion circuit (not shown) to be amplified and driven into a slit deflector 10e shown in FIG.
is applied to form a rectangular electron beam of the desired size. Further, the output from the second adder 27 is also applied to the main deflector 10j via a beam position output register 29→digital-to-analog converter circuit, etc., for position control. In the above system diagram, dividers, multipliers, etc. are not specially provided with these circuits, and when the output of register 17 etc. is connected to the next register, the connection is shifted to the upper or lower digit in order and wired. Thus, the double product output or the quotient of 2 output can be easily taken out, so the connection may be made in this manner. The operation in the above configuration will be explained. First, the dimension l of sample 13 is l>S, for example 3S.
To explain the case of <l<4S, the exposure clock beam position output and beam size output are as shown in the table below.

[Table] Maximum beam size S of register 17 is multiplier 2
1 and added to the comparator 23, and the product value nS of the shot number taken out from the first adder 24 and latch circuit 25 and the maximum beam size is added to the subtracter 19. The output l−nS obtained by subtracting nS is given to the comparator 23. Therefore, the comparator 23 compares 2S and l-nS, and this output controls the first gate circuit 22. The output S of the S register 17 and the output (l-nS)/2 obtained by dividing the output l-nS of the subtracter 19 into two by a divider 20 are applied to the first gate circuit 22. Then, the output of the comparator 23 is 2S<
When the condition l-nS is satisfied, the first gate circuit 22 produces an output S, and the latch circuit 25 latches nS. Also, the output of the comparator 23 is 2S>
When the condition l-nS is satisfied, the first gate circuit 22 produces an output (l-nS)/2, and the latch circuit 25 latches nS+(l-nS)/2. Then, the adder 27 connects the output of the latch circuit 25 with
The pattern starting point position X from the X register 18 is added to generate a beam position output as shown in Table 1. Furthermore, the output of the comparator 23 is also applied to the second gate circuit 26, which performs the same control as the first gate circuit 22. That is, the second gate circuit 26
receives the output (l-nS)/2 of the divider 20 and the output S of the S register 17, and under the condition that the output of the divider 20 l>S, when 2S<l-nS, S, 2S> When l-nS, it produces an output of (l-nS)/2, and generates a beam size output as shown in Table 1. Therefore, according to the present invention, the first shot is shot with the electron beam 13a shown in FIG.
In step 3b, perform exposure with a rectangular beam of the same size, and in the next shot, reduce the rectangular beam size to 1-2S/2 and perform a shot.The final shot is also shot with the same rectangular beam size of 1-2S/2. Do what you want. In this way, the final shot will not be extremely small in size. In the above embodiment, only the X-axis was described, but it is clear that the same device can be used to perform the same operation in the Y-axis direction as well. In FIG. 5, the beam position is shown at the lower left of the sample 13 as indicated by a black dot 30, and the beam size is varied with the lower left point _X0 as a reference. Furthermore, when l<S as shown in FIG. 6, the exposure clock n=0 and the beam position output is X ₀ ,
The beam size output is set to l. That is, when the output of the subtracter 19 reaches a value of l<S in FIG. 4, the second gate circuit 26 is switched by the circuit shown by the dotted line to output the output of l as it is for exposure. Since the present invention is configured as described above, it is not necessary to expose the final shot with a small variable rectangular beam, and therefore stable exposure can be performed.

[Brief explanation of the drawing]

Figure 1 is a system diagram of a conventional computer-based electron beam exposure system, Figure 2 is an electron gun layout diagram of a conventional variable rectangular beam exposure system, and Figure 3 is a sample pattern showing a conventional variable rectangular beam exposure method. FIG. 4 is a plan view of the exposure shot above, FIG. 4 is a system diagram of the electron beam exposure apparatus of the present invention, FIG. 5 is a plan view of the exposure shot on a sample pattern showing the variable rectangular beam exposure method of the present invention, and FIG. 1 is a plan view of the exposure shot of the present invention when the sample pattern is smaller than the area of the exposure shot. 1...Data input unit, 2...Computer, 3...Control unit, 7, 10...Electron beam exposure device, 16,
17, 18...Register, 19...Subtractor, 20
...Divider, 21... Multiplier, 22, 26... Gate circuit, 23... Comparator, 25... Latch circuit, 24, 27... Adder.

Claims (1)

[Scope of Claims] 1. In a variable rectangular electron beam exposure apparatus having a function of automatically dividing a pattern to be exposed, the pattern size (l) to be exposed and the size obtained by sequentially dividing and exposing with a rectangular beam of a fixed size (S) (nS) at the edge of the pattern to be exposed;
nS)/2; and determining the magnitude of the difference dimension (l-nS) and twice the constant dimension (S) (2S), and when the difference dimension is smaller than 2S, exposure should be performed. An electron beam exposure apparatus comprising means for shooting a portion of a pattern corresponding to the differential dimension twice with a rectangular beam having a dimension obtained by dividing the pattern into two equal parts.