JPS5928980B2 - Electron beam exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pattern data storage, transfer, and control system in an electron beam exposure apparatus that enables high-speed exposure by varying the cross-sectional size of the electron beam.

Conventional fly fern spot electron beam exposure equipment exposes one point at a time using a narrowly focused electron beam, and in order to draw one pattern, it exposes several tens to hundreds of points with one pattern data provided. Although it is necessary to repeatedly expose each point, the disadvantage is that the exposure time becomes long.

For example, even if you expose one point at a time at 10 to 20 MHz,
An exposure time of about 30 minutes is required for each wafer having a diameter of 50 mm. Therefore, the present inventors previously proposed an electron beam exposure apparatus that can shape an electron beam into an arbitrary rectangular cross-sectional shape.

As shown in FIG. 1, this exposure apparatus includes electronic lenses 5 and 6.
After forming a parallel electron beam D into a rectangular shape using a first aperture T having a rectangular hole T', a rectangular electron beam image is formed by a deflector 8 and an electron lens 9 at a second aperture if)1.
0, and the rectangular hole 10 of the second diaphragm b10.
The size of the electron beam passing through the electron beam is controlled by a deflector 8. The electron beam thus shaped into a rectangular cross section of a predetermined size is irradiated onto a predetermined position on the wafer 14 by the deflector 12, and one pattern can be exposed at a time, which is 100 times more efficient than the fly fender spot method. The above exposure time can be shortened. In such an exposure apparatus, the time required to expose one pattern is approximately 1 to 0.1 microseconds. Although the exposure time itself can be greatly shortened by the electron beam exposure device as described above, when drawing an IC pattern containing a huge number of rectangular patterns, the pattern data cannot be transferred to a magnetic disk device or a magnetic drum as in the conventional fly fender spot method. In the method of storing data in the device, the time required for data transfer significantly impedes shortening the exposure time. As a specific example, if we consider drawing a C pattern that includes more than 10,000 rectangular patterns in a range of lwrm x 1 x 7E, 50T
wm×5077Z77! (There are 2,500 rectangular patterns on a wafer.) Using the above electron beam exposure apparatus, exposure can be completed within 25 seconds excluding data transfer time.

Considering the time required to transfer pattern data, first of all, when using an exposure apparatus such as the one described above, in order to draw one pattern, at least data (Xl, Yl) representing the size of the pattern and data representing the position of the pattern are required. Data (X2
, Y2). Usually each data X,,
X2, Yl, Y2, . . . are given as 14 to 16 bit digital information. IC chip is 57m x 5tm
250,000 rectangular patterns and includes 250,000 rectangular patterns. Since multiple such chips are arranged within the wafer, the total number of bits of pattern data is 250,000 x 16
Bit x 4 (=2M bytes) b1 This is stored in a magnetic disk device or the like. Approximately 100 such chips are arranged on the wafer, so the total number of data to be transferred is 200.
It is M bytes. That is, four types of 16-bit digital information must be transferred for all 25 million rectangular patterns on the wafer. On the other hand, since the average transfer rate from the magnetic disk device is, for example, 160 Kbytes/second, a total transfer time of 20 minutes or more is required.

As is clear from the above example, the data transfer time, which was not a problem in the conventional flying spot method because it was performed during the exposure of one pattern, has been improved by the electron beam exposure system capable of high-speed exposure as described above. In this case, it causes a fatal problem.

Therefore, the present invention provides a flexible control system that can perform high-speed pattern data transfer and that does not cause data transfer waiting time due to changes in the number of pattern data even when drawing various IC patterns. For the purpose of this, it has a plurality of shift register groups that store data representing the size of the pattern and data representing the position of the pattern in parallel, and each of the shift registers has its memory contents returned from its output end to its input end. The electronic device is characterized in that data stored in the shift register can be repeatedly read out, and a plurality of data for drawing one pattern can be transferred and drawn at a time by selecting a predetermined group from the group of shift registers. A beam exposure device is provided.

Further objects and features of the present invention will become apparent from the detailed description below.

First, to supplement the explanation of the exposure apparatus shown in Fig. 1, 1
, 2 and 3 are a cathode and a grid, respectively, which constitute an electron gun.
In the anode, 4 is a blanking deflector for temporarily stopping electron beam irradiation during unnecessary periods, and 11 and 13 are electron lenses for reducing the electron beam EB shaped into a desired rectangle and focusing it on the wafer 14. It is.

Although not shown, the deflectors 8 and 12 are each independently provided with X and Y deflectors. Figure 1 shows only the basic configuration, and it also includes an electron lens for correcting the rotation of the axis b of the electron beam EB, and an aperture b1 or aperture for shielding unnecessary components in the electron beam EB. Of course, deflectors for matching such as B7 and IO can be added as necessary. Data X representing the size (shape) of the pattern! , Y, are DA-converted and applied to the deflector 8, and data X, , representing the position of the pattern is
Y, is converted to DA and applied to the deflector 12, so that a rectangular electron beam of a predetermined size is irradiated onto a predetermined position of the wafer 14 coated with the electron beam resist, and one rectangular pattern is exposed once. It will be held in According to the present invention, a shift register capable of high-speed transfer is used as a storage device in which pattern data is to be stored.

In addition, in order to enable higher-speed data transfer, one shift register is provided corresponding to each bit of one type of pattern data (for example, Data is transferred in parallel at once. For example, 16 shift registers are provided corresponding to 16-bit pattern data X, and the configuration is such that 16-bit pattern data X1 is given at one time by outputs from these shift registers. Shift registers are similarly provided for other pattern data X2, Yl, Y2, etc., and by one shift of the shift register group configured in this way, one rectangular pattern can be drawn. It is configured so that all the pattern data required for the process is output at once. Many ICs on one wafer
Since the pattern to be drawn on each chip after the chips are formed is the same, the entire surface of the wafer can be exposed by repeatedly using pattern data corresponding to the pattern of one chip.

Therefore, each shift register in the above shift register group is configured to return the memory contents from its output terminal to the input terminal of the first stage of the shift register, so that the stored data can be circulated without being destroyed and read out repeatedly. will be made possible. This makes it possible to expose the entire wafer using a shift register with a smaller capacity.
According to the present invention, a plurality of shift register groups as described above are provided, and a predetermined shift register group is selected and pattern data is provided from that group.

As a result, even when IC patterns requiring different total numbers of pattern data are drawn, a flexible data control system that does not cause data transfer waiting time can be achieved. In other words, in the case where only one large shift register group is provided, if the total number of pattern data per chip is small compared to the capacity of the shift register group, a large number of patterns may be stored in each shift register. This results in empty bits, and the waiting time until the shifting of these empty bits is completed is wasted, leading to an increase in exposure time. On the other hand, if a plurality of shift register groups are provided as in the present invention, the waiting time can be completely eliminated by appropriately selecting a shift register group that can immediately output pattern data. The electron beam exposure apparatus of the present invention, which has been briefly described above, will now be described in detail with reference to the drawings.

FIG. 2 shows a schematic configuration of an electron beam exposure apparatus according to an embodiment of the present invention. In this figure, 20 is the same as the main body of the electron beam exposure apparatus explained in FIG. 1, and the same symbols as in FIG. 1 indicate the same parts. 100 is a data storage control unit, and 31, 32, 33, and 34 are shift register groups A, B, C, and D that store pattern data, respectively.

35 is a shift register group 31, 32 of A, B, C, Dl
, 33, 34 as appropriate and outputs the pattern data X, , Yl, X2, Y, which are output in parallel from the selected group, are transferred to the Xl register 41, Y, Y, respectively. Register 51, X2 register 61, Y,
It is input to register 71.

For example, each pattern data X,,Yl,X,,Y2 is 16
This 16-bit data is input to each register 41, 51, 61, 71 in parallel.

For example, 16-bit data is input in parallel to the X register 41, and is converted to a deflection voltage (or current) corresponding to the data X1 via the DA converter 42 and the amplifier 43. input to the deflector. The Y deflector of the deflection device 8 receives the data Y1 stored in the Y register 51 via the DA converter 52 and the amplifier 53.
It is input as a deflection voltage (or current) corresponding to 1. In this way, the deflection device 8 is given a voltage (or current) corresponding to the pattern data Xl, Yl representing the size of the pattern, and deflects the electron beam EB by a predetermined amount in the X and Y directions, thereby changing the cross-sectional shape of the electron beam EB. format into a specified rectangle.

The same goes for the pattern data X, Y, representing the position of the pattern, and the 1DA converters 62, 72 and the amplifier 63
, 73, a predetermined deflection voltage (or current) is applied to the deflection device 12 to irradiate the electron beam to the position corresponding to the pattern data X, ,Y. Each of the shift register groups 31, 32, 33, and 34 in FIG. 2 has a configuration as shown in FIG. 3, respectively.

This shift register group has the same number of shift registers as the number of pattern data bits required to draw one rectangular pattern. That is, pattern data X,,Yl
,
, 60, 70 are provided. The number of bits may be different for each pattern data, but usually each data is 14 to 14 bits.
It is 16 bits. The individual shift registers are connected from their output terminals 45, 55, 65, 75 to their input terminals 44, 5 as shown.
The memory contents are returned to 4, 64, and 74.
1. Therefore, when a shift pulse is input from the shift pulse input terminal 80 to each shift register, the data stored in the last stage of each shift register is returned to the first stage. In this way, the pattern data input to each shift register from the single input terminals 44, 54, 64, 74 circulates within each shift register without being destroyed. The outputs of each shift register are all input in parallel to the data selector 35, and therefore, all the data (4n1 bits) necessary to draw one rectangular pattern are input in parallel to the data selector by one shift. Since shift registers that can shift in 0.1 microseconds or less are easily available, pattern data can be transferred at a speed equivalent to or faster than pattern drawing.

The shift register group shown in Fig. 3 is as shown in Fig. 2.
Four groups, C and D, are provided and connected to the data selector 35 in parallel. ;2.(Next, the case where exposure is performed using the apparatus shown in FIG. 2 will be explained.

Generally, in an electron beam exposure apparatus, the area that can be exposed with aligned pits (hereinafter referred to as an exposure field) is not very large, and in order to expose the entire wafer, the stage on which the wafer is placed must be moved. The exposure field is usually small compared to LSI chips. FIG. 4a illustrates this state. In the figure, 81 represents one chip, and a shaded area 82 represents an exposure field. When drawing this LSI pattern using the exposure apparatus shown in FIG. 2, for convenience's sake, each chip 81 is divided into four areas A, B, C, and D, and the pattern data of each area is divided into four shift register groups 31. , 32, 33, and 34.

When area A is located within the exposure field 82 as shown in FIG.
is selected and the registers 41, Y2, Xl, Yl,
The pattern data is transferred to 51, 61, and 71, and the pattern of area A is drawn by the exposure apparatus main body 20. After the exposure of area A is completed, the wafer is moved so that area B is located within the exposure field 82 by moving the stage. Next, area B is exposed using the pattern data stored in the shift register group 32. At the end of exposure of area A, there is a possibility that the stage near the output end of the shift register group 31 will be an empty bit. This is because the number of pattern data required to expose area A is determined by appropriately dividing the chip pattern so as not to exceed the capacity of the shift register group 31. Therefore, after the exposure of area A is completed, a shift pulse is applied to each shift register in the shift register group 31 in parallel with the movement of the stage and the exposure of area B, and the data of the pattern to be drawn first when exposing area A is applied. When the shift registers circulate and reach the final stage of each shift register in the shift register group 31, the shift pulse application is stopped. Thereafter, when the exposure of areas B, C, and D is completed in the same manner, the exposure of one chip is completed.

Next, when the stage is moved and exposure of another chip is started, the pattern data stored in the shift register group 31 is ready to be outputted immediately. Therefore, exposure can be started immediately without waiting time for empty bit transfer. Furthermore, even when the total number of 0 pattern data for one chip is small, the waiting time can be eliminated at all.

For example, if the total number of pattern data for one chip can be stored in one shift register group, it is sufficient to store all the pattern data for one chip in each shift register group. If the capacity is less than 1/2, pattern data for multiple chips may be stored in one shift register group. In this way, even when exposing a pattern that requires only a small amount of pattern data, there is no waiting time due to empty pit transfer. The exposure procedure explained with reference to FIG. 4 is an example, and the size of each area after division is appropriately selected depending on the relationship between the number of rectangular patterns included therein and the capacity of the shift register group. Since there is no essential relationship with the size of the exposure field 82, the timing of stage movement, etc. is not limited to the above explanation.

In addition, the exposure order may be such that only a part of the area within one chip is exposed over the entire wafer, for example, A, B, A, B, . . . , C, D. ,C,
Of course, it is also possible to perform the exposure as D, . . . . Furthermore, to prevent loss of time due to stage movement,
Exposure may be performed while moving the stage at a constant speed. Regarding such an exposure method, the exposure apparatus according to the present invention is particularly effective since there is no waiting time for data transfer. Next, a case in which exposure as shown in FIG. 4 is performed using the apparatus shown in FIG. 2 will be described with reference to a more specific example.

It is assumed that the total number of rectangular patterns to be drawn on each chip 81 is 250,000. Therefore, the number of pattern data required to draw this is also 2 for each of Xl, Y, , X2, Y2.
There are 50,000 pieces. For convenience, one chip is divided into areas A, B, and C, each of which draws 64,000 rectangular patterns, and area D, which draws 58,000 rectangular patterns.

The pattern data Xl, Yl, X2, Y, each consists of 16 bits.0 shift register groups 31, 32,
Each shift register in 33 and 34 has a length of 80,000 stages, and each shift register group uses pattern data Xl, Y, , X2, Y, for drawing one rectangular pattern. There are enough numbers to output all of them in parallel, that is, 4×16=64. Pattern data groups for areas A, B, C, and D are stored in shift register groups 31, 32, 33, and 34, respectively. Therefore, each shift register is a shift register group 31, 3.
The shift register group 34 has 16,000 empty bits, and the shift register group 34 has 22,000 empty bits. Groups of shift registers 31, 32, 33, 3 used in the device shown in Fig. 2
4 and a specific configuration example of the data selector 35 part.
As shown in the figure.

In FIG. 5, 101 is a clock pulse generator and 110
Generate clock pulses at ~20MHz.

The generated clock pulses are A, B, and C shown in Figure 2.
, D shift register groups 31, 32, 33, 34, respectively. is applied to the deflector 4. Blanking amplifier 103 is AND gate 102
When the output of the deflector 4 is 0, a deflection voltage that blanks the electron beam is applied to the deflector 4. Initially, the flip-flop circuit 104 has an output of 0, and the other flip-flop circuits 105, 201, 301, . . .
・ is set to output 1. When a starting pulse is input to the flip-flop circuits 105, 201 from the terminals 106, 202, these flip-flop circuits 105, 20
1 is in the state of output 1, and a clock pulse is input to the counter 107 via the b1 AND gate 102.
Shift registers 211 and 2 through AND gate 203
12, . . . clock pulse is input. The shift register 211 stores the first bit of the pattern data X1, and the shift register 202 stores the second bit of the three-turn data X2.
Although it is omitted in the diagram, it accumulates feet.
A total of 64 shift registers are provided in group A, including the remaining 14 bits of pattern data X1 and 16 bits each of other pattern data Y1, X2, and Y. The same applies to the other groups B, C, and D. Therefore, from each shift register 211, 212, . . . of group A, 1
All bits of pattern data Xl, Yl, X2, Y2 necessary to draw one pattern for each clock pulse are output in parallel,
2,... are input.

On the other hand, the lower two bits of the counter 108 which counts the number of areas that have been exposed are outputted to the decoder 109. Initially, the output of the lower two bits of the counter 108 is 00, and only the output A of the decoder 109 is 1. Therefore, the output AND gates 221, 222, . . . of each group
, 321, 322, . . ., the outputs of the shift register groups 211, 212, . . . are output only from the AND gates 221, 222, . This output is OR gate 111, 112,...
are input to registers 121, 122, . . . via . This register 121, 122,...
is 1 each for pattern data Xl, Y, , X2, Y,
A total of 64 registers for 6 bits are provided, and correspond to registers 41, 51, 61, and 71 shown in FIG. In this way, one pattern data Xl, Yl, X, , Y, is transferred for each clock pulse, and the first
Until the deflection voltage (or current) corresponding to the pattern data is set in the deflectors 8 and 12 shown in FIG. Blanking is performed, and exposure is performed after setting is completed.

The counter 107 contains the number of clock pulses from the start of exposure,
Therefore, the number of exposed rectangular patterns is counted.

The number of pattern data stored in each group is stored in the group management shift register 130 and given to the register 131. This group management shift register 130 consists of a shift register group similar to that shown in FIG.
In addition to sequentially transferring the data to the memory card, the stored data can be circulated and read out repeatedly. Here, the group management register 131 is 64000, 64000, 64″000,
58000 is sequentially and repeatedly output as a binary code. The coincidence circuit 132 includes the counter 107 and register 1.
When the outputs of 31 and 31 match (in this case, when 64000 was counted), the flip-flop circuit 104 is given a power output to be in the O state, and the AND gate 102 stops supplying clock pulses to the counter 107 and turns on the electronic beam. Blanking.

At the same time, a shift pulse is applied to the group management shift register 130 to transfer the number of pattern data stored in group B to the register 131. Using this coincidence output as a stage start signal, the wafer is moved so that the exposure field 82 shown in FIG. 4 is located on area B. At this time, it goes without saying that the movement is performed using a highly accurate distance measuring means such as a laser interferometer so as not to cause positional deviation.
When the stage movement is completed, a stage stop signal is applied to the flip-flop circuit 104 to set it to 1 state, and is also input to the counter 108.

This cancels the blanking state, and since the counter 108 counts the number of exposed areas, its lower two bits become 01, and only the output B of the b1 decoder 109 becomes 1. This decoder output puts the flip-flop circuit 301 in the 1 state via the monostable multivibrator 307, and opens the AND gate 303.
0 is selected, and the shift register 311 in group B 300,
The 64-bit pattern data Xl, Yl, X2, Y2 stored in 312, . . . are outputted via AND gates 321, 322, . 112, . . . to registers 121, 122, . . . Here, regarding the A group 200, when 64,000 clock pulses are input, each shift register 211
, 212, . . . , the remaining b 16,000 empty bit strings reach the final stage. The number of clock pulses input to the shift register group in the A group is counted by the counter 204, and when it matches the register 205 that stores the number of stages of the shift register in the A group, the flip-flop circuit 201 is set to the O state by the matching circuit 206. , the output to the AND gate 203 is set to O, and the supply of clock pulses to the shift register group is stopped. Here register 205
80,000 is stored as a binary code, and as a result, the first bit of the 64,000 bits of data stored in each shift register 211, 212, . . . circulates and reaches the final stage. When this happens, the clock pulse supply is stopped. This transfer of empty bits (16,000 bits) continues even during stage movement or transfer of data stored in group B.

In this way, data is transferred from the shift register group in group B 300, and when the pattern data transfer of 64,000 is completed, the coincidence circuit 132 detects this and blanks the electron beam and issues a stage start signal.

Subsequently, in the B group 300, clock pulses are input to each shift register 311, 312, . When the leading bit reaches each shift register 311, 312, . Supply is stopped. Similarly, the data transfer from groups C and D ends and the A output of the b1 decoder 109 becomes 1 again.
1 is input to the AND gate 203 via the monostable multivibrator 207 and the flip-flop circuit 201,
A clock pulse is applied to each shift register 21 in group A 200.
1, 212, . . . , pattern data transfer is immediately started.

At this time, the upper bit of the counter 108 is counted by 1. This corresponds to completion of exposure for one chip. The register 133 stores the number of chips in one wafer, and when the exposure of all chips is completed, the counter 10
When a stage stop pulse is applied to the stage stop pulse 8, a coincidence output is generated from the coincidence circuit 134, the flip-flop circuit 105 is put into the 0 state, and the electron beam is blanked. This completes the exposure of the wafer. If the number of chips in one wafer is 100, the number of rectangular patterns to be exposed is 25 million, but the 64-bit pattern data required to draw one rectangular pattern is 1.
Since data is transferred at a speed of 0 to 20 MHz, pattern data for one wafer can be transferred in several tens of seconds, excluding the time for moving the stage.

Although omitted in the above explanation, the counters that provide outputs to each coincidence circuit are reset by the coincidence output, and the timing of electron beam blanking and exposure is adjusted by adapting the delay of the circuit. Of course, it is necessary to ensure that the

Note that although the above description has been made regarding the case where it is applied to the rectangular electron beam exposure apparatus shown in FIG. 1, the present invention is not limited to this, and it is necessary to transfer pattern data at high speed. Needless to say, it is effective when applied to all types of electron beam exposure equipment.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the configuration of an electron beam exposure apparatus main body to which the present invention is applied, FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a diagram illustrating a shift register group used in the embodiment of the present invention.
FIG. 4 is a diagram explaining the exposure procedure according to the embodiment of the present invention;
FIG. 5 is a diagram showing a data control system in an electron beam exposure apparatus according to an embodiment of the present invention. 7, 10... Diaphragm Bl8... Deflector for size control, 12... Deflector for position control, 31, 32, 33, 34... Shift register Group, 35... Data selector, 41, 51, 6
1, 71, 121, 122...Register, 81
... Chip, 82 ... Exposure field, 211, 212, 311, 312 ... Shift register.

Claims (1)

[Claims] 1. It has a plurality of shift register groups that store data representing the size of the pattern and data representing the position of the pattern in parallel, and each of the shift registers has the stored data returned from its output end to its input end. What is claimed is: 1. An electron beam exposure apparatus characterized in that a plurality of data for drawing one pattern are transferred at a time by selecting a predetermined group of the shift register groups and drawing the pattern.