JPH0586850B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a charged beam exposure method, and particularly to a charged beam exposure method that utilizes two types of deflection, large deflection and small deflection.

[Technical background of the invention and its problems] In the electron beam exposure method, the settling time of the DA converter for positioning the electron beam by deflecting it has a great effect on the throughput. In order to shorten the settling time, there is a method of performing main-sub two-stage deflection using a high-speed DA converter for main deflection that covers a large deflection area and a high-speed DA converter for sub-deflection that covers a small deflection area. This is a very effective method. This method has been described in the literature (EV, Weber
and RDMoore, J.Vac, Sci.Technol, 16,
1780 (1979)), it was put into practical use with the electron beam exposure system EL-2 (trade name). The effectiveness of this method has been demonstrated because most of the electron beam exposure devices using variable shaped beams that have been announced since the release of this device use this method.

However, this type of method has the following problems. That is, since the method is such that the sample stage is stopped and exposed, the throughput is low due to wasted time accompanying the movement of the sample stage. It is well known that the movement time of a sample stage during exposure in an electron beam exposure apparatus has a great effect on throughput. The method for performing exposure when the sample stage is stopped is as follows:
Since moving the sample stage from one exposure area to the next takes a lot of time, it is necessary to increase the deflection area and shorten the time for stepping and repeating the sample stage to improve throughput. It's summery.

However, in order to perform large deflections, it is difficult to improve pattern accuracy due to the effects of aberrations and distortions associated with deflection, and the current density of the electron beam decreases due to the large working distance during deflection. As a result, problems such as a decrease in throughput occur. On the other hand, when exposure is performed while the sample stage is moving, there is an advantage that the wasted time accompanying the movement of the sample stage can be significantly reduced compared to the step-and-repeat method.

These facts show that it is very advantageous to draw a pattern in two main and sub-stage deflections during continuous movement of the sample stage in improving the throughput of the electron beam exposure apparatus. However, in the method of exposing using two main and sub-stage deflections while the sample stage is continuously moving, when exposing a pattern in a small area using the sub-deflection, as the sample stage moves, the small A problem arises in that the pattern within the area is exposed, making it impossible to perform exposure.

Note that the above-mentioned problem also applies to ion beam exposure methods that use ion beams instead of electron beams.

[Purpose of the invention]

The present invention was made in consideration of the above circumstances, and
The purpose of this is to be able to draw a pattern at high speed by deflecting the main and sub-stages while the sample stage is continuously moving, and to draw the pattern and the area where the sub-deflection is possible as the sample stage moves. It is an object of the present invention to provide a charged beam exposure method that can correct the deviation in the positional relationship between the two and can improve the throughput.

[Summary of the invention]

The gist of the present invention is that during continuous movement of the sample stage, the main and sub
Due to the deflection of the stage, when performing pattern drawing, if the next pattern to be exposed deviates from the deflectable area of the sub-deflector during pattern exposure in the sub-deflection area, the deflectable area of the sub-deflector is This is corrected by the main deflector.

That is, the present invention uses a main deflector with a large beam deflection width and a sub-deflector with a small beam deflection width, and draws a desired pattern on the sample using a vector method while continuously moving a sample stage on which the sample is mounted. In the loaded beam exposure method, when the area to be exposed is divided into small areas that can be deflected by the sub-deflector and a pattern is sequentially drawn in each of the small areas, the movement of the sample stage during exposure of the small area causes the When the pattern in the small area is located outside the deflectable area of the sub-deflector, the exposure in the small area by the sub-deflector is interrupted, and the deflection position of the charged beam is changed by the main deflector so that the remaining pattern is In this method, after changing the pattern so that it falls within the deflectable area of the sub-deflector, the remaining interrupted pattern is drawn.

〔Effect of the invention〕

According to the present invention, even if the pattern to be drawn is located outside the sub-deflectionable area due to sample stage movement, the pattern is positioned within the sub-deflectionable area by correcting the beam deflection position using the main deflector. can be done. Therefore, there is no restriction on the moving speed of the sample stage during writing due to exceeding the sub-deflectable area of the writing pattern, and the throughput of the loaded beam exposure apparatus can be improved. In particular, for LSI patterns in which the number of drawn patterns varies greatly from sub-deflection area to sub-deflection area, the effect of improving throughput is tremendous.

[Embodiments of the invention]

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

FIG. 1 is a schematic diagram showing the structure of an electron beam exposure apparatus used in a method according to an embodiment of the present invention. 1 in the diagram
0 is a sample chamber, and within this sample chamber 10 is accommodated a sample stage 12 on which a sample 11 such as a semiconductor wafer is placed. The sample stage 12 is moved in the X direction (left/right direction in the paper) and Y direction (front/back direction in the paper) by a sample stage drive circuit 31 that receives a command from the computer 30. The moving position of the sample stage 12 is measured by a laser length measurement system 32, and the measurement information is sent to a computer 30 and a deflection control circuit 33, which will be described later.

On the other hand, above the sample chamber 10, an electron gun 21, various lenses 22a to 22e, various deflectors 23,
~, 26 and beam shaping aperture mask 27
An electron optical lens barrel 20 consisting of a, 27b, etc. is provided. Here, the deflector 23 turns on the beam.
- This is a deflection plate for blanking that turns OFF, and a blanking signal is applied to this deflection plate 23 from a blanking control circuit 34. The deflector 24 includes
This is a beam size variable deflection plate that variably controls the beam size using the optical aperture overlap of the aperture masks 27a and 27b, and a deflection signal is applied to this deflection plate 24 from the variable beam size control circuit 35. Ru. Further, the deflectors 25 and 26 are beam scanning deflection plates that scan the beam on the sample, and a deflection signal is applied to these deflection plates 25 and 26 from a deflection control circuit 33.

Here, the deflection plate 25 is a main deflection plate that largely deflects the beam on the sample, and the deflection plate 26 is a sub-deflection plate that deflects the beam small on the sample. and,
The beam position is determined by the main deflection plate 25, and the area within the deflectable area of the deflection plate 26 is drawn by the sub-deflection plate. The deflection control circuit 33 is configured to apply a deflection voltage to each of the deflection plates 25 and 26 via a high-speed DA converter.

Next, an electron beam exposure method using the exposure apparatus having the above configuration will be explained.

First, the basics of the exposure method in this embodiment is to divide the sample 11 into a plurality of frames (fields) 41 determined by the deflection width of the main deflection plate 25, as shown in FIG. Divide into 42 small areas (subfields) determined by the deflection width,
In this method, the position of the beam is set in a predetermined subfield using the main deflection plate 25, and the subfield is drawn using the sub-deflection plate 26. Furthermore, this is a method in which the sample stage 12 is continuously moved during this drawing.
In reality, while continuously moving the sample stage in one direction (Y direction), subfields of a predetermined field are
Sequential drawing is performed in the order of S ₁ → S ₂ → S ₃ → S ₄ → S ₅ → S ₆ → S ₇ → S ₈ → S ₉ .

In such an exposure method, for example, when subfield area _S5 is being drawn, the third
This will be explained in detail with reference to the figures. Further, the control flow of the computer 30 at this time is shown in FIG.

First, the main deflection position of the beam is set by the main deflection plate 25 at point _A1 as shown in FIG. 3a. At this time, the deflectable region R (the region surrounded by the broken line in the figure) of the sub-deflection plate 26 includes the entire sub-field _S5 . Next, patterns to be exposed P ₁ , P ₂ , ~
Draw P _N+J sequentially. At the end of drawing patterns P ₁ and P ₂ , the deflectable region R of the sub-deflection plate 26 is slightly shifted from the sub-field S ₅ due to the movement of the sample stage 12, as shown in FIG. 3B. However, since the patterns P _I , . . _. , P _N , .

However, if the number of patterns is large and the pattern drawing cannot follow the movement of the sample stage 12, for example, the third
When attempting to draw pattern P _N after drawing pattern P _I as shown in FIG. c, the pattern P _N to be drawn may be located outside the deflectable region R of the sub deflection plate 26. This was a factor that hindered drawing using the sample stage continuous movement method.

Therefore, in the method of this embodiment, when the situation as shown in FIG. 3c occurs, the main deflection position of the beam is reset from point _A1 to point _A2 using the main deflection plate 25, and the position as shown in FIG. The pattern P _N to be drawn is arranged to fall within the deflectable region R' of the sub deflection plate 26.
By doing this, the pattern P _N , ~,
It becomes possible to draw P _N+J . Therefore, the patterns P _N , . . . , P _N+J may be drawn in the order as before. Note that if the pattern to be drawn again leaves the deflectable area of the sub-deflection plate 26 during the drawing of the patterns P _N , ~, P _N+J , the main deflection position of the beam is changed by the main deflection plate 25 as before. Just reset it.

Thus, according to the method of this embodiment, a pattern can be drawn by deflecting the sample in two main and sub-stages while continuously moving the sample stage 12. Furthermore, if the patterns to be drawn are located outside the deflectable area of the sub-deflector 26 due to the movement of the sample stage 12, the beam deflection position is reset by the main deflector 25, so that these patterns can also be written in the same way. can be drawn on. In other words, the pattern of LSI etc. can be drawn effectively using the main and sub-stage two-stage deflection method using the sample stage continuous movement method. Therefore, compared to the conventional method of drawing a pattern by stopping the sample stage 12, the exposure throughput can be significantly improved.

In addition, in the method of this embodiment, the exposure order of the subfield patterns is defined in the same direction as the moving direction of the sample stage 12, so the position of the drawn pattern is changed as the deflectable area of the sub-deflection plate 16 moves. Therefore, the probability that the position of the pattern to be drawn will be outside the deflectable area is reduced. Therefore, the number of times the beam is reset by the main deflection plate 15 can be minimized, thereby further improving the exposure throughput.

Note that the present invention is not limited to the method of the embodiment described above. For example, the example of dividing the subfields within the field is not limited to the one shown in FIG. Just set it. Furthermore, it goes without saying that the exposure order of the subfields can also be changed as appropriate. Furthermore, the configuration of the exposure apparatus used in the method of the present invention is not limited to that shown in FIG. Any device may be used as long as it is equipped with a stage deflector. It is also possible to apply the present invention to an ion beam exposure method that uses an ion beam instead of an electron beam. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an electron beam exposure apparatus used in a method according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the relationship between fields and subfields, and FIGS. FIG. 4 is a schematic diagram for explaining the drawing procedure in the method of the embodiment, and is a flowchart showing the control flow of the computer during the above drawing. DESCRIPTION OF SYMBOLS 10...Sample chamber, 11...Sample, 12...Sample stand, 20...Electron optical column, 21...Electron gun, 2
2a, ~, 22e...Lens, 23...Blanking deflector, 24...Beam dimension variable deflector, 25...Beam scanning deflection plate (main deflector),
26... Beam scanning deflection plate (sub-deflector, 27
a, 27b...Aperture mask, 30...Computer, 31...Sample stage drive circuit, 32...Laser length measurement system, 33...Deflection control circuit, 34...Blanking control circuit, 35...Variable molding Beam size control circuit, 41...field, 42...subfield.

Claims (1)

[Claims] 1. Using a main deflector with a large beam deflection width and a sub-deflector with a small beam deflection width, a desired pattern is formed on the sample using a vector method while continuously moving the sample stage on which the sample is mounted. In a loaded beam exposure method for drawing, when an area to be exposed is divided into small areas that can be deflected by the sub-deflector and a pattern is sequentially drawn for each small area, the sample stage is moved during exposure of the small area. When the pattern in the small area is located outside the deflectable area of the sub-deflector, the sub-deflector stops exposing the small area, and the main deflector changes the deflection position of the loaded beam to the remaining pattern. A charged beam exposure method characterized in that after changing the pattern so that it falls within a deflectable region of the sub-deflector, the remaining interrupted pattern is drawn. 2. The loaded beam exposure method according to claim 1, wherein the exposure order of the patterns in the small area is set in the same direction as the moving direction of the sample stage.