JP3623652B2 - Electron beam drawing method - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to an electron beam drawing method capable of drawing a mask material with high accuracy.
[0002]
[Prior art]
An electron beam lithography apparatus is used in the process of creating a mask for producing semiconductor devices. That is, an electron beam resist is applied to a mask dry plate, and a desired mask pattern is drawn on the material with an electron beam.
[0003]
When a mask is manufactured using this electron beam drawing apparatus, a mask blank as a drawing material is set in a holder in advance. This drawing holder is set in the preliminary exhaust chamber before drawing, and is loaded on the stage of the drawing chamber after evacuation.
[0004]
When the temperature of the loaded holder is different from the temperature of the stage, the position drift of the holder occurs, and the accuracy of the drawing position of the chip deteriorates. Usually, in order to avoid this problem, the temperature of the preliminary exhaust chamber is adjusted so that no temperature change occurs even if the holder is set on the stage.
[0005]
[Problems to be solved by the invention]
In recent years, mask drawing accuracy has become higher, and the adjustment of the above-mentioned temperature has also become a limit. For this reason, after loading the drawing holder on the stage, drawing is started after the temperature is stabilized.
[0006]
However, the problem with this method is that it is not possible to confirm whether the holder has stopped drifting. Secondly, in order to move the stage during drawing, if the position of the holder does not stop at a stable point, the holder may drift during drawing.
[0007]
As a countermeasure, it is necessary to increase the time required for temperature stabilization, that is, to set a waiting time for drawing for a certain time each time the stage is moved. End up.
[0008]
The present invention has been made in view of the above points, and an object thereof is to realize an electron beam writing method capable of drawing a mask pattern with high accuracy without reducing drawing throughput.
[0009]
[Means for Solving the Problems]
An electron beam drawing method according to the invention of claim 1 is a method of setting a drawing material on a holder and placing it on a moving stage, irradiating the drawing material with an electron beam deflected according to a pattern, In the electron beam writing method in which a desired pattern is drawn, a plurality of marks are provided on a holder or material, and each mark position is obtained by scanning the electron beam at the mark portion, and then again after a predetermined time has elapsed. The mark position is obtained, the drift amount of the holder or the material is obtained from both mark positions, and the pattern is drawn on the material if the drift amount is within an allowable value.
[0010]
According to the first aspect of the present invention, a plurality of marks are provided on the holder or the material, and each mark position is obtained by scanning the electron beam at the mark portion, and then the mark position is obtained again after a predetermined time has passed. Alternatively, a drift amount of the material is obtained, and if the drift amount is within an allowable value, a pattern is drawn on the material.
[0011]
According to a second aspect of the present invention, there is provided the electron beam writing method according to the first aspect of the invention, wherein the stage is moved or vibrated after the first mark position is obtained and before the next mark position is obtained.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of an electron beam drawing apparatus for carrying out the present invention. Reference numeral 1 denotes an electron gun for generating an electron beam EB. The electron beam EB generated from the electron gun 1 is focused on the mask dry plate 4 which is a drawing material by the condenser lens 2 and the objective lens 3. The electron beam is further deflected by the deflector 5, and a deflection signal corresponding to the pattern to be drawn is supplied from the deflection control unit 6 to the deflector 5.
[0013]
The mask dry plate 4 is set on a holder 7, and the holder 7 is placed on an XY moving stage 8, but the stage 8 is moved two-dimensionally by a stage driving unit 9. The amount of movement of the stage 8 is monitored by the laser length measuring device 10. The length measurement result of the laser length measuring instrument 10 is supplied to the computer 11.
[0014]
A pattern data memory 12 is connected to the computer 11, and the computer 11 reads the pattern data stored in the memory 12 and transfers this data to the deflection control unit 6. The computer 11 controls the stage drive unit 9 and performs various processes described later.
[0015]
Secondary or reflected electrons generated as a result of irradiating the mask dry plate 4 or the holder 7 with the electron beam EB are detected by the detector 13. The detection signal is supplied to the mark position detection unit 16 via the amplifier 14 and the AD converter 15. The mark position obtained by the mark position detection unit 16 is supplied to the computer 11.
[0016]
FIG. 2 is a plan view of the mask dry plate 4, the holder 7, and the stage 8. The holder 7 on which the mask dry plate 4 is set is placed on the stage 8. The stage 8 is provided with an L-shaped mirror 17 for measuring the amount of movement of the stage 8 by the laser length measuring device.
[0017]
Furthermore, the holder 7 is provided with cross-shaped marks M _{1 to} M _{4 at four} positions. The marks M _{1 to} M ₄ need to be provided far away from each other in order to accurately obtain the drift amount of the holder 7 described later. The operation of such a configuration will be described next.
[0018]
In a normal drawing operation on the mask dry plate 4, first, the mask dry plate 4 is set on the holder 7, and the holder 7 is loaded on the stage 8. Next, the computer 11 reads the pattern data from the pattern data memory 12, controls the stage drive unit 9 based on this data, and moves the stage 8 to a predetermined position.
[0019]
Thereafter, the pattern data is transferred to the deflection control unit 6, and a deflection signal based on the pattern data is supplied to the deflector 5. As a result, the electron beam EB generated from the electron gun 1 and focused by the condenser lens 2 and the objective lens 3 is deflected, and a desired pattern is drawn on the mask dry plate 4.
[0020]
Next, the stage drift handling operation as a previous stage of the above-described normal drawing operation will be described. First, the mask dry plate 4 is set in the holder 7, and the holder 7 is loaded on the stage 8. After the holder 7 is loaded on the stage 7, moves the stage 7 to scan the electron beam on the mark M ₁ provided in the holder 7, the detector secondary electrons or reflected electrons generated from the mark M ₁ part 13 to detect.
[0021]
The detection signal is supplied to the mark position detection unit 16 via the amplifier 14 and the AD converter 15, and the position of the mark M1 is detected. Similarly, the positions of the marks M _{2 to} M ₄ are detected, and the detection signals are supplied to the computer 11.
[0022]
In detecting the mark position, it is desirable to move the stage 8 so that each mark is arranged on the optical axis of the electron beam. In this case, each mark position can be obtained from the coordinate position of the stage measured by the laser length measuring device 10 and the mark position signal detected by the mark position detection unit 16.
[0023]
Computer 11, from the position signals of each mark _M 1 ~M _4, the shift amount from the ideal position of the holder 7 (Sx0, Sy0) and the rotation amount (Rx0, Ry0) and storing determined. Thereafter, the stage drive unit 9 is controlled by the computer 11, and the stage 8 is moved at the designated pitch and movement region. This movement is for adjusting the temperature of the stage 8 and the holder 7, and the stage 8 may be vibrated instead of the movement of the designated pitch and area.
[0024]
After the stage 8 is moved, the positions of the marks M _{1 to} M ₄ are detected again, and the shift amount (Sx1, Sy1) and the rotation amount (Rx1, Ry1) of the holder 7 are obtained. Then, both the shift and rotation drift amounts (ΔSx1, ΔSy1) and (ΔRx1, ΔRy1) of the holder are obtained. If the drift amount is within a preset allowable value, pattern drawing on the mask dry plate 4 is started.
[0025]
On the other hand, when both the drift amounts are equal to or larger than the allowable value, the stage 8 is moved again at the designated pitch and moving region, or the stage 8 is vibrated to thermally adapt the stage 8 and the holder 7. Perform the action. Then, the position of each mark is detected, and the shift amount (Sx2, Sy2) and the rotation amount (Rx2, Ry2) of the holder 7 are obtained.
[0026]
Based on the difference between the shift amount (Sx1, Sy1) of the holder 7 and the rotation amount (Rx1, Ry1) detected last time, both shift and rotation drift amounts (ΔSx2, ΔSy2), (ΔRx2, ΔRy2) of the holder 7 are obtained. Ask. If the drift amount is within a preset allowable value, pattern drawing on the mask dry plate 4 is started. Note that it is desirable that the allowable value be zero without a limit of position measurement accuracy for high drawing accuracy.
[0027]
The detection of each mark position and the drift amount described above is performed until the drift amount falls within the allowable value, but there is a limit on the number of drifts, and the drift is also measured by measuring the drift amount a predetermined number of times. If the amount does not fall within the allowable value, an alarm is given as an error, and subsequent pattern drawing is not performed.
[0028]
By automatically checking the drift amount before pattern drawing, the actual pattern drawing can be performed in a state where the drift amount can be ignored, and high-precision drawing can be realized.
[0029]
Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications are possible. For example, although four marks are provided, if there are a plurality of marks, the drift amount of the holder 7 can be obtained. In addition, the mark is provided on the holder, but when the mark is provided on the first layer on the mask blank as in the phase shift mask, the mark on the mask blank is used instead of the mark on the holder. The drift amount may be measured.
[0030]
Furthermore, after moving or oscillating the stage to make the holder and the stage conform, beam stabilization may be performed by performing electron beam dummy drawing or the like in a predetermined region on the holder or stage other than the material to be drawn. good. In that case, it is desirable to perform a drift check of the beam position or a beam current drift check by current measurement, and to use the drift amount based on this check as a correction factor when calculating the drift amount of the holder or the like. Furthermore, the present invention can also be applied to an electron beam lithography apparatus that changes the area of the electron beam irradiated onto the material.
[0031]
【The invention's effect】
As described above, in the first aspect of the present invention, a plurality of marks are provided on the holder or the material, each mark position is obtained by scanning the electron beam at the mark portion, and then the mark position is obtained again after a predetermined time has elapsed. The drift amount of the holder or material is obtained from both mark positions, and if the drift amount is within an allowable value, the pattern is drawn on the material.
[0032]
As a result, actual pattern writing can be executed in a state where the drift amount can be ignored, and high-precision mask writing can be realized. Also, compared to the conventional method in which drawing is waited for a set long time until the drift is stabilized, the present invention monitors the drift amount and immediately applies the drawing material to the drawing material when the drift amount falls within the allowable value. Since drawing can be performed, the drawing throughput can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of an electron beam drawing apparatus for carrying out the present invention.
FIG. 2 is a plan view of a stage, a holder, and a mask dry plate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electron gun 2 Condenser lens 3 Objective lens 4 Mask dry plate 5 Deflector 6 Deflection control unit 7 Holder 8 Moving stage 9 Stage drive unit 10 Laser length measuring device 11 Computer 12 Pan data memory 13 Detector 14 Amplifier 15 AD converter 16 Mark Position detection unit

Claims (2)

An electron beam set on a moving stage after placing a material to be drawn on a moving stage, and deflecting and irradiating the material to be drawn with an electron beam according to the pattern, thereby drawing a desired pattern on the material. In the drawing method, a plurality of marks are provided on a holder or material, and each mark position is obtained by scanning an electron beam at the mark portion. Thereafter, the mark position is obtained again after a predetermined time, and the holder or material is determined from both mark positions. An electron beam writing method in which a drift amount is obtained and a pattern is drawn on a material if the drift amount is within an allowable value. 2. The electron beam writing method according to claim 1, wherein the stage is moved or vibrated after obtaining the first mark position and before obtaining the next mark position.

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