JPS6188524A - Electron beam exposure apparatus - Google Patents

Abstract

PURPOSE:To realize drawing of fine pattern by measuring nonlinear distortion of deflection voltage waveform, calculating a distortion correcting value from this value, mixing a distortion correcting signal with a deflection signal having nonlinear distortion and forming a deflection signal having good linearity. CONSTITUTION:When a signal VS which attenuates a deflection signal VSout in synchronization with a synchronous signal Scnt rises linearly, the time until it becomes equal to the reference voltage Vref output from a computer 20 is measured. The distortion of waveform of deflection voltage VSout is measured 19 by measuring 23 a count time for each rise like a step from the minimum voltage VL to the maximum voltage VH. Based on this calculated value, the computer 20 reverses the polarity of reference value to generate a corrected value in proportional to a deviation. The computer 20 moreover stores 27 a corrected value using a digital value at the timing where the measuring time is divided into n-point, reads 28 such value through control with the synchronous signal Scnt and converts it into analog signal through the D/A converter in order to generate a corrected signal VSb. This signal is then mixed with a deflection signal VSa. Thereby, a deflection signal having good linearity can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electron beam exposure apparatus of an electron beam scanning type that deflects and scans an electron beam.

(Technical background of the invention and its problems) As a conventional electron beam exposure apparatus, for example, Japanese Patent Application Laid-open [115
Publication No. 753938 and Japanese Unexamined Patent Publication No. 57-83033 fl
There are some listed in l. Examples of the electron beam scanning method of the conventional electron beam exposure apparatus described in these are shown in the seventh section.
As shown in the figure.

As shown in Fig. 7, in this two-stage electron beam exposure, the table on which the sample is mounted is moved continuously in the Y direction at a constant speed, and the electron beam is applied to a square electron beam spot whose side is a. -1 is deflected and scanned in the X direction. The length of the table is the same as the size a of spot 1 of the electron beam △
Every time the electron beam moves by Y (in the Y direction), scanning of the electron beam in the X direction is repeated, sx , sx ,...
sx, and are exposed in this order. At this time, if the 0N10FF of the electron beam is controlled according to the figure data to be drawn, patterns 2 and 3 corresponding to the target figure will be exposed.

In Fig. 8, a synchronization signal H3 is used to start deflecting the electron beam in the X direction every time the table moves by ΔY in the Y direction.
and thereby a sawtooth voltage waveform for deflecting the electron beam spot 1 in the X direction, that is, an X deflection waveform ws
Then, the figure data shown in Fig. 7 is 0N10 of the electron beam.
Signals for controlling with FF (hereinafter referred to as blanking signals) sxcl, 5xc2.5xc3, 5xc4°5XC
The relationship with 5,5XC6 is shown. For example, in scanning with an Sx3 electron beam, the position and width of the pattern to be drawn are 1. 1. 11 of 13°t4. 'i is controlled between.

Generally, the area that can be exposed by one deflection scan of the electron beam in the X direction has a drawing width W of several tens of μm to several hundred μm, and the in-pan time tw thereof is several hundred nanoseconds to several nanoseconds.

FIG. 9 shows a deflection system of a conventional electron beam exposure apparatus.

Conventional electron beam exposure equipment does not have a method for correcting distortion of the deflection signal when it occurs inside the deflection signal generator 4 or the deflection signal amplifier 5, resulting in unevenness (spots) in the electron beam exposure.
It had the disadvantage of causing That is, in the conventional method, when the sawtooth deflection voltage waveform for deflecting the electron beam 7 is slightly distorted from a straight line and applied to the deflection electrode plate 6,
The speed of the scanning locus 8 of the electron beam 7 is no longer constant, resulting in uneven speed, and as a result, the drawn pattern is also distorted, making it impossible to obtain accurate dimensions.

This will be explained in more detail with reference to FIG. In Figure 9, VS
2 is an ideal linear deflection voltage waveform, which is shown as a solid line. VS2 is a deflection voltage waveform with non-linear distortion and is indicated by a dashed line. Ideal linear deflection voltage waveform V
At S1, the electron beam is deflected and scanned, and a blanking signal S
The pattern drawn when the 0N10FF is controlled by C is shown by a diagonally shaded area 9 on the lower left. On the other hand, the electron beam is deflected and scanned using the strain/υ linear deflection voltage waveform VS, and the pattern drawn using the same blanking signal sc becomes a diagonally shaded area 1o downward to the right. The latter pattern 1o has an error b−c in pattern width compared to the ideal previous pattern 9, and the pattern position is also shifted by d. As described above, the conventional electron beam exposure device has a problem in that it cannot correct the distortion caused in the deflection signal.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and is an electron beam that improves the viscosity of a drawn pattern by correcting the distortion of the deflection signal of the electron beam, which is the cause of deteriorating fI'im of the pattern. The purpose is to provide an exposure device.

[Summary of the invention]

In order to achieve the above object 1), the electron beam exposure apparatus according to the present invention measures the nonlinear distortion of the deflection voltage waveform, and
A distortion correction value is calculated from this value, and a distortion correction signal that cancels out this It is characterized by generating a deflection signal.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on an illustrated embodiment. FIG. 1 shows the head of an electron beam exposure device according to an embodiment of the present invention. A synchronizing signal S for controlling the start of deflection is input to the negative plane signal generator 11, the deflection distortion measuring device nt 19, and the distortion correction signal generator 17. The deflection signal generator 11 generates an nt sawtooth voltage waveform VSa in synchronization with the synchronization signal S 1 and inputs it to the mixer 12 . The distortion correction signal generator 17 generates a correction signal S signal VS of the same period in synchronization with the synchronization signal 5C1lt.
, the dog is input to the mixer 12. The mixer 12 generates the z signal vSo, which includes U, by combining these two cars a>'3 V S & V SB wo Ka, but this signal is passed to the next stage (- direction IS signal amplifier 13). This partial voltage waveform VS deflects the electron beam 15 passing between the deflection electrode plates ut 14. The surface of sample 13118 on the table (not shown) is scanned by scanning trajectory 1.
6 is drawn and exposed. At this time, the voltage waveform VSo applied to the deflection electrode plate 14. The deflection distortion measuring device 19 to which is input measures the distortion and inputs it to the total 13120.

Based on this input signal, the calculation section 20 outputs a signal for controlling the output VSb of the distortion correction signal generator 17.

Next, the operation of this electron beam exposure apparatus is shown in FIGS.
Explain using b). FIG. 2(a) shows a case where no distortion correction signal is output.

The output signal v s al of the in-pot double amount generator 11 has non-linear distortion with respect to the ideal linear waveform shown by the broken line.

Outputs a waveform (shown as a solid line). Distortion correction signal generator 17
If the output signal v s bi of
The output signal VS of 3 becomes distorted as shown in 1 in FIG. 2 ut1. In this embodiment, this distorted output signal 5out1 is input to the deflection distortion measuring device 19 to measure the nonlinear distortion, and this measured value is further calculated by the C
1tEi 20 is used to calculate the distortion correction setting 1 shift according to a predetermined relationship, and this calculated value is applied to the distortion correction signal generator 1.
Output to 7. Then, the distortion correction signal generator 17 generates an output signal v s b2 that cancels the distortion of the entire signal processing system as shown in FIG.
When mixed with a2, a deflection voltage waveform of 141J t2 with good linearity like the signal vS can be generated.

Next, the deflection strain measuring device 19, which is the main part of this electron beam exposure apparatus, will be explained in more detail with reference to FIGS. 3, 4, and 5.

Figure 3 shows one deflection strain measuring device. The oscillator 21 generates a pulse waveform Cc[K with a period of Δ, and the counting control circuit 22
Enter it. This pulse waveform C6, K (count a, ++
It passes through the S T A RT terminal input in the t2++ circuit 22 and is cut off by the S T Op terminal input, thereby becoming a count pulse waveform C1 and outputting it to the counting circuit 23 . On the other hand, the deflection signal vS is attenuated by an attenuator ut 24 to become a signal VS, which is input to one input terminal C1nA of the comparator 26. Comparator 2
The other input terminal C1nB of 6 is connected to the output V of the base t$ voltage generator 25, 8. is input.

Further, this reference voltage generator 25 receives the reference voltage setting value outputted from the metering device 20 as input. Counting control circuit 22
inputs the Domei signal 5cnt to the 5TART terminal, and
By inputting the output EQU of the comparator 26 to the T OP terminal, the count opening 9 (3
Since the count value of the count pulse C6 in the M1 number circuit 23 can be read by the count value of the count pulse C6 in the M1 number circuit 23, it is possible to read the count value of the count pulse C6 in the M1 number circuit 23. Since the period of - is constant as Δt, the counting time is shown as - It has a function of inputting S.nt and calculating 81 times.

Next, using FIG. 4, a method for obtaining the distortion correction signal by this time counting will be explained in detail. In FIG. 4, the deflection distortion measuring device 19 detects that the signal S, which is obtained by attenuating the deflection voltage waveform VSo, nt in synchronization with the synchronizing signal S, is at the highest potential V than the lowest potential V. When increasing the voltage linearly toward , measure the time T until reaching an arbitrarily set reference voltage . Each time the reference voltage Vref is increased stepwise from V to 1, the state of one-way distortion of the deflection voltage waveform can be determined by measuring the count time. Since the signal increases linearly from ■ to ■, it is shown as a solid line in the figure by the straight line p.S=1 and the deflection signal without G-plane distortion correction is shown as a broken line from ■ to Vll. As shown by the curve m shown in
Ru. Therefore, in the latter case, at time T, ■. Even if it becomes r, the potential difference ΔV will be different compared to the former case. This difference potential ΔV is given by the following equation.

Δv=V,. f---(V-V,)-r s
II Here, TS is the effective electron beam scanning time and the synchronization signal S. It shows the section of positive potential in the period of nt, and in this case, it shows the measurement time range. After all, this potential difference Δ■
is detected as a distortion component of the deflection signal.

Next, the operation of this deflection distortion measuring device 19 will be specifically explained. First, the calculation is performed by inputting a reference voltage setting value to the reference voltage generator 25 in advance from step 20, and specifying the reference voltage vref at the measurement point. Here, the reset signal RES is sent from the calculation hall 20.
ET, and the counting control circuit 22 and counting circuit 23 are reset by this reset signal RESET. Next, the counting control circuit 22 receives a count pulse n by the synchronization signal S.
It outputs tC and causes the counting circuit 23 to count. Although the count value of the counting circuit 23 increases with time ρ,
4's output Noburo VS also has the lowest potential■1. , and finally vS≧V. At this time, the coincidence signal EQU is output from the output terminal C88 of the comparator 26.
is output, the counting pulse C of the counting control circuit 22 is stopped, and the counting of the counting circuit 23 is completed]). By reading this count value, the troubleshooting machine 20 determines the same +
[
It is possible to know the time T until reaching . In other words, it can be determined by T-Δtx (count value). As mentioned above, the reference voltage V
How many times is specified between V and Vll, and each time ref
By measuring the count U between L and ``[-'', it is possible to know the numerator of the nonlinear distortion Δ■ of the deflection voltage 50111 within one hour TS.In this case, the generation of the oscillator 21 By making the period Δt of the pulse C65, sufficiently smaller than the measurement time TS, the time T for reaching the base voltage ■, .1 can be determined with sufficient viscosity.In addition, the base t!\voltage ■ , .f is the lowest potential ■, and the highest potential Vl
By setting a large number of values between l, it is possible to know the state of the distribution of the nonlinear distortion ΔV in more detail.

Next, the distortion correction signal generator 17 will be explained using FIG. 5. Here, the distortion correction signal generator 17 is connected to the memory 2
7, memory read control circuit 28, and D/A converter 29
It consists of Before the actual deflection by the electron beam, the calculation unit 20 calculates in advance the correction value to be given to the distortion correction signal unit 17 based on the measurement value measured by one deflection distortion measuring device, and writes it in the memory 27. . ;As a calculation method,
For example, the polarity from the reference value is reversed, and a value proportional to the deviation from the reference value is used as the correction value.As shown in FIG. Digital (correction, Dl,...) at points P, P1゜..., P on the time axis.

n OD, is used. Here, P i = -XTS (i=o, 1.-, n
).

Note that the time measurement was performed with respect to the reference voltage ref,
Point (7) on the time axis P i (i = o, 1, =・
, n) at digital value [)i (i=o, 1...
・, n) is the reference voltage ■,. , can be determined by setting sufficiently thin and large numbers of .

As described above, according to this embodiment)! Although time was measured by applying voltage vref and nonlinear distortion of the deflection signal was measured, conversely, time point P1 (i=o, 1..., n
) by measuring the voltage (true) of the deflection signal using an A/D converter, a digital value Di for direct correction (i=
o, 1. ..., n).

〔Effect of the invention〕

As described above, according to the present invention, by adding the function of roughness correction, highly accurate deflection with less nonlinear distortion can be obtained, and the pattern drawing rate can be improved. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an electron beam exposure apparatus according to an embodiment of the present invention, FIGS. 2(a) and 2(b) are time charts showing each input/output signal waveform of the electron beam exposure apparatus, and FIG. 3 is the same. A block diagram of one deflection distortion measuring device in the electron beam exposure apparatus. FIG. 4 is a time chart showing the operation of the deflection distortion measuring device 19. FIG. 5 is a block diagram of one distortion correction signal generator in the electron beam exposure apparatus. , FIG. 6 is a time chart explaining the operation of the distortion correction signal generator 19, FIG. 7 is a diagram showing the electron beam scanning method of a conventional electron beam exposure apparatus, and FIG. 8 is a diagram showing the electron beam scanning method of the conventional electron beam exposure apparatus. Sync signal H at J3
8, Xgl direction waveform W S, blanking signal 5xc1,
5xc2. . . , a time chart showing 5XC6, FIG. 9 is a block diagram of a conventional electron beam exposure apparatus, and FIG. 10 is a diagram showing the relationship between deflection voltage waveform drawing patterns of the electron beam exposure apparatus. DESCRIPTION OF SYMBOLS 1... Spot of electron beam, 2.3... Exposure pattern corresponding to the figure to be drawn, 4... Deflection signal generator, 5... Deflection signal amplifier, 6... Deflection electrode plate, 7
...electron beam, 8...electron beam scanning trajectory, 9
...Pattern drawn with distortion-free deflection voltage waveform,
DESCRIPTION OF SYMBOLS 10... Pattern drawn with distorted deflection voltage waveform, 11... Deflection signal generator, 12... Mixer, 1
3... Deflection signal amplifier, 14... Deflection electrode plate, 15
...electron beam, 16...electron beam scanning trajectory,
17... Distortion correction signal generator, 18... Sample, 19.
... Deflection distortion measuring device, 20... Calculation, 21... Shooting device, 22... Counting control circuit, 23... Counting circuit, 2
4... Attenuator, 25... Reference voltage generator, 26...
- Comparator, 27...Memory, 28...Memory read control circuit, 29...D/A converter. Figure 7 Figure 9 Figure 10 - Ginma

Claims (1)

[Scope of Claims] 1. In an electron beam exposure apparatus that draws a fine pattern on a sample by deflection scanning an electron beam, a deflection distortion measuring means for measuring deflection distortion of a deflection scanning signal for deflection scanning the electron beam; , distortion correction signal generating means for generating a distortion correction signal for correcting the deflection distortion based on the deflection distortion measuring means, and correcting the deflection scanning signal with the distortion correction signal generated from the distortion correction signal generation means. An electron beam exposure apparatus characterized by comprising a distortion correction means. 2. In the device according to claim 1, the deflection distortion measuring means includes a reference signal generating means for generating a reference deflection scanning signal, and a reference deflection scanning signal generated from the reference signal generating means and the deflection distortion measuring means. and a calculation means for comparing the scanning signals and calculating the difference at each point in time of these signals,
An electron beam exposure apparatus characterized by measuring deflection distortion from this difference.