JPS637631A - Electron beam drawing - Google Patents

Abstract

PURPOSE:To draw a circle, which has an arbitrary radius and has the center at an arbitrary point in a drawing allowance range of about 1 mm X 1 mm, by setting drawing regions at positions, which are separated from the center of the circle to be drawn by an equal distance, and controlling the gate opening time of a gate circuit so that central angles become constant. CONSTITUTION:An annular zone having the width of 1 mm or less is divided at an equal angle by radial lines, which are drawn from a center Oo of a circular pattern to be drawn. Then, the patterns to be drawn all become the same pattern. Therefore, a program for one pattern to be drawn can be used for many drawing regions. Each drawing region has rotary symmetry with the center Oo as the center. Therefore, when a substrate is rotated at every specified angle within an electron beam lithography apparatus, the drawing region is always set at the specified position. Thus operability becomes excellent. When two or more arcs are drawn in the drawing region, the gate opening time zone should be controlled so that the central angles of the arcs become equal.

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention Conventionally, signals V-V whose phases are shifted from each other by π/2 are used as signals for deflecting an electron beam.

According to the present invention, a DC signal ±VDc is superimposed on one of the above signals, and
The n:'r period in which these signals are applied to the deflection device is controlled by a gate device. With these two,
Traditional drawing tolerances (e.g. IllmXIIQI
ll), an arc with any radius and center at any point can be drawn. Moreover, the drawing area is set at a position equidistant from the center of the circle to be drawn by +1m, and the arc is drawn by controlling the gate opening time of the gate device so that the central angle is constant. A circular arc pattern that is rotationally symmetrical about the center can be drawn. Therefore, electron beam drawing of a circular pattern can be easily performed by sequentially drawing the same circular arc pattern on the circumference.

Background of the invention i-! TECHNICAL FIELD The present invention relates to a Lu-1 formula beam drawing method that is used as an effective patterning technique for the production of optical integrated circuits and other fine processing, and more particularly to a method for drawing circles or arcs.

BACKGROUND ART Electron beam lithography is a self-effective patterning technique for producing grating lenses and Fresnel lenses used in optical integrated circuits and the like. This is the first
As shown in the figure, an electron beam resist 3 is uniformly applied onto the U-plate 1. If necessary, a conductive wave film 2 (for example, indium tin oxide ITO-1n203+5nO2) is formed between the substrate 1 and the resist 3 for dissipating the charges accumulated on the resist. Ji,,fMl
A predetermined pattern (determined by the irradiation position and irradiation amount) is drawn on the top-etched electron beam resist 3 by the electron beam EB. Thereafter, a resist pattern having the above pattern is formed on the substrate 1 by developing the resist. The resist pattern on the substrate can be used as it is as a grating lens or Fresnel lens, or this resist pattern can be used as a mold or as a resist pattern.
It is also possible to plate the pattern and then remove the substrate and resist pattern to obtain a mold made of the plating material, and use these molds to mold the lens.

In any case, the patterning technology using electron beam writing takes advantage of the fact that the residual film rate of the resist after development depends on the amount of electron beam irradiation (either the area irradiated by the electron beam remains or it is not irradiated). Is there a part left?
It is characterized by determining the type of resist (positive or negative), the irradiation position of the electron beam, and (2) the predetermined pattern.

FIG. 2 shows an overview of a conventional electron beam lithography apparatus, and particularly shows an example of its electrical configuration. The electron beam emitted from the filament (see No. 71-9 in FIG. 4 described later), which is an electron beam emission source, is deflected by a deflection device 13.23, and is directed toward the substrate 1 coated with the above-mentioned electron beam J4/resist 3. The second image is scanned in a predetermined number of turns. Buttering requires control of the irradiation amount as well as the irradiation position, and the irradiation amount j! 'I . There are two types of deflection devices: one that deflects the electron beam by applying an electric field, and the other that deflects the electron beam using a magnetic field. The former type of deflection device includes a deflection plate for voltage application, and the latter type includes a deflection coil. In any case, a pair of deflection devices 1
3.23 act to impart mutually orthogonal forces to the electron beam traveling towards the substrate 1. As a result, in principle, the electron beam can be scanned in any direction within a two-dimensional plane. To simplify the explanation, it is assumed below that the former type of deflection device is used unless otherwise specified.

The trigonometric function wave generation circuits 11 and 21 have a mutual order Pa of π.
It generates trigonometric function wave signals shifted by /2, and each of these signals is expressed as V - V cos 0 cos ωt.

It is expressed as v −V, osjnωt (see Figure 3). These signals are each amplified by amplifier circuits 12.22 and then applied as voltage signals to deflection device 13.23.

Therefore, the electron beam receives a force in the direction opposite to the direction of the electric field generated by the applied voltage. -V. In the case of , as shown in Fig. 3, the electron beam has an internal angular velocity of ω in the XY plane. A circle with a radius corresponding to (-V, o) will be drawn.

In FIG. 2, a control device (CPU) 10 controls the above-mentioned trigonometric function wave generation circuits 11, 21, etc., and achieves drawing of a preprogrammed pattern by changing the angular frequency, amplitude, etc. of the signals.

Although in principle it should be possible to write any pattern with an electron beam as described above, there are various limitations in practice. For example, the maximum drawing range (drawing tolerance range) is 1
It is limited to a square of +nm x 1 mm, so 2
When drawing a circular pattern, only a circle with a maximum radius of 0.5 mm can be drawn (see FIG. 6).

The reason is as follows.

As shown in FIG. 4, when no deflection voltage is applied to the deflection device 13, 23, the electron beam EBI emitted from the filament 9 travels straight without being deflected, and the electron beam resist is coated. Irradiation is perpendicular to the center 0 (drawing origin, see FIG. 6) of the substrate 1. At this time, the electron beam EBI is focused on the substrate 1 to obtain a minimum spot diameter of 2γ.

When a voltage is applied to the EBI deflection device 13.23 to deflect the electron beam, the focusing point of the electron beam will draw a spherical surface as shown by F. As shown in an enlarged view in FIG. 5, the electron beam after passing the focusing point expands, so that the spot diameter of the deflected electron beam EB2 on the substrate 1 becomes BI 2γ which is larger than the above-mentioned 27 .

B2 Furthermore, in the undeflected electron beam EBI, the profile of the electron beam in a cross section perpendicular to the traveling direction of the electron beam EBI is circular, and the intensity distribution is also Gaussian type (Gaussian distribution). However, since the deflection electric field is applied to the deflected electron beam EB2, its cross-sectional profile is distorted 2 in the direction of the electric field.
The intensity distribution also deviates from the Gaussian shape.

In this way, the deflection of the electron beam increases the spot diameter on the substrate and deforms its cross-sectional profile and intensity distribution, so a deflection angle θ at which these effects can be almost ignored during writing is automatically determined. A drawing tolerance on the substrate is determined. This range is lH
This means that it is approximately X l mm.

As described above, in the conventional electron beam lithography apparatus, the maximum radius of a circle that can be drawn is only about 0.5 mm.

Moreover, there is a problem that the drawing is limited to a circle centered on the drawing origin.

Summary of the Invention Purpose of the Invention The present invention is an electronic device capable of drawing a circle or arc having an arbitrary radius and having its center at an arbitrary point within a drawing tolerance of about 1 mm x 1 mm as described above. The purpose is to provide a beam writing method.

Structure and Effects of the Invention The method of the present invention uses the following electron beam lithography apparatus. That is, in a device equipped with a pair of deflection devices that generate an electric field or a magnetic field that acts to deflect a rectilinear electron beam in directions orthogonal to each other in a plane substantially perpendicular to the direction of electron beam travel, the first F points are π to each other. A circuit that generates a trigonometric function wave signal shifted by /2 is provided for each of the pair of deflectors, and a DC signal generation circuit, an output of the trigonometric function wave signal of the trigonometric function wave signal generation circuit, and an output of the DC signal generation circuit are provided. The present invention is characterized in that at least one of the pair of deflection devices is provided with an addition circuit for superimposing a DC signal and a gate circuit for controlling a time period in which the output signal of the addition circuit is applied to the deflection device. An electron beam lithography system is used. The method of the present invention sets the drawing area at a position equidistant from the center of the circle to be drawn and within the drawing allowable range, and controls the gate opening time of the gate circuit so that the central angle is constant. By doing so, an arc is drawn within the drawing area.

When using the above electron beam lithography system, since the DC signal component is superimposed on the trigonometric function wave signal, the drawing origin on the drawing surface of the system can be moved by a distance corresponding to the magnitude of the DC signal component. It is possible to draw a circle whose center is at a position corresponding to the amount of movement and the radius corresponds to that, and since the drawing range of this circle can be controlled by a gate circuit, it is possible to draw only within the drawing surface of the device. As a result, it becomes possible to draw a part of the above-mentioned circle, that is, an arc, on the drawing surface. In other words, it is possible to draw an arc having an arbitrary radius and a center at an arbitrary point. Furthermore, the drawing area is set at a position equidistant from the center of the circle to be drawn, and the arc is drawn by controlling the gate open time period of the gate circuit so that the central angle is constant.

That is, since each cell obtained by dividing an annular band having the above-mentioned center into equal angles is used as a drawing area, a rotationally symmetrical arc pattern with respect to the above-mentioned center can be drawn. Therefore, if exactly the same circular arc pattern is sequentially drawn in the divided cells, electron beam drawing of a circular pattern of any size can be achieved. In addition, when molding and molding a lens with a circular pattern with a radius larger than the allowable drawing range using the method described above, it is possible to perform electron beam drawing of one cell as described above. It becomes possible to make a large number of molds with exactly the same pattern, and since such molds are rotationally symmetrical, if they are arranged in an annular pattern, the molds will have a circular pattern. In this way, even lenses with large circular patterns can be manufactured relatively easily.

DESCRIPTION OF THE EMBODIMENTS The electron beam lithography apparatus and its operation used in the embodiments of the present invention are shown in FIGS. 7 and 8. Figure 7 shows the electrical configuration of the electron beam lithography system (corresponding to Figure 2 showing the conventional example).
Components that are the same as those shown in the figures are given the same reference numerals.

Further, FIG. 8 shows the drawing operation of the circuit shown in FIG. 7 (corresponding to FIG. 3 which is a conventional operation explanatory diagram).

Referring to these drawings, particularly FIG. 7, the electron beam lithography apparatus includes a trigonometric function wave generation circuit 11. that generates a signal of V=Vxacosωt. The amplifier circuit 12, V
- Trigonometric function wave generation circuit 21 that generates a signal of Vyosinωt. The amplifier circuit 22. and deflection bag r! 113.
In addition to 23, the deflection device 13 is provided with a DC signal (for example, DC voltage) generation circuit 14, an adder circuit 15 for superimposing the output DC signal of the generator circuit 14 on the output trigonometric function wave signal of the amplifier circuit 12, and an adder. A gate circuit 16 is provided to control the time period in which the output signal of the circuit 15 is applied to the deflection device 13, and a DC signal generation circuit 24. An adder circuit 25 and a gate circuit 26 are provided. The angular frequencies ω of the output signals of the trigonometric function wave generation circuits 11 and 21 are individually variable and controlled by the CPU10 via the bus. The amplitude VV of these trigonometric function wave signals controls the amplification degree of the amplifier circuit 12.22.
O° yO can be changed by controlling the CPUl
Controlled by 0. Furthermore, the DC signal generation circuit 14
．． The magnitude of the DC signal generated from 24 (for example, voltage)
are also variable independently of each other and are controlled by CPU10, and the gate opening time periods of gate circuits 16 and 26 are generally set to the same time period, and are controlled by CPUI0.

Referring also to FIG. 8, trigonometric function wave generation circuits 11 and 21
The signals generated by the two are out of phase with each other by π/2. It is assumed that these signals have the same frequency ω and the same amplitude (VxO'' yO). It is assumed that the DC signal generation circuit 14 does not generate a DC signal (signal magnitude is zero), and the DC signal generation circuit 24 generates a DC signal having a value of -vDC. The output signal waveforms of adder circuits 15 and 25 in this case are shown in FIG.
.

It is indicated by Xa ■. Now, assuming that both the gate circuits 16 and Xa and 26 are open from time t to t2, the deflection device 23 receives a signal with a waveform of portions A1 to a B1 of the signal (2). is the signal V
A signal having a waveform of the A2-B2 portion is applied to Xa, respectively. As a result, the electron beam
It is scanned so as to draw a circular arc indicated by A o - B o within the drawing tolerance range of 1 mm.

This is because the DC component of -vDC is added to the Y-direction deflection signal, so the centers of the two circles are V on the Y-axis in the negative direction. Since a circle C8 is drawn by the signals V and V by moving by a distance corresponding to (center O8), Xa ya
This is because when the gates are opened from 1-1 to 1-12, the intermediate beam drawing is actually performed on the XY plane at angles .psi.-.omega.t to .omega.t2.

Change the amplitudes of the trigonometric function wave signals V and ■ to y V V respectively, and apply a direct current xi of −vDC to the signal V
'yl Y
By adding the components, we get the waveforms denoted by V and V x
C yc is done. Gate circuit 16.26 gate t-1-14
When opened between the two, electron beam drawing of nine circular arcs C6-Do can be achieved.

When a DC signal is superimposed on the trigonometric function wave signal V.

It becomes possible to move the heart in the X-axis direction within the circle.

As described above, electron beam lithography is performed by superimposing a DC component on at least one of the two trigonometric function wave signals and by gate-controlling the time for applying these trigonometric function wave signals to the deflection device. Within the drawing allowable range of the device (1 m+n×1 mm), it is possible to draw an arc whose radius is at least half (0.5 mm) of the length of one side of the drawing allowable range and whose center is at an arbitrary point.

When arcs with different radii are drawn, gate opening time period control corresponding to each arc may be performed.

Conventional devices could only draw patterns that were symmetrical with respect to the origin within the drawing tolerance, but with this device it is also possible to draw asymmetrical patterns.

Now, it is possible to draw a circular arc of any size as described above, but when drawing a concentric pattern on the board that is much larger than the drawing tolerance, as shown in Fig. 9, it is possible to draw a circular arc of any size. If we divide a 2U board into cells with the size of the allowable range P arranged vertically and horizontally, and draw each cell as a drawing area, each cell will have a different drawing pattern, so each drawing pattern can be drawn. The device must be programmed in advance, which is extremely complicated.

According to this invention, as shown in FIG. 10, an annular band having a width of III11 or less as shown by hatching is considered, and this annular band is drawn by a ray drawn from the center Oo of the circular pattern to be drawn. It is divided into equal angles, and each divided cell is defined as a drawing area R, R, etc. Each drawing region R, R, etc. is of course set to a shape that is smaller in area than the drawing allowable range P and falls within the range P. When such drawing areas R, R2, etc. are set, the drawing patterns in the drawing areas within the annular band indicated by the hatching (■) will all be the same pattern. Therefore, the above-mentioned problem is solved, and a program for one drawing pattern can be used for many drawing areas.

Moreover, since each writing area has rotational symmetry about the center 0°, if the substrate is rotated by a certain angle in the electron beam writing apparatus, the writing area is always set at a constant location, which provides good operability. When drawing two or more arcs in the drawing area, the central angles of these arcs should be equal.

It is necessary to control the gate opening time of the gate circuits 16 and 26. When molding or molding a lens or the like with a concentric pattern having a radius larger than the drawing tolerance range, it is sufficient to perform electron beam writing on only one writing area for the annular band mentioned above, and use this drawing pattern. This makes it possible to create a large number of split molds with the same pattern.

[Brief explanation of the drawing]

FIG. 1 is a perspective view for explaining a general electron beam lithography method. Figures 2 to 6 are for showing conventional examples. Figure 2 is a block diagram showing the electrical configuration, Figure 3 is a waveform diagram showing the drawing operation, and Figure 4 is a side view of the drawing process. An explanatory diagram from the perspective of
FIG. 5 is an enlarged view of a part of FIG. 4, and FIG. 6 is an explanatory diagram showing the drawing range and the maximum radius circle that can be drawn. 7 and 8 are for explaining the electron beam lithography system used in the present invention, and FIG. 7 is a block diagram showing its electrical tM configuration. FIG. 8 is a waveform diagram showing the drawing operation. FIG. 9 shows a general method of dividing a drawing area when drawing a circular pattern larger than the allowable drawing range, and FIG. 10 shows a dividing method according to the present invention. 11.21... Trigonometric function wave generation circuit. 12.22...Amplification circuit. 13.23...Deflection device. 14.24...DC signal generation circuit. 15.25...addition circuit. 16.26...Gate circuit. P... Drawing tolerance range. R1, R2...Drawing area. Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Kenji Ushiku (1 other person) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1

Claims (1)

[Scope of Claims] A pair of deflection devices that generate an electric field or a magnetic field that acts to deflect a rectilinear electron beam in directions orthogonal to each other in a plane substantially perpendicular to its traveling direction; A circuit for generating trigonometric function wave signals whose phases are shifted by π/2 from each other, and a DC signal generation circuit and a trigonometric function wave signal provided for at least one of the pair of deflection devices. An electron beam comprising: an adder circuit that superimposes the output DC signal of the DC signal generator circuit on the output trigonometric function wave signal of the signal generator circuit; and a gate circuit that controls the time period in which the output signal of the adder circuit is applied to the deflection device. Using a drawing device, a drawing area is set at a position equidistant from the center of the circle to be drawn, and an arc is drawn within the drawing area by controlling the gate opening time of the gate circuit so that the central angle is constant. To draw, electron beam drawing method.