JPS607380B2 - Electron beam exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electron beam exposure apparatus.

When exposed with an electron beam, it is possible to expose a small pattern, but the disadvantage is that the exposure time becomes long.

Various improvements have been made for this purpose, one of which is a method of exposing while moving the stage.

Another method is to use a rectangular beam for exposure instead of a spot-shaped electron beam.

The present inventors have developed an exposure apparatus that uses a rectangular electron beam to expose while moving the stage in order to increase the exposure speed as quickly as possible, but it is necessary to correct the deflection signal in order to move the stage. There is. To this end, we have previously proposed that the amount of movement of the stage be measured with a laser interference measuring device, input as a pulse signal to a counter, and then corrected by adding the output of the counter and the deflection signal with an adder.

However, since the densities of the patterns to be exposed differ, if you try to move the stage at a constant speed and correct the deflection signal by the amount of movement, in areas where the pattern density is large, the stage movement speed will be lower than the exposure speed. Since the movement of the light beam becomes slow, it is necessary to make a large deflection as the stage advances, and the accuracy of the exposed pattern deteriorates.

Further, in areas where the pattern density is low, the exposure speed becomes faster than the stage movement speed, and the stage is largely deflected in the direction opposite to the advancing direction, resulting in poor pattern accuracy. The purpose of the present invention is to eliminate such drawbacks, and the purpose is to use an electron beam that is shaped into a predetermined shape by a slit and exposes the object to exposure while moving the object. In a beam exposure device, a reference signal for moving the object to be exposed at a constant speed is modulated by a deflection signal passed through a smoothing circuit, so that areas with a high pattern density to be exposed are exposed to more light than areas with a lower pattern density. This is achieved by an electron beam exposure device characterized by slow body movement speed.

The present invention will be explained below based on examples. FIG. 1 is a diagram showing an embodiment of the present invention.

In the figure, 1 is a deflector, 2 is an object to be exposed, such as a wafer, 3 is a stage, 4 is a memory that stores pattern position information, 5,
8, 1 is a DA converter, 6 is a Caesar interference detector, 7 is a counter, 9, 12, 15 is an amplifier, 1 is a memory that stores a signal specifying the standard movement speed of stage 3, 13 is a differential dynamic amplifier, 14 is a DC servo motor, 1
6 is a smoothing capacitor. To explain the operation, a signal specifying the moving speed of the stage 3 from the memory 10 is converted into an analog signal by the DA converter 11 and inputted to the terminal of the differential amplifier 13 via the amplifier 12.

The DC servo motor 4 is located at the output from the differential amplifier 13.
Rotate to move stage 3. On the other hand, memory 4
The pattern position information is converted into an analog signal by a DA converter 5, amplified by an amplifier 9, and applied as a deflection signal to the deflector 1 to deflect a rectangular electron beam. Since the stage 3 is moving here, it is necessary to correct it.

For this purpose, a laser interference lengthening device is used to lengthen the moving distance of the stage 3.

That is, the laser interference side length device 6 outputs one pulse, for example, each time the stage 3 moves by 1/8 of the wavelength of the laser.

The pulses from the length transmitter 6 are counted by a counter, and the lower 4 bits are input to the DA converter 8.

The analog signal from DA converter 8 is applied to amplifier 9.

The output from the DA converter 5 and the output from the DA converter 8 are applied together to the amplifier 9, and correction is performed here.

Next, control of the moving speed of the stage 3 according to the pattern density will be described.

The signal applied to amplifier 9 is branched, amplified by amplifier 15, and applied to smoothing capacitor 6.

The time constant of the smoothing capacitor is set to about 20 to 5 tones of the deflection speed, and small density changes are ignored. A signal from smoothing capacitor 16 is applied to one terminal of differential amplifier 13. Here, the magnitude of the output from the smoothing capacitor 16 is determined by the ratio of the exposure speed and the moving speed of the stage 3.

That is, when the pattern density is high, the exposure speed becomes slower than the movement speed.

In this state, the output from the DA converter increases, so the deflection signal becomes a large positive voltage.

Therefore, the output of the smoothing capacitor becomes large. Furthermore, if the pattern density is low, the exposure speed will be faster than the movement speed. In this state, the output of the DA converter becomes small and the deflection signal becomes a negative voltage.

For this purpose, the signal from the smoothing capacitor 6 is input to one terminal of the rhombic amplifier 13, and the signal from the amplifier 12 is input to the ten terminal.
When the voltage applied to the motor 14 is lowered by subtracting between the signal from the amplifier 12 and the signal from the smoothing capacitor, and the moving speed is slow, addition is performed between the signal from the amplifier 12 and the signal from the smoothing capacitor. Increase the voltage to remove the battery.

As described above, according to the present invention, when the density of the pattern is high, the moving speed of the stage is slowed down, and when the density of the pattern is low, the moving speed of the stage is increased, thereby improving the accuracy of the pattern. can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, 1 is a deflector, 2 is a wafer, 3 is a stage, 4,1
0 is a memory, 5, 8, 11 is a DA converter, 6 is a Caesar interference converter, 7 is a counter, 9, 15, 12 is an amplifier 13 is an insert amplifier, and 14 is a DC servo motor. house diagram

Claims (1)

[Claims] 1. In an electron beam exposure apparatus that exposes an exposed object with an electron beam shaped into a predetermined shape using a slit while moving the exposed object, a reference signal for moving the exposed object at a constant speed. 1. An electron beam exposure apparatus characterized in that the moving speed of the exposed object is made slower in areas with a high pattern density to be exposed than in areas with a low pattern density by modulating this with a polarization signal passed through a smoothing circuit.