JPH1154396A - Electron beam drawing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to prevent unwanted exposure with a leakage beam and realize improvement in the reliability of a pattern. SOLUTION: This device has a beam-shaping mechanism (18, 19, 20) for shaping a beam emitted from an electron gun 17 into a predetermined shape, deflectors 23, 24 for scanning a sample with the shaped beam, a blanking mechanism (21, 22) for blanking the beam on a side closer to the sample than the beam shaping mechanism, a stage controller 27 for moving a stage 25 on which the sample is set, and a least interferometer 26 for detecting the moving speed of the stage 25. This device draws a pattern with a variable shaped beam, while continuously moving the stage 25. In this case, under the condition that the beam is being blanked by the blanking mechanism and when stop of the stage 25 is detected by the laser interferometer 26, the beam size is practically controlled to 0 by the beam-shaping mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam lithography system of a continuous stage moving type using a variable shaped beam, and more particularly to an electron beam lithography system which takes measures against a leakage beam when the beam is off.

[0002]

2. Description of the Related Art In recent years, finer patterns and higher densities have been promoted in order to increase the scale of semiconductor integrated circuits, but electron beam lithography systems have been used to generate high-density patterns. In the electron beam writing apparatus, a so-called variable shaped beam writing method is mainly used to improve the processing speed. In this method, the throughput can be improved by shaping the electron beam into a rectangular or triangular shape using a plurality of shaping apertures and exposing the pattern data in a certain area collectively.

FIG. 5 shows a conventional variable shaped beam type electron beam writing apparatus. This apparatus includes a control computer 11, a data expansion circuit 12, a deflection control circuit 13, a shaping deflection amplifier 14, a main deflection amplifier 15, a sub deflection amplifier 16, and an electron gun 1.
7, the first forming aperture 18, the forming deflection electrode 19, the second
Molding aperture 20, blanking electrode 21, blanking aperture 22, main deflection electrode 23, sub deflection electrode 2
4, a sample stage 25, a laser interferometer 26 for measuring a stage position, and a stage controller 27.

The computer 11 stores pattern data in a compressed format. The compressed pattern data is transferred from the computer 11 to the data expansion circuit 12. The data expanding circuit 12 converts the data into shot, sub-deflection position, and main deflection position data by expanding the data.
The data is transferred to the deflection control circuit 13. The deflection control circuit 13 sets a voltage in the main deflection amplifier 15 based on the stage position and the main deflection data obtained from the laser interferometer 26, and thereby sets the position of the main deflection. Then, after the origin of the sub deflection field is set by the main deflection, voltages are successively set to the sub deflection amplifier 16 by the sub deflection data, and a basic figure group in the sub deflection field is drawn.

The electron beam generated from the electron gun 17 is
It is formed into a rectangle by the forming aperture 18. The shaped beam images the image of the first shaping aperture 18 onto the second shaping aperture 20. At this time, the shaping deflector 19 causes the second shaping aperture 2 according to the voltage of the shaping deflection amplifier
By changing the beam position above zero, a shaped beam of desired dimensions can be delivered to the objective lens.

In a normal state, the beam is cut by a blanking aperture 22 by applying a voltage to a blanking electrode 21. After each figure is formed into a basic figure in the beam forming unit, the application of the voltage to the blanking electrode 21 is stopped to change to a beam irradiation state. After the necessary irradiation time has elapsed, the beam is cut again by applying a blanking voltage. As described above, in a normal writing state, beam cutting and beam irradiation are alternately repeated.

In the drawing by the continuous stage movement method, a drawing pattern is divided into several strip-shaped areas called stripes, and each area is continuously drawn while moving the stage. After drawing all the data in the continuous drawing area, the beam is cut and preparation for drawing the next area is performed in that state, and the stage is moved to the start position of the next drawing area and waits. By repeating such an operation until all the strip regions are drawn, a target pattern is drawn.

However, this type of system has the following problems. That is, in the case of drawing by the continuous stage movement method, there is a moment when the stage stops during a standby time from the end of drawing of each strip region (hereinafter referred to as a stripe) to the start of the next stripe drawing. In that case, the imaging position of the forming aperture also stops. In a normal blanking mechanism, the beam attenuation rate is about 1 × 10 ⁻⁶ . This level of decay rate is sufficient for continuous movement, but if the stage stop time lasts about 1 second, the leaked beam exposes the sample, which becomes a pattern defect and poses a problem.

In order to solve this problem, a method has been devised in which the end signal of the writing of each stripe is detected and the beam shaping unit is set so that the beam size becomes substantially 0 (Japanese Patent Publication No. Hei 5 (1993)). -87014). However, even with this method, a leak beam as described below poses a problem.

In the normal stage continuous movement drawing, the continuous movement drawing is performed at such a speed that overflow does not occur by estimating the stage movement speed from the pattern density.
However, if the predicted speed becomes higher than the actual speed, an overflow occurs. In this case, drawing must be interrupted, the stage must be returned to the interrupted position, and the stage speed must be reduced to restart drawing. At this time, there is also a moment when the stage stops. In this case, since the above-described drawing end signal is not generated, exposure by a leak beam becomes a problem. In addition, it is conceivable that the stage stops for a certain period of time for some reason. Again, a similar problem can occur.

[0011]

As described above, in the conventional stage continuous movement type electron beam writing apparatus,
Unnecessary exposure occurred due to the influence of the leakage beam when the stage was stopped, and this was a factor that reduced the reliability of the pattern.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent an unnecessary exposure by a leak beam and to improve an electron beam which can improve the reliability of a pattern. An object of the present invention is to provide a drawing device.

[0013]

[Means for Solving the Problems]

(Structure) In order to solve the above problem, the present invention employs the following structure. That is, the present invention is an electron beam drawing apparatus that draws a pattern with a variable shaped beam while continuously moving a stage, and a beam shaping unit that shapes a beam emitted from an electron gun into a predetermined shape, and a beam shaping unit that shapes the beam. Beam scanning means for scanning on the sample surface, blanking means for blanking a beam on the electron gun side or on the sample side than the beam shaping means, stage driving means for moving a stage on which the sample is mounted, and Monitoring means for monitoring the moving speed of the stage, and an interrupt signal generating circuit for generating an interrupt signal when it is determined that the moving speed of the stage satisfies a predetermined condition. It is characterized by the following.

The present invention is also an electron beam writing apparatus for writing a pattern with a variable shaping beam while continuously moving a stage, comprising: a beam shaping means for shaping a beam emitted from an electron gun into a predetermined shape; Beam scanning means for scanning the beam on the sample surface, blanking means for blanking the beam on the electron gun side or on the sample side with respect to the beam shaping means, and stage driving means for moving the stage on which the sample is mounted And an interrupt signal generating circuit for generating an interrupt signal when a stop instruction is issued to the stage by the stage driving means and the next movement instruction is not issued within a preset time when the instruction is completed. It is characterized by comprising.

Here, preferred embodiments of the present invention include the following. (1) The interrupt signal generation circuit shall detect the stop of the stage and generate an interrupt signal.

(2) Controlling the size of the shaped beam to substantially zero by the beam shaping means in response to the interrupt signal from the interrupt signal generating circuit. (3) Blanking a beam at a higher voltage than normal blanking by blanking means in response to an interrupt signal from an interrupt signal generating circuit.

(Operation) According to the present invention, the state of the stage is constantly monitored, and when the state satisfies a certain set condition, an interrupt signal is generated, and the beam size is controlled to substantially 0 by the interrupt signal. Alternatively, the beam can be reliably cut by blanking the beam with a higher voltage than normal blanking. Therefore,
Unnecessary exposure due to the leakage beam can be prevented, and the reliability of the pattern can be improved.

[0018]

Embodiment

(First Embodiment) FIG. 1 is a schematic configuration diagram showing an electron beam writing apparatus according to a first embodiment of the present invention. In the figure, 11 is a control computer for performing various controls, 12 is a data expansion circuit for expanding compressed data, 13 is a deflection control circuit for controlling various deflectors, 14 is a shaping deflection amplifier, and 15 is a main part. Deflection amplifier, 16 is a sub deflection amplifier, 1
7 is an electron gun, 18 is a first shaping aperture for beam shaping, 19 is a shaping deflection electrode, 20 is a second shaping aperture for beam shaping, 21 is a blanking electrode, 22 is a blanking aperture, and 23 is a main deflection electrode. , 24 are sub-deflection electrodes, 25 is a sample stage, 26 is a laser interferometer for measuring the stage position, 27 is a stage controller,
The basic configuration and the basic operation of drawing up to this point are the same as those of the conventional apparatus.

In addition, in the present embodiment, the moving speed of the stage 25 can be read by the stage speed monitoring circuit 28 from the laser interferometer 26 for measuring the stage position. The stage speed monitoring circuit 28 is provided for the stage 2
5 is constantly monitored, and an interrupt signal is sent to the computer 11 when the speed falls below a certain value.

When the computer 11 detects that the stage speed has become equal to or less than a predetermined value, it sends a signal for setting the beam size to 0 to the shaping deflector 19 through the deflection control circuit 13 and the shaping deflection amplifier 14. Then, the light is deflected until the image of the first shaping aperture 18 is formed outside the second shaping aperture 20.

In this state, since the image of the first shaping aperture 18 does not illuminate the opening of the second shaping aperture 20, the leakage of the beam is very small as compared with the normal state, and the amount of the leak beam is small. Less. Therefore, unnecessary exposure due to the leak beam can be prevented even when the stage is stopped.

It should be noted that the beam is blanked by the blanking mechanism except at the time of writing, and the beam is blanked even when the stage speed falls below a certain value, for example, when the stage 25 is stopped. It has become. However, since the beam attenuation rate by the blanking mechanism is not completely zero, slight leakage occurs. In the present embodiment, the leak beam can be further reduced by controlling the size of the formed beam to 0 by the beam forming mechanism.

As described above, according to the present embodiment, the moving speed of the stage 25 is monitored, and when the stage speed falls below a certain value, an interrupt signal is generated so that the beam size becomes substantially zero by the beam forming mechanism. Forming deflector 19
Is controlling. Therefore, even when the stage speed is 0 (stopped) or becomes slow under the condition that the forming beam is blanked by the blanking mechanism, unnecessary exposure due to the leak beam can be prevented, and the reliability of the pattern can be improved. Can be measured.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
It is a schematic structure figure showing the electron beam lithography device concerning an embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, there is provided a stage speed monitoring circuit 28 for monitoring the moving speed of the stage 25 from the laser interference circuit 26 for measuring the stage position. The monitoring circuit 28 operates a timer when the stage 25 stops, and generates an interrupt signal when the next movement is not performed within a predetermined time.

Upon receiving the interrupt signal, the computer 11 sends a signal for setting the beam size to 0 to the shaping deflector 19 through the deflection control circuit 13 and the shaping deflection amplifier 14. Then, the light is deflected until the image of the first shaping aperture 18 is formed outside the second shaping aperture 20.

In this state, since the image of the first shaping aperture 18 does not illuminate the opening of the second shaping aperture 20, the leakage of the beam is very small as compared with the normal state, and the amount of the leak beam is also small. . Therefore, unnecessary exposure due to the leak beam can be prevented even when the stage is stopped.

As described above, in this embodiment, the stage 25
Is monitored, and when the stage 25 stops for a predetermined time or longer, an interrupt signal is generated to control the beam size to zero. In this case, when the stop time of the stage 25 is short and the influence of the leak beam is not a problem, the beam size is not controlled by the beam forming mechanism, so that unnecessary beam size changes are eliminated and the adverse effect of the leak beam is avoided. can do.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
It is a schematic structure figure showing the electron beam lithography device concerning an embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, the computer 11 sends various commands to the stage controller 27 according to the drawing stage. Stage controller 2
7 moves or stops the stage 25 according to the command.

For example, in continuous moving writing, the entire pattern is divided into strip-shaped areas called stripes, and writing is performed with stripe writing as the minimum unit. To draw one stripe, first place Stage 2 at the start of the stripe.
Move 5 and stop. After performing appropriate initialization for the drawing circuit, the drawing circuit is started. Next, the stage 25 is moved at a constant speed with the final position of the stripe as a target position, and when the target position is reached, the stage 25 is stopped.

When the stage controller 27 confirms that the stage has stopped at the target position, it enters a state of receiving the next command. Therefore, stage controller 2
7 can know the time when the stage 25 has stopped, and can also know the time since the stage 25 stopped.
When the time that the exposure by the leak beam becomes a problem has elapsed since the stage 25 was stopped as described above, an interrupt signal is sent to a computer or the like.

The computer 11 sends an interrupt signal to the shaping deflector 1
9 is deflected until the image of the first shaping aperture 18 forms an image outside the second shaping aperture 20. In this state, since the image of the first shaping aperture 18 does not illuminate the opening of the second shaping aperture 20, the leakage of the beam is very small as compared with the normal state, and the amount of the leak beam is also small. Therefore, even when the stage 25 is stopped, unnecessary exposure due to the leak beam can be prevented.

As described above, in this embodiment, the stage 25
Since the stop time of (1) is monitored, the effect of the leak beam can be prevented under any conditions. Note that the present invention is not limited to the above embodiments. In the embodiment, the beam is controlled to be substantially zero by the beam shaping means when the stage is stopped or when the stage is stopped for a certain period of time. Instead, a voltage higher than the normal blanking voltage is applied to the blanking electrode. May be applied. Specifically, as shown in FIG. 4A, the high voltage HV is separately set from the blanking voltage BLK.
And BLK is set to H by the interrupt signal.
V may be switched. In addition, as shown in FIG. 4B, a negative high voltage may be applied to the counter electrode of the BLK application electrode of the blanking electrode formed of a parallel plate electrode separately from the normal ground potential.

In the embodiment, the blanking electrode 21
And first and second forming apertures 1 for beam forming.
Although it is provided on the sample side with respect to the beam forming means including the electrodes 8 and 22 and the shaping deflection electrode 19 and the like, the present invention is not limited to this, and the blanking means may be provided on the electron gun side with respect to the beam forming means. In addition, various modifications can be made without departing from the scope of the present invention.

[0036]

As described above in detail, according to the present invention, the beam size is controlled to substantially zero by the beam shaping means when the movement of the stage is stopped or the stopped state continues for a certain period of time, or By blanking the beam with a higher voltage than normal blanking, unnecessary exposure due to a leak beam can be prevented, and a pattern error can be eliminated to improve the reliability of the pattern.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an electron beam writing apparatus according to a first embodiment.

FIG. 2 is a schematic configuration diagram showing an electron beam writing apparatus according to a second embodiment.

FIG. 3 is a schematic configuration diagram showing an electron beam writing apparatus according to a third embodiment.

FIG. 4 is a schematic diagram for explaining a modified example of the present invention.

FIG. 5 is a schematic configuration diagram showing a conventional variable shaped beam type electron beam writing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Control computer 12 ... Data development circuit 13 ... Deflection control circuit 14 ... Shaping deflection amplifier 15 ... Main deflection amplifier 16 ... Sub deflection amplifier 17 ... Electron gun 18 ... First shaping aperture 19 ... Shaping deflection electrode 20 ... Second shaping aperture Reference Signs List 21 blanking electrode 22 blanking aperture 23 main deflection electrode 24 auxiliary deflection electrode 25 sample stage 26 laser interferometer (position and speed detection circuit) 27 stage controller 28 stage speed monitoring circuit

Claims (5)

[Claims] An electron beam writing apparatus for writing a pattern with a variable shaped beam while continuously moving a stage, comprising: a beam shaping means for shaping a beam emitted from an electron gun into a predetermined shape; Beam scanning means for scanning on the sample surface, blanking means for blanking a beam on the electron gun side or on the sample side than the beam shaping means, stage driving means for moving a stage on which the sample is mounted, and Stage speed monitoring means for monitoring the moving speed of the stage, and an interrupt signal generating circuit for generating an interrupt signal when the monitoring means determines that the moving speed of the stage satisfies a predetermined condition. An electron beam writing apparatus characterized by comprising: 2. An electron beam writing apparatus for writing a pattern with a variable shaping beam while continuously moving a stage, comprising: a beam shaping means for shaping a beam emitted from an electron gun into a predetermined shape; Beam scanning means for scanning on the sample surface, blanking means for blanking a beam on the electron gun side or on the sample side relative to the beam shaping means, stage driving means for moving a stage on which the sample is mounted, and An interrupt signal generating circuit for generating an interrupt signal when a stop command is issued to the stage by the stage driving means and the next move command is not issued within a preset time when the command is completed. An electron beam writing apparatus, comprising: 3. An electron beam drawing apparatus according to claim 1, wherein an interrupt signal from said interrupt signal generating circuit is received, and said beam shaping means controls the size of the shaped beam to substantially zero. apparatus. 4. The beam blanking device according to claim 1, wherein upon receipt of an interrupt signal from said interrupt signal generating circuit, said blanking means blanks the beam at a higher voltage than normal blanking. Electron beam drawing equipment. 5. A beam shaping means for shaping a beam emitted from an electron gun into a predetermined shape; a beam scanning means for scanning the shaped beam on a sample surface; and an electron gun or sample side with respect to the beam shaping means. A blanking means for blanking a beam, a stage driving means for moving a stage on which a sample is mounted, and a stage speed monitoring means for monitoring a moving speed of the stage, and a variable shaped beam while continuously moving the stage. In the electron beam writing apparatus for writing a pattern, the beam size is substantially changed by the beam shaping means under the condition that the beam is blanked by the blanking means and when the stop of the stage is detected by the monitoring means. An electron beam writing apparatus, wherein the electron beam writing apparatus is controlled to 0.