JP3623671B2 - Charged particle beam writing method and apparatus - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a charged particle beam drawing method and apparatus for improving pattern drawing accuracy.
[0002]
[Prior art]
An electron beam lithography system is a device that can draw a predetermined pattern at a predetermined position of a material to be drawn by shooting an electron beam at a predetermined position on the material to be drawn. I can do it.
[0003]
One of the electron beam drawing methods is a spot beam drawing method. This method is a method of drawing each desired pattern on the drawing material by scanning each predetermined range on the drawing material with an electron beam having a circularly narrowed cross section. FIG. 1 schematically shows an electron beam drawing apparatus. An electron beam from an electron gun 1 is focused on a drawing material 3 by a focusing lens 2. The data memory 4 stores drawing pattern data that is field-divided (division of a region in which a pattern can be drawn only by deflection of an electron beam without performing stage movement). Rectangular and trapezoidal division (for example, division is performed in parallel with the X axis starting from each corner of the drawing pattern figure). Each divided rectangular and trapezoid pattern data (consisting of the position, size, shape, etc. of each pattern) is sent to the scanning signal generating circuit 6. The scanning signal generation circuit generates a scanning signal for drawing each rectangular pattern or trapezoid pattern. For example, taking a rectangular pattern as shown in FIG. 2 as an example, an X-direction scanning signal, a Y-direction scanning signal, and blanking are based on the position (X1, Y1) and dimension (Xa, Ya) data of the rectangular pattern. A control signal is generated, the X direction scanning signal is sent to the X direction DA converter 7X, the Y direction scanning signal is sent to the Y direction DA converter 7Y, and the blanking control signal is sent to the blanking electrode 9 via the blanking amplifier 8. Each supply. The X direction scanning signal and the Y direction scanning signal are converted into analog signals by the X direction DA converter 7X and the Y direction DA converter 7Y, respectively, and then the X direction deflector via the X direction amplifier 10X and the Y direction amplifier 10Y, respectively. 11X and Y direction deflector 11Y. FIGS. 3A and 3B show the X-direction scanning signal and the Y-direction scanning signal which are converted into analog signals, respectively. In FIG. 1, 9S is a blanking stop.
[0004]
Therefore, the electron beam focused on the drawing material 3 by the deflection action of the X direction deflector 11X and Y direction deflector 11Y shows the range of Xa, Ya starting from (X1, Y1) on the material. Therefore, the rectangular pattern is drawn on the drawing material. When such pattern drawing proceeds and drawing of the graphic pattern in one field is completed, the stage (not shown) on which the drawing material is placed is moved so that the next field is on the optical axis, As described above, graphic pattern drawing by electron beam irradiation is repeated.
[0005]
[Problems to be solved by the invention]
However, the DA converter has a characteristic of temporarily generating a large spike (large noise) during DA conversion. This spike is called a glitch.
[0006]
If such a glitch is generated in the DA-converted scanning signal, the beam scanning by the deflector is disturbed, and as a result, the drawing accuracy of the graphic pattern is lowered.
[0007]
An object of the present invention is to provide a novel charged particle beam writing method and apparatus for solving such problems.
[0008]
[Means for Solving the Problems]
In the charged particle writing method according to the first aspect of the present invention, pattern data to be drawn is sent to a deflector via a DA converter, thereby scanning a region based on the data on the drawing material with a charged particle beam. Thus, in the charged particle beam drawing method for drawing a desired pattern on the drawing material, the pattern to be drawn is divided based on the glitch generation position of the DA converter. To do.
[0009]
The charged particle beam drawing apparatus according to the second aspect of the invention scans a region based on the data on the drawing material with the charged particle beam by sending pattern data to be drawn to the deflector via the DA converter. Thus, in the charged particle beam drawing apparatus configured to draw a desired pattern on the drawing material, the glitch position data of the DA converter is set, and the pattern to be drawn is the glitch occurrence position. And a division circuit configured to divide the pattern to be drawn at the position of the glitch when it is determined to straddle, and is divided by the division circuit. Data is sent to the deflector via the DA converter.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 4 shows an example of an electron beam drawing apparatus according to the present invention. In the figure, the same reference numerals as those used in FIG. 1 denote the same components.
[0012]
The difference between the configuration of the electron beam lithography apparatus shown in FIG. 4 and the configuration of the electron beam lithography apparatus shown in FIG. This will be described below.
[0013]
As a result of pursuing the generation of glitches during the DA conversion, it has been found that, for each bit of data set in the DA converter, the number of bits to be changed is large, and it is greatly generated when higher bits change. In an electron beam drawing apparatus, normally, 8-bit data expressed in hexadecimal is often used as drawing data. For example, when 8-bit data expressed in hexadecimal is converted to DA. , 7F (binary, 01111111) to 80 (binary, 10000000) is the largest, then between 3F (binary, 00111111) and 40 (binary, 01000000) and BF It is between (binary number 10111111) and C0 (binary number 11000000). The latter glitch is smaller than the former and can be ignored depending on the required drawing accuracy. For example, when the drawing area on the drawing material is divided into a large number of chips and the position coordinates on each chip are divided by 8-bit fineness, the pattern to be drawn in each chip is the coordinates of 7F and 80 in hexadecimal numbers. In the case of a figure straddling, if it is affected by a glitch without any contrivance as in the prior art, the scan in the X direction is disturbed by the glitch between the coordinates of 7F and 80 as shown in FIG. As a result, the electron beam dose amount becomes non-uniform in the pattern to be drawn, resulting in exposure spots. For convenience of explanation, the case where a glitch occurs only in the X direction has been described, but the Y direction also occurs in the same manner.
[0014]
Therefore, since the location where the glitch occurs can be known in advance, when the glitch occurrence position is set in advance and divided into rectangles and trapezoids, the figure is divided so as not to straddle the glitch occurrence position, and the glitch occurs At this point, it is only necessary to prevent the electron beam from being shot on the material.
[0015]
In accordance with this principle, when the figure dividing circuit 50 is determined to straddle the memory 51 that stores the glitch occurrence position, the determination circuit 52 that determines whether or not the input drawing pattern straddles the glitch occurrence position The dividing circuit 53 is configured to divide into a rectangular / trapezoidal pattern with the glitch position as a boundary.
[0016]
Next, the operation of the electron beam drawing apparatus having such a configuration will be described.
Data of the drawing figure divided into fields from the data memory 4 is input to the figure dividing circuit 50. This data consists of data such as the position of each corner and the size of each side of the figure, and is divided into a rectangular pattern figure and a trapezoid pattern figure by the dividing circuit 53 in the subsequent stage. In 52, it is determined whether or not the drawing pattern straddles the glitch occurrence position by comparing the glitch position data from the memory 51 with the drawing pattern data. In this determination, when it is determined that the drawing pattern is not a figure straddling the glitch position, the dividing circuit divides the rectangle and trapezoid as it is, and each of the divided trapezoid and rectangle pattern data (position, size, Is sent to the scanning signal generation circuit 6. On the other hand, when it is determined that the drawing pattern is a figure straddling the glitch position, the dividing circuit first divides the drawing pattern into a rectangle / trapezoid pattern with the glitch position from the memory 51 as a boundary, and then a normal rectangle. -Perform trapezoidal division. In addition, after performing normal rectangular / trapezoidal division, division may be performed with the glitch position as a boundary.
[0017]
FIG. 6 shows a rectangular pattern that is divided into rectangles and trapezoids with a glitch position as a boundary. The rectangular pattern P1 is divided into two rectangular patterns Pa and Pb at the boundary between 7F and 80 where the glitch occurs.
[0018]
The data of the rectangular patterns Pa and Pb divided in this way is sent to the scanning signal generation circuit 6. The scanning signal generation circuit generates a scanning signal for drawing each rectangular pattern or trapezoid pattern. That is, an X direction scanning signal, a Y direction scanning signal, and a blanking control signal are created based on the position and size data of each rectangular pattern Pa, Pb, and the X direction scanning signal is sent to the X direction DA converter 7X. The direction scanning signal is supplied to the Y-direction DA converter 7Y, and the blanking control signal is supplied to the blanking electrode 9 via the blanking amplifier 8. The X direction scanning signal and the Y direction scanning signal are converted into analog signals by the X direction DA converter 7X and the Y direction DA converter 7Y, respectively, and then the X direction deflector via the X direction amplifier 10X and the Y direction amplifier 10Y, respectively. 11X and Y direction deflector 11Y. FIGS. 3A, 3B, and 3C show an X-direction scanning signal, a Y-direction scanning signal, and a blanking control signal that are converted into analog signals, respectively.
[0019]
Thus, as shown in FIGS. 6 and 8, the electron beam focused on the drawing material 3 by the action of the X direction deflector 11X and the Y direction deflector 11Y is first (X2, Y2 on the material). ) To scan the range of Xb and Yb. When the scanning is finished, blanking is once applied to the electron beam, and immediately after that, the range of Xc and Yc is scanned starting from (X3, Y3) on the material. As shown in the X-direction scanning signal of FIG. 7A and FIG. 7B, a glitch is generated during blanking. As a result, a rectangular pattern without the influence of the glitch is drawn on the drawing material. become. When such pattern drawing proceeds and drawing of the graphic pattern in one field is completed, the stage (not shown) on which the drawing material is placed is moved so that the next field is on the optical axis, As described above, graphic pattern drawing by electron beam irradiation is repeated.
[0020]
In the above embodiment, for the sake of convenience of explanation, a glitch at the time of scanning in the X direction is considered, but a glitch at the time of scanning in the Y direction is processed in the same manner.
[0021]
In the above embodiment, a relatively large glitch is considered as a problem, and a relatively small glitch is ignored. However, in order to increase the drawing accuracy, a relatively small glitch is also taken up, and as in the above embodiment, such a glitch position is taken up. The drawing pattern may be further finely divided on the boundary.
[0022]
In the above embodiment, the electron beam lithography apparatus has been described as an example, but it goes without saying that the present invention is also applicable to an ion beam lithography apparatus.
[Brief description of the drawings]
FIG. 1 shows an example of a conventional electron beam drawing apparatus.
FIG. 2 shows an example of pattern drawing by electron beam scanning.
FIG. 3 shows an example of a waveform of a scanning signal in conventional drawing.
FIG. 4 shows an example of pattern drawing by electron beam scanning when affected by a glitch.
FIG. 5 shows an example of an electron beam drawing apparatus of the present invention.
FIG. 6 shows an example of drawing figure division according to the present invention.
FIG. 7 shows a waveform example of a scanning signal in drawing according to the present invention.
FIG. 8 shows an example of pattern drawing by electron beam scanning according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Condensing lens, 3 ... Drawing material, 4 ... Data memory, 50 ... Graphic division circuit, 51 ... Memory, 52 ... Judgment circuit, 53 ... Dividing circuit, 6 ... Scan signal generation circuit, 7X ... X direction DA converter, 7Y ... Y direction DA converter, 8 ... Blanking amplifier, 9 ... Blanking electrode, 10X, 10Y ... Amplifier, 11X ... X direction deflector, 11Y ... Y direction deflector

Claims (2)

By sending pattern data to be drawn to a deflector via a DA converter, a region based on the data on the drawing material is scanned with a charged particle beam, thereby drawing a desired pattern on the drawing material. In the charged particle beam drawing method, the charged particle beam drawing method is configured to divide the pattern to be drawn based on a glitch generation position of the DA converter. By sending pattern data to be drawn to a deflector via a DA converter, a region based on the data on the drawing material is scanned with a charged particle beam, thereby drawing a desired pattern on the drawing material. In the charged particle beam drawing apparatus configured as described above, the data of the glitch position of the DA converter is set, and it is determined whether the pattern to be drawn is a pattern drawn at a position across the glitch occurrence position, A division circuit configured to divide a pattern to be drawn when it is determined to straddle is divided at the glitch position, and the data divided by the division circuit is sent to the deflector via the DA converter. The resulting charged particle beam lithography system.

Images