JP2002043212A - Method for electron beam lithography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for variable area electron beam lithography, by which the verification of the output data of an electron beam lithography system can be performed relatively easily without relying upon the outputting order of the data. SOLUTION: An output data storing section 33 finds the area of a rectangle from the rectangle size data of a divided written picture and holds the found area data by storing the data at a memory address 36 at every prescribed area and a control CPU compares the held data with the data obtained through normal processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable area type electron beam drawing method for projecting a desired shape by projecting an electron beam having a rectangular shape or the like onto a material to be drawn. The present invention relates to a writing data abnormality detection method in a variable area type electron beam writing method which detects an abnormality in a conversion process.

[0002]

2. Description of the Related Art FIG. 1 shows a drawing apparatus using a conventional variable area type electron beam drawing method. 1 is electron beam E
The electron beam EB generated from the electron gun 1 is emitted to the first forming aperture 3 through the illumination lens 2. The aperture image of the first shaping aperture is formed on the second shaping aperture 6 by the shaping lens 4, and the position of the image can be changed by the shaping deflector 5. The image formed by the second forming aperture 6 is irradiated onto the drawing material 10 via the reduction lens 7 and the objective lens 8. The irradiation position on the drawing material 10 can be changed by the positioning deflector 9.

[0003] Reference numeral 11 denotes a computer. The computer 11 transfers pattern data from a pattern data memory 12 to a data transfer circuit 13. Data transfer circuit 1
3 is supplied to the shot divider 14 to be divided into shots. A signal corresponding to the drawing data from the shot divider 14 is supplied to a deflection amplifier 16 for supplying a deflection voltage to the shaping deflector 5 via a DA converter 15,
A deflection amplifier 18 for supplying a deflection voltage to the positioning deflector 9 via a converter 17 and an electron gun 1 via a DA converter 19
Is supplied to a blanking control circuit 21 for controlling a blanking electrode 20 for blanking an electron beam generated from the above.

[0004] A computer 11 controls a drive mechanism 23 of a stage 22 on which the material 10 is placed for moving the material in each field. The movement amount of the stage 22 is measured by the laser length measuring device 24, and the measurement result is supplied to the computer 11. Irradiation of the material 10 with the electron beam EB generates secondary electrons and reflected electrons. For example, the reflected electrons are detected by a pair of reflected electron detectors 25. After the detection signal of the backscattered electron detector 25 is added by the adder 26, the mark signal processing device 2
7 is supplied. 28 is a deflector control circuit. The deflector control circuit 28 is controlled by the computer 11, and a signal generated from this circuit is supplied via a DA converter 17 to a deflection amplifier 18 that supplies a deflection voltage to the positioning deflector 9. The operation of such a configuration will now be described.

First, a normal drawing operation will be described.
The pattern data stored in the pattern data memory 12 is sequentially read out and supplied to the shot divider 14 via the data transfer circuit 13. Based on the data divided by the shot divider 14, the shaping data of the electron beam is DA
The signal is supplied to the deflection amplifier 16 via the converter 15, and the signal amplified by the amplifier 16 is supplied to the shaping deflector 5. The deflection signal of the electron beam according to the drawing pattern is supplied to the deflection amplifier 18 via the deflector control circuit 28 and the DA converter 17, and the signal amplified by the amplifier 18 is supplied to the positioning deflector 9. You.

As a result, the cross section of the electron beam is formed into a rectangular shape having a desired area by the shaping deflector 5 based on each divided pattern data, and the beam having the rectangular cross section is supplied to the positioning deflector 9. The shot is sequentially made on the material in accordance with the deflection signal, and a pattern drawing of a desired shape is performed. At this time, the blanking of the electron beam is executed in synchronization with the shot of the electron beam on the material 10 by the blanking signal from the blanking control circuit 21 to the blanking electrode 20.

The drawing operation by the deflection of the electron beam is performed in units of fields. After drawing in a specific field is completed, the stage 22 is moved by the length of the field by the driving mechanism 23, and the next step is performed. The field is drawn. The amount of movement of the stage 22 is measured by the laser length measuring device 24, and the measured value is supplied to the computer 11. The computer 11 controls the drive mechanism 23 based on the measured movement amount, and enables the accurate movement of the stage 22.

FIG. 6 shows the outline of the figure dividing process in the shot divider 14. FIG. 6A shows input data. Such input data is divided into figures each having a size equal to or smaller than the maximum size of the rectangular electron beam. FIG. 6B shows an example of the divided data. Further, when a trapezoid is included in the data shown in FIG. 6B, the trapezoid is developed into a rectangular rectangle. FIG. 6C shows data obtained by converting a trapezoidal figure into strip-shaped rectangular data. FIG.
Each figure is drawn based on the data of (c).

[0009]

In the above-described electron beam drawing apparatus, the figure dividing process in the shot divider 14 needs to be performed at a very high speed, and this conversion process becomes complicated, and the reliability of the device becomes high. From the viewpoint of ensuring security and maintainability, it has become important to verify that the conversion process has been performed correctly.

That is, when manufacturing a device, it is required to confirm whether the conversion operation is normal or abnormal, and to identify the cause of any trouble in the device. . Therefore, it is necessary to verify the output data after performing the conversion process. However, the number of output data is very large, and in order to verify all data, it is necessary to calculate normal output data from input data, which requires considerable processing.

Until now, output data when certain input data is input to a normal device is stored, and in the above case, the output data is compared with the output data when the same data is input. The above objective was achieved. However, with the recent miniaturization of drawing data, the amount of data expressing graphics has increased, and the amount of output data has also increased.
Therefore, this method has a disadvantage that the capacity of a memory prepared for taking in all output data becomes enormous.

For example, in a step-and-repeat type drawing apparatus, drawing is performed in a unit called a single field. However, even if only all the data contained in this field is taken in, a memory of several hundred Mbytes on average is required. However, depending on how to create the input data, there may be a case where the number of data becomes larger. In order to speed up the conversion process, parallel processing may be used. However, in this case, the order in which the data is output is not necessarily a fixed order, so that the above verification method cannot be used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and a variable area type electron beam writing method capable of relatively easily verifying output data of a writing apparatus without depending on the data output order. It is to realize.

[0014]

According to a first aspect of the present invention, there is provided a variable area type electron beam writing method which divides a writing pattern based on writing data and changes a cross-sectional shape of the electron beam in accordance with the drawing figure after the division. In a variable area type electron beam writing apparatus configured to project a formed rectangular electron beam onto a desired position on a material to be drawn to draw a desired pattern, The area of the rectangle is obtained from the size data, the obtained area data is accumulated and held in the memory address of each predetermined area, and the held data is compared with data obtained by performing normal processing in advance. Features.

According to the first aspect of the present invention, the area of the rectangle is obtained from the rectangular size data of the drawing figure after division, the obtained area data is accumulated and held in the memory address of each predetermined area, and the held data and the normal Since the data obtained by performing the processing is compared with the data, it is possible to detect a malfunction or the like of the data conversion processing. As a result, the reliability of data processing in the drawing apparatus is improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the X position and the Y position for specifying the position of the drawing figure are set.
Since a part of the position data is extracted and combined, and the combined data is used as a memory address, the data can be accumulated collectively in a certain range, and the data amount can be reduced.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows an example of a main part of a variable area type electron beam writing apparatus for carrying out the method of the present invention. The input pattern data is supplied to a data conversion processing circuit (shot divider) 14, where it is divided into figures for each shot of the electron beam on the material to be drawn.

The output of the data conversion processing circuit 14 is sent to each control circuit of the electron beam writing apparatus main body 32 via the control amplifier 31. Each control circuit includes a blanking control circuit 21, an amplifier 16, a deflector control circuit 28,
A converter. Further, the output of the data conversion processing circuit 14 is also supplied to the output data storage unit 33.

The output data storage section 33 comprises a multiplier 34, an adder 35, a memory 36, and switches 37 and 38. The output data converted by the data conversion processing circuit 14 are all rectangular data. As shown in FIG. 3, the rectangular data P is a graphic position X, Y on a two-dimensional coordinate and a width W and a height of the rectangle. It is represented by H data. These four types of data are sent to the control amplifier 32 and at the same time to the output data storage unit 33.

In the above-described configuration, first, when the apparatus is operating normally, specific input data is drawn, and data obtained for each field is read and stored by the control CPU 39. Thereafter, when the device is in an abnormal or unknown state, similar data is obtained and compared. If the data match, it can be determined that the conversion process of the device is normal.
At this time, the switches 37 and 38 are connected to the terminal A.

Next, the contents of the above-described determination processing will be described in more detail. In the output data storage unit 33, first, all the contents of the memory 36 are set to 0 before the processing. When the output data from the data conversion processing circuit 14 is input,
The lower bits of the X and Y position data are discarded, and a memory address is synthesized. This is shown in FIG. This is to collectively accumulate data in a certain range and reduce the data amount. The synthesized address data is input to the memory 36 via the switch 37.

For example, 1 μm in a 1 mm square field
When the data is counted for each direction, the number of data is one million data, and even if 32 bits (4 bytes) are used for one data, the processing can be performed with a data amount of 4 Mbytes.

That is, even if the size of the rectangle is specified in units of 1 nm, the total area of the rectangle having the origin in a 1 μm square area is 16,000,000 nm ² at the maximum when the beam size is 4 μm at the maximum. Can be expressed in 32 bits. Also, figures are usually not overlapped due to the nature of drawing. However, in the case of a trapezoid, it is superimposed and drawn, but at most it is only superimposed about 10 times at one place, so the maximum value of the area is 160,000,000 nm ² ,
Again, expression can be made with 32 bits.

Next, the data of the width W and the height H are multiplied by a multiplier 34.
And calculate the area. At the same time, the data at the combined address is read. When both are complete,
The area data and the read data are added by the adder 35,
It is stored at the same address. By repeating such an operation for all the output data in the field, the area of the drawing figure for each certain area is accumulated.

FIG. 5 shows the state of the memory 36 in a very simple case. The rectangle in which the X coordinate position is 04 and the Y coordinate position is 00 is a simple example. In this case, a rectangle having an area of 1 μm ² is stored in the address 04. X coordinate position is 0
A plurality of rectangles exist at the position where the 3, Y coordinate position is 01. In this case, an area of 2 μm ² is stored in the address 11. The position where the X coordinate position is 04 and the Y coordinate position is 03 is an example in which the rectangle straddles, and in this case, 1 μm ² is stored in the address 28 including the origin of the rectangle.

The control CPU 39 reads and saves this data after drawing of one field is completed. At this time, the switches 37 and 38 are connected to the B terminal. The determination as to whether or not the data conversion processing is normal is made by comparing the data with normal data stored in advance. Note that this data is not the same as the width and height of the output data if only one bit is different. However,
When two or more bits are different, they may coincide by chance.

Also, as for the position data, if only the extracted upper bits differ by one bit, they will not be the same data. Therefore, when only one bit of the output data differs, a malfunction can be always detected. Also, since rectangular data is stored for each specified address, even if the data output order is different,
Since the obtained result is the same, the verification of the conversion processing using the parallel processing can also be performed.

In the above-described verification of the conversion process, since the shot time is not considered at all, it is not possible to detect when the irradiation time of the electron beam becomes abnormal. In that case, if the area is further multiplied by the irradiation time, an abnormality in the irradiation time can be detected.

In addition, as for the address combining, an abnormality can be similarly detected by cutting off the upper bits instead of the lower bits. Furthermore, by preparing two memories, synthesizing the address only from the lower bits that have been cut off in the above-described method, and performing the same accumulation on the added other side, the address can be inspected for all bits. Further, in the above description, the control CPU is used to hold and compare normal data, but it is also possible to perform processing by hardware.

[0030]

As described above, according to the first aspect of the present invention, the area of a rectangle is obtained from the rectangular size data of a drawing figure after division, and the obtained area data is accumulated and stored in a memory address for each predetermined area. Since the stored data is compared with data obtained by performing normal processing in advance, it is possible to detect a malfunction or the like of the data conversion processing. As a result, the reliability of data processing in the drawing apparatus can be improved. Even if the output order of each data is different, the obtained result is the same, so that it is possible to verify the conversion processing using the parallel processing.

According to a second aspect of the present invention, in the first aspect of the present invention, the X position and the Y position for specifying the position of the drawing figure are set.
Since a part of the position data is taken out and combined, and the combined data is used as a memory address, the data can be accumulated collectively in a certain range, and the data amount can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a drawing apparatus using a conventional variable area electron beam drawing method.

FIG. 2 is a diagram showing an example of a main part of a writing apparatus using a variable area electron beam writing method according to the present invention.

FIG. 3 is a diagram showing rectangular data.

FIG. 4 is a diagram for explaining synthesis of X and Y position data.

FIG. 5 is a diagram illustrating a state in which rectangular data is stored in a memory.

FIG. 6 is a diagram showing an outline of a graphic dividing process of a pattern to be drawn.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun 2 Illumination lens 3, 6 Molding aperture 4 Molding lens 5, 9 Deflector 7 Reduction lens 8 Objective lens 10 Material 11 Computer 12 Memory 13 Data transfer circuit 14 Shot divider (Data conversion processing circuit) 15, 17, 19 DA converter 16, 18 Deflection amplifier 20 Blanking electrode 21 Blanking control circuit 22 Stage 23 Drive mechanism 24 Laser length measuring device 25 Backscattered electron detector 26 Adder 27 Mark signal processing circuit 28 Deflector control circuit 31 Control amplifier 32 Drawing Main unit 33 Output data storage unit 34 Multiplier 35 Adder 36 Memory 37 Switch 38 Switch 39 Control CPU

Claims (2)

[Claims] 1. A drawing pattern is divided based on drawing data, a cross-sectional shape of an electron beam is formed into a rectangle according to a drawing figure after the division, and the formed rectangular electron beam is placed at a desired position on a material to be drawn. In the variable area type electron beam writing method in which a desired pattern is drawn by projecting the area, a rectangular area is obtained from the rectangular size data of the drawing pattern after division, and the obtained area data is stored in a memory address for each predetermined area. And an electron beam writing method for comparing the stored data with data obtained by performing normal processing in advance. 2. The electron beam drawing method according to claim 1, wherein a part of the data at the X position and the data at the Y position for designating the position of the drawing figure are respectively taken out and combined, and the combined data is used as a memory address.