JPS60262420A - Electron beam drawing method and device therefor - Google Patents

Abstract

PURPOSE:To correct drawing pattern data as they are compressed without using a computer and to perform the electron beam drawing effectively, by using a proximity effect correcting circuit in combination with a hardware provided in the electron beam drawing device. CONSTITUTION:The drawing pattern data read in a disk 2 are temporarily stored in a buffer memory 3. Each proximity effect data area of the data thus stored is sent out to be developed to a shot data by a compressed data developing circuit 4, and delivered to a correcting system through a mode switching switch 5. The shot data is sent to a bit map memory 6 (11) which has been cleared to zero, where it is converted to a shot image 12 and recorded. Among the data written in the memory 6, only the data used actually are again developed by the developing circuit 4 to shot data 13 and the address of a proximity effect affecting range 14 is calculated by an irradiation quantity computing circuit 7 and sent to the memory 6. The memory 6 reads out these data successively in a work line unit 15 and convert them into bit number data. Simultaneously, the bit number data is multiplied by a proximity effect coefficient to obtain a quantity of proximity effect on the subject word line, and an appropriate irradiation is recorded in the disk 2. When all the necessary processing operation is finished, the switch 5 is changed over to the printing mode so that the pattern data in the memory 3 are developed by the developing circuit 4. The data are sent to a stage control system and electron beam deflecting system 9, and blanked by a blanking system 10 according to the data from the irradiation memory 8, so that the electron beam drawing is performed effectively.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an electron beam lithography method and apparatus for irradiating a substrate such as a semiconductor integrated circuit with an electron beam to draw a button on the substrate. The present invention relates to an electron beam lithography method and apparatus which is developed into individual shot data and controls the electron beam based on the shot data to rapidly process external proximity effect correction when drawing a desired pattern.

[Background of the invention]

An electronic computer is usually used to convert the design data into batten data for electron beam lithography. The conventional baton data is as follows: p is the electron beam irradiation dose, X+ yr is the initial position of the shot, w and h are the width and height of the shot (ps X+ yr
Wr h), or further the repetition pitch and number of shots as dx, dY+ nX, ny
As (P + X + Y + Wgh, dx
.

It has a basic compression structure of dyy nX + nY). 1 Megabit Dynamic RA with 1 Batanurur
For example, when using a computer with IMips processing capacity, the processing time for converting M design data into batten data for electron beam lithography is as follows: design data input 2 contouring, proximity effect correction, shot division, batten data It takes a total of about 200 minutes for all layers to output. Proximity effect correction includes a dose correction that is called internal proximity effect correction that is based on the area of the batten, and a dose correction that also takes into consideration the proximity effect from the slams in the vicinity of the slam, which is called external proximity effect correction. When the slam rule is 1 cape or more, it is possible to form a slam with the required accuracy only by correcting the internal proximity effect determined by the slam area.
For electron beam lithography in the submicron region, it is necessary to apply external proximity effect correction to the baton data. External proximity effect correction processes not only the area of the baton itself, but also the areas and distances between the three shots that make up the baton and surrounding shots, so the processing time is short. increases in proportion to the square of the number, and the batan data transformation is
When carried out using an electronic computer with a Mips processing capacity, the processing time has the disadvantage of being long, approximately 200 hours per layer.

Furthermore, since the irradiation amount of each shot changes by applying external proximity effect correction, it is difficult to use the conventional basic compressed button data format, resulting in an increase in the amount of data.

[Purpose of the invention]

It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art.
The basic structure (X + 3' + w, h) or compressed data structure (X r Y + Wr
h y dx, dy+ nx, ny).

Electron beam lithography 4--Both methods and methods in which the electron beam lithography button data having this data structure is developed in the form of shot data on a bitmap memory, and this shot data is subjected to internal proximity effect correction and external proximity effect correction at high speed and recorded. The goal is to provide equipment.

[Summary of the invention]

A feature of the present invention is that in an electron beam drawing method in which batten data is developed into individual shot data and the electron beam is controlled based on this shot data to draw a desired batten, the above shot data is write to memory,
External proximity effect correction is applied to this shot data to generate dose data, and after this dose data is recorded in the dose memory, actual drawing is performed based on this dose data and the slam data. An electron beam lithography method, a magnetic disk device and a buffer memory device for storing baton data, a decompression circuit for decompressing the baton data into individual shot data, and an electron beam lithography method for controlling the electron beam based on the shot data. In an electron beam lithography apparatus that is equipped with a beam deflection device and an electronic computer that controls each of the devices and draws a desired baton, a mode in which a processing mode is switched by changing the destination of the shot data connected to the expansion circuit. It is composed of a changeover switch, a memory connected by this mode changeover switch to store shot data, a dose calculation circuit connected to this memory, and a dose memory connected to this dose calculation circuit,
Before actual drawing, the mode changeover switch is switched to a dose calculation state to generate dose data of the shot data.

Thereafter, the mode changeover switch is switched to a drawing state, and the electron beam lithography apparatus performs actual drawing based on the slam data and the irradiation amount data.

[Embodiments of the invention]

An embodiment of the present invention will be described using FIGS. 1 to 6.

The drawing button data is usually in a compressed format to reduce the amount of data, and is divided into blocks in units of subfields. Since the proximity effect correction circuit of the present invention performs proximity effect correction on a subfield basis, drawing data approximately 10 μm outside the subfield is also stored in the buffer memory together with data within the subfield as drawing batten data. Data outside this subfield is used only for proximity effect correction.

Not used for actual drawing. Distinguishing between data within a subfield and data outside the subfield that is not drawn can be easily realized by providing an appropriate flag to the button data when converting the drawing button data by an electronic computer. Hereinafter, the subfield will be referred to as a proximity effect correction field, and the area including the subfield and data outside the subfield will be referred to as a proximity effect data field (FIG. 1).

The flow of the process is shown in Figure 2. The processing flow is 1: In the processing step (a), storing the drawing button data in the buffer memory.

2: In step (b), the compressed data expansion circuit develops all the drawing button data in the proximity effect data field into shot data, and in (c), the development of all the shot data in the proximity effect data field to the bitmap memory. writing.

3: In step (d), the proximity effect correction field white drawing batande footer is developed into shot data by the compressed data expansion circuit, and in (e), the proximity effect influence range of the shot data is calculated by the dose calculation circuit. In , and (f), reading the shot data within the proximity effect influence range from the bitmap memory, and in (g), calculating the dose of radiation received by the shot data based on the proximity effect correction, and calculating the shot data from this dose. calculation of the appropriate irradiation amount, and writing the appropriate irradiation amount into the irradiation amount memory in (h).

4: Judgment of whether all shots in the proximity effect correction field are completed in the judgment process (S), and in (N),
Determine whether all proximity effect correction fields are finished.

5; In the processing step (1), the compressed data expansion circuit develops the drawing data in the proximity effect correction field into shot data, and reads out the dose from the dose memory and writes.

Consists of.

Explanation will be added using FIGS. 3 and 4. The drawing button data read into the magnetic disk 2 is as follows.

8- Read into buffer memory 3 prior to proximity effect correction processing. The data in the buffer memory 3 is sent for each proximity effect data field to the compressed data expansion circuit 4, where it is expanded into shot data consisting of electron beam position data, rectangular side length data, and the like. When writing the bitmap memory during proximity effect correction processing, the mode changeover switch 5 sends shot data to the proximity effect correction processing system. Shot data is stored in bitmap memory 6 with all bits cleared in advance.
(11 in Figure 4), where it is converted into a simmit image consisting of a set of bits 1 and recorded (12).
).

FIG. 5(a) shows a block diagram of an example of the configuration of a bitmap memory used in this embodiment, and FIG. 5(b) shows a block diagram of an example of the configuration of a selector circuit.

The bitmap memory used in this embodiment selects a plurality of consecutive word lines and bit lines from four pieces of address information, two for word lines and two for bit lines.
Since it has a function of simultaneously selecting memory cells surrounded by these, one shot data is recorded as a shot image in one memory cycle. Furthermore, since it has a function of selecting the outputs of a plurality of consecutive sense amplifiers, it is possible to read a plurality of consecutive bits on a word line in one memory cycle.

After writing all the data in one proximity effect data field to the bitmap memory, the actual drawing in the proximity effect correction field in the same proximity effect data field is performed again in order to calculate the appropriate dose for each shot data. Data expansion circuit 4 compresses only the button data used for
Expand it to Shoku1-data. This shot data is sent to the dose calculation circuit 7 by the mode changeover switch 5.

From this shot data (13), the dose calculation circuit 7 calculates
The address on the bitmap memory of the proximity effect influence range (14) in which there is a shot that exerts a proximity effect on the shot of interest is calculated and sent to the bitmap memory 6 (11). Based on this, the bitmap memory 6 stores bit information within the influence range in units of word lines (15
) to read out sequentially16).

This bit information is converted into bit number information for each appropriate bit width. This can be determined by counting the number of bits or by reading the memory into which the number of bits has been written, regarding the bits as an address.

The amount of influence of the proximity effect is the product of the shot area and a coefficient expressed as a function of the distance between the shot of interest and surrounding shots. The shot you're focusing on also gives you a melee effect. This coefficient can be determined by calculation by a computer or by reading it from a coefficient memory (17) in which coefficients have been calculated in advance. At the same time as bit information is read from the bit map memory (11), the proximity effect coefficient is calculated, and the total of the bit number information and multiplication is 1.
This is the proximity effect amount on the word line. By integrating this over the entire proximity effect influence range, it becomes possible to quickly calculate the proximity effect amount, that is, the irradiation amount received by the shot of interest.

An appropriate dose is determined from the calculated proximity effect amount, and this dose data is recorded in a storage device such as the dose memory 8 or the magnetic disk 2. These processes are performed for each shot data in the 11-proximity effect correction field, and the appropriate dose of each shot is recorded in the dose memory 8. After the processing of one proximity effect correction field is completed, the bitmap memory is cleared and the next proximity effect data field is processed. After completing the processing for all the proximity effect data fields, the mode changeover switch 5 is switched to the drawing state, and the drawing button data in the proximity effect correction field in the buffer memory 3 is expanded into shot data by the compressed data expansion circuit 4, and electronic It is sent to the line deflection system and stage control system 9. at the same time.

The dose data recorded on the shots in the dose memory 8 is sequentially read out and sent to the blanking system 10.

Perform the actual drawing. FIG. 6 shows a block diagram of the dose calculation circuit.

By using this proximity effect correction circuit.

Proximity effect correction processing using an electronic computer is no longer necessary. The processing time using this proximity effect correction circuit was approximately 500 seconds, which was approximately 1400 times faster than similar processing using an electronic computer. The dose data recorded in the dose memory can be used repeatedly for writing on the same chip, so the proximity effect correction process using the proximity effect correction circuit can be completed once on the same chip, reducing the processing time for actual writing. The overhead is negligible.

Although the above embodiment has been described as using a bitmap memory, the present invention is not limited thereto, and the same effect can be produced even if a general memory is used.

[Effects of the Invention] As explained above, the present invention uses a proximity effect correction circuit combined with the hardware included in an electron beam lithography system, thereby producing pattern data for drawing by an electronic computer that takes 9 hours. This method has the advantage that the proximity effect correction process can be executed at high speed without performing the proximity effect correction process, and the drawing button data can remain in a compressed state.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram of data fields used in the present invention.
FIG. 2 is a flowchart of processing according to an embodiment of the present invention, FIG. 3 is a block diagram of an embodiment of the present invention, FIG. 4 is an explanatory diagram of proximity effect processing calculation, and FIG. 5(a) is a diagram of the present invention. (b) is a block diagram of a selector circuit of the bitmap memory used in one embodiment of the present invention, and FIG. 6 is a block diagram of a dose calculation circuit used in one embodiment of the present invention. <Explanation of symbols> 1... Control computer 2... Magnetic disk 3...
Buffer memory 4...Compressed data expansion circuit 5...
Mode selection switch 6.11...Bit map memory 7...Dose calculation circuit 8...Dose memory 9
...Electron beam deflection system and stage control system 10...Blanking system 12...Shot image 13...Shot data 14...Proximity effect range 15...
Word line 16 on bitmap memory...Word line 1
Data 17 on 5... Proximity effect coefficient memory table patent applicant Junnosuke Nakamura, patent attorney representing Nippon Telegraph and Telephone Corporation 15-

Claims (4)

[Claims] (1) Develop pattern data into individual shot data,
In an electron beam lithography method in which a desired pattern is drawn by controlling an electron beam based on this shot data, the shot data is written into a memory before actual lithography, and external proximity effect correction is applied to this shot data. An electron beam lithography method characterized in that after generating irradiation amount data and recording this irradiation amount data in a irradiation amount memory, actual lithography is performed based on this irradiation amount data and the baton data. (2) a magnetic disk device and a buffer memory device that store the baton data; an expansion circuit that expands the baton data into individual shot data; an electron beam deflection device that controls the electron beam based on the shot data; In an electron beam lithography apparatus that draws a desired pattern and includes an electronic computer that controls the apparatus, a mode changeover switch connected to the expansion circuit changes the destination of the shot data and changes the processing mode; It consists of a memory that stores shot data connected by a switch, a dose calculation circuit connected to this memory, and a dose memory connected to this dose calculation circuit. switch to a dose calculation state to generate dose data of the shot data,
The electron beam lithography apparatus is characterized in that the mode changeover switch is then switched to a drawing state and actual drawing is performed based on the slam data and the irradiation amount data. (3) The memory selects a plurality of consecutive word lines and bit lines from a total of four pieces of address information, two for word lines and two for bit lines, and simultaneously operates memory cells surrounded by these. 3. The electron beam lithography apparatus according to claim 2, wherein the memory has a selector circuit for selecting and a multiplexer circuit for selecting outputs from a plurality of consecutive sense amplifiers. (4) The dose calculation circuit is a dose calculation circuit that includes a plurality of multipliers and a plurality of adders and executes calculations between data from the memory and a proximity effect correction coefficient given in advance in parallel. An electron beam lithography apparatus according to claim 2 or 3, characterized in that: