JP3258742B2 - Electron beam writing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for writing an electron beam, and more particularly, to a method of processing a figure pattern without reducing the throughput even when handling device pattern data exceeding the capacity of a buffer memory. The present invention relates to an electron beam writing method and apparatus capable of preventing separation, double exposure data, and the like, and capable of correctly performing a proximity effect correction process.

The degree of integration of electronic devices is increasing year by year, and there is a demand for a technology for exposing devices having a size of sub-quarter μm. Electron beam exposure technology is known as a high-resolution exposure technology.However, the exposure time becomes very long as the number of patterns increases, and the position accuracy of the pattern is reduced due to the effects of temperature fluctuations and beam drift. It is becoming increasingly difficult to control. 256
[M-bit] In order to perform drawing with high positional accuracy on a device pattern having a sub-quarter μm size and an enormous number of patterns, such as a DRAM, it is essential to suppress the exposure time.

[0003]

2. Description of the Related Art The flow of pattern data when drawing a device pattern in a conventional electron beam drawing apparatus is described below.
This will be described with reference to the flowchart shown in FIG.

A design data 101 created by a CAD (Computer Aided Design) system is inverted, scaled,
The exposure data 103 is converted into exposure data 103 by a program 201 for performing graphic processing such as shift and shift, and division processing into a main field and a subfield of the electron beam lithography apparatus. Is done.

When actually performing exposure, a disk 105 for storing pattern data in an electron beam lithography apparatus is used.
Is transferred to the buffer memory 107 and further sent to the pattern generation circuit for drawing. Here, the capacity of the buffer memory 107 is usually about 10 million patterns.

When exposing a highly integrated device such as a 16 [M bit] DRAM or a 64 [M bit] DRAM, the number of exposure patterns for one chip may exceed the capacity of the buffer memory 107. In such a case, data transfer from the disk 105 to the buffer memory 107 is performed in units of data for one main field, and data transfer and exposure are performed alternately.

At this time, when the ith (i = 1 to M) field is to be transferred to the buffer memory 107,
The computer in the electron beam writing apparatus searches for the i-th field data from the beginning of the exposure data 103 to be exposed, and then performs the processing.

That is, as shown in FIG. 7, when the computer issues an exposure command, the i-th field data in the exposure data 105 in the disk 105 is searched (step S212) and transferred to the buffer memory 105. (Step S213), and after exposure (step S214), the search, transfer, and exposure are repeated for the (i + 1) th field data. Therefore, as the value of i increases, the interval between the end of the transfer and the start of the exposure increases.

Further, the position accuracy of the electron beam lithography apparatus, that is, the requirement for the accuracy of connection between the main field and the subfield becomes more and more severe as the device line width becomes smaller, and the field size must be set smaller for both the main field and the subfield. It is in a situation that can not be obtained. For example, the main field size is 1 [mm] or less, the subfield size is 50 [μm] or less, and the like. In addition, before, the main field size = 5 [mm],
Even with the subfield size = 100 [μm], the requirement for the positional accuracy was satisfied.

Conversely, even if the device is highly integrated, the chip size itself does not decrease, and as a result, the total number M of main fields tends to increase. For example, when a device pattern having a chip size of 10 × 20 [mm] is directly drawn with a field size of 1 [mm], the number of fields is 200.

FIG. 8 shows an example showing the above-mentioned phenomenon.
In FIG. 8, the horizontal axis is the field number i (i = 1 to M) in the disk 105, and the vertical axis is the end of the transfer of the data of the (i-1) -th field from the disk 105 to the buffer memory 107. Shows the time required for During this time, no drawing operation is performed. That is,
The exposure data 103 in the disk 105 is stored in the order of the field number and is read out sequentially, so that the time required for transfer increases in proportion to the number of field numbers.

Focusing only on this problem, the following method can be considered to suppress the increase in the total exposure time including the data transfer time. That is, as shown in FIG. 9, a plurality of design data 101 'and 10'
1 ", each of which is subjected to data conversion in the same manner as in the processing flow of FIG. 6 to obtain exposure data 103 'and 103".
And performing exposure. With this method, it has been confirmed that the processing that required 180 [minutes] as the total exposure time due to exceeding the capacity of the buffer memory 107, for example, can be reduced to 10 [minutes] by being divided into two.

However, the use of this technique causes the following problem. That is, as mentioned above,
In the data conversion processing, figure processing (2
01) and the proximity effect correction process (203) are necessary, and in that case, the connection information of the pattern is important.

The design data 101 of the device pattern exceeding the capacity of the buffer memory 107 is stored in FIG.
As shown in (1), two design data 101 ′ and 1
When the conversion processing 201 and 203 are performed by dividing the image data into 01 ", there is no information that the graphic pattern 301 is a graphic that extends over both of the divided design data 101 'and 101". When the data 103 ′ and 103 ″ are viewed together, as a result of performing the negative dimension shift processing as shown in FIG. 10B, the graphics 301 ′ and 301 ″ may be separated from each other, or as shown in FIG. As a result of the positive dimension shift as shown in FIG.
01 "may become double exposure data. In the proximity effect correction processing (203), correct correction is not performed because there is no connection information.

[0015]

As described above, in the conventional electron beam writing method and apparatus, when handling device pattern data exceeding the capacity of the buffer memory, the design data is required to increase the processing time. Is divided into a plurality of design data and subjected to graphic processing and proximity effect correction processing to generate exposure data.In this case, when the final plurality of exposure data are There has been a problem that pattern separation and double exposure data are generated. Further, there is also a problem that correct correction is not performed in the proximity effect correction processing because the connection information is not provided.

The present invention solves the above problems,
Even when handling device pattern data that exceeds the capacity of the buffer memory, it is necessary to prevent the separation of graphic patterns and the occurrence of double exposure data without lowering the throughput, and to correctly perform the proximity effect correction processing. an object of the present invention is to provide an electronic beam drawing how.

[0017]

In order to solve the above problems SUMMARY OF THE INVENTION The first electron beam drawing how the features of the present invention, FIG. 1
As shown in, exposure data off which is either et raw formed design data 1
Using an electron beam lithography system that performs file- based exposure
An electron beam lithography method to be executed , wherein predetermined conversion processes 11 and 13 are performed on the design data 1 ,
Generation step for generating exposure data for each field of
And the field in the generated exposure data
The capacity of data obtained by sequentially adding the number of patterns in
Buffer memory provided in the electron beam writing apparatus
7 determines whether a capacity less, the buffer memory
Within the capacity of the Li 7 plurality of said exposure data file 5
1 to 5-n (n is an arbitrary positive integer) to process it has an output step of outputting by dividing into the.

According to a second aspect of the present invention, there is provided an electron beam writing method according to the first aspect.
Dividing the exposure data in the output step
Is performed in units of the main field of the exposure data.
Will be

An electron beam writing method according to a third feature of the present invention.
Ekata method, the electron beam drawing Ekata <br/> method according to claim 1 or 2, the division processing of the definitive exposure data before Kide force steps, performed subfields said exposure data as a unit It is.

An electron beam writing method according to a fourth aspect of the present invention.
Ekata method, the electron beam drawing Ekata <br/> method according to claim 2 or 3, division processing of the exposure data definitive before Kide force steps is the number mainfield of the exposure data Predetermined
Only performed if the value is exceeded .

[0021]

[0022]

[0023]

The electron beam drawing <br/> how the first and second aspects of the present invention, as shown in FIG. 1, in the production step, a predetermined conversion process with respect to the design data 1 (e.g., graphics processing 1
Subjected to 1 and proximity correction process 13, etc.), a plurality of fields
Exposure data is generated for each code. Then, the output step
In the field of the generated exposure data
The capacity of the data obtained by sequentially adding the number of patterns, electronic
Capacity of buffer memory 7 provided in beam drawing apparatus
To determine a whether or less, the capacity of the buffer memory 7 or more
The output is divided into a plurality of lower exposure data files 5-1 to 5-n, and exposure is performed based on the exposure data files .

[0024] Particularly, the electron beam drawing how the second aspect of the present invention, Oite to the output steps, the division processing of the exposure data is to perform the main field of exposure data as a unit. That is, the number of patterns in the main field is sequentially added from the first main field based on the pattern information in units of the main field of the exposure data 3, and the pattern data up to the i-th main field is added. When the calculated data capacity exceeds the capacity of the buffer memory 7, the pattern data of the (i-1) th main field is output as one exposure data file 5-1. This is repeated until the M-th (M is the number of all main fields) main field, and exposure data files 5-2,..., 5-n are output.

Therefore, according to the present invention, since the exposure is performed by dividing the exposure data into a plurality of exposure data files 5-1 to 5-n, the processing time of the exposure can be shortened. That is, the exposure data 3 which has been subjected to the graphic processing 11 such as the dimension shift and the proximity effect correction processing 13
, The connection information of the pattern important in the graphic processing 11 and the proximity effect correction processing 13 is stored, and the pattern separation and double exposure data are not generated unlike the related art. And proximity effect correction processing 1
3, correct correction can be performed.

[0026] In the third electron-beam drawing how the features of the present invention, the division processing of the exposure data definitive on the outlet Chikarasu Te' flop, and to perform the subfield of the exposure data as a unit. That is, in the process of leaving Chikarasu Te' flop definitive electron beam drawing how the second aspect, in the case where the capacity of the data calculated from the pattern data up to the i-th main field exceeds the capacity of the buffer memory 7 Further, in the i-th main field, based on the pattern information in units of sub-fields, the number of patterns in the sub-field is sequentially increased from the first sub-field to the (i-1) -th main field. When the amount of data calculated based on the total exceeds the capacity of the buffer memory 7,
The pattern data of the (i-1) th main field and the (j-1) th subfield in the i-th main field are stored in one exposure data file 5-
Output as 1. This is repeated until the M-th main field, and the exposure data files 5-2,.
n is output.

Therefore, according to the processing method of this embodiment, the buffer memory 7 stores only the exposure data for the main field.
It is possible to easily cope with future ultra-high-density devices which will exceed the capacity.

Further, an electron beam writing method according to a fourth aspect of the present invention.
In Ekata method, when the electron beam drawing Ekata method of the second and third features, the division processing of the exposure data definitive on the outlet Chikarasu Te' flop, the number of main field of the exposure data exceeds a predetermined value and to carry out only to.

As described in the background art, the prolongation of the total exposure time becomes remarkable when the number of fields is large. When the total number of fields is not extremely large, the capacity of the buffer memory 7 is taken into consideration. There is no need to make a split.

[0030]

Next, an embodiment according to the present invention will be described with reference to the drawings. First Embodiment FIG. 1 is a view for explaining the flow of pattern data in an electron beam writing apparatus according to a first embodiment of the present invention.

The design data 1 created by the CAD system 200 is subjected to graphic processing such as inversion, enlargement / reduction, and shift,
The data is converted into exposure data 3 by a graphic processing program 11 that divides the data into main fields and subfields of the electron beam lithography apparatus. If necessary, the exposure data 3 is corrected by a proximity effect correction program 13.

Next, the exposure data output routine 15 divides the obtained exposure data 3 into a plurality of exposure data files 5-1 to 5-n having a capacity not larger than the capacity of the buffer memory 7 provided in the electron beam writing apparatus. Output.

This exposure data output routine 15 corresponds to FIG.
Are processed according to the flowchart shown in FIG. Note that the electron beam writing apparatus has M main fields. That is, the exposure data 3 is fetched (step S3
1) After initializing the parameters (step S32),
The number of patterns in the main field is sequentially added from the first main field based on the pattern information in units of the main field of the exposure data 3 (step S34), and the pattern up to the i-th main field is added. If the capacity of the data calculated from the data exceeds the capacity of the buffer memory 7 (step S35), the (i-1) -th
The pattern data of the first main field is output as one exposure data file 5-1 (Step S)
36). This is repeated up to the M-th main field (determined in step S33), and the exposure data file 5
−2,..., 5-n (steps S36 and S3)
9). For example, two exposure data files 5-1 and 5
In the case of dividing into -2, it becomes as shown in FIG.

The above processing is generally performed using a large-sized computer. When actual exposure is performed, for example, an exposure data file 5-1 stored on a magnetic tape or the like is used.
To 5-n are buffer memories 7 in the electron beam writing apparatus.
And then sent to the pattern generation circuit for drawing. Generally, a computer provided in an electron beam lithography apparatus is a small and medium-sized computer.
Is large enough to handle about 10 million pattern data.

At the time of exposure, an exposure data file 5-
Data transfer from 1 to 5-n to the buffer memory 7 is performed, for example, in units of data of one main field, and data transfer and exposure are performed alternately.

As described above, in this embodiment, since the exposure is performed by dividing the exposure data into a plurality of exposure data files 5-1 to 5-n, the exposure processing time can be shortened. Moreover, since the data conversion processing for the design data 1, that is, the division processing is performed on the exposure data 3 that has been subjected to the graphic processing 11 such as the size shift and the proximity effect correction processing 13, the graphic processing 11 and the proximity effect correction processing 13 The connection information of the pattern which is important for the first time is stored, so that correct correction can be performed in the proximity effect correction processing 13 without generating pattern separation or double exposure data as in the related art. Second Embodiment In this embodiment, as in the first embodiment, the flow of pattern data is as shown in FIG. This embodiment is the first
The difference from the embodiment is the processing in the exposure data output routine 15.

FIG. 4 shows a flowchart of an exposure data output routine in the electron beam writing apparatus according to the second embodiment. Note that the electron beam writing apparatus has M main fields and P subfields.

In the same manner as in the first embodiment, the exposure data 3 is fetched (step S51), parameters are initialized (step S52), and then the main data is obtained based on the pattern information in units of the main field of the exposure data 3. The number of patterns in the field is sequentially added from the first main field (step S54).

If the data capacity calculated from the pattern data up to the i-th main field exceeds the capacity of the buffer memory 7 (step S55), furthermore,
In the i-th main field, the number of patterns in the sub-field is sequentially increased from the first sub-field based on the pattern information in units of sub-fields.
It is added to the total number of patterns up to the first main field (Sh-1) (step S57).

If the data capacity calculated based on the sum (Sg) exceeds the capacity of the buffer memory 7 (step S58), the j-th main field and the j-th main field in the i-th main field are used. The pattern data of the subfields up to the first subfield is output as one exposure data file 5-1 (step S60).
This is repeated up to the M-th main field (determined in step S53), and the exposure data file 5-2,
, 5-n are output (steps S60 and S63).

In step S60, the (j-1) th subfield is output to the exposure data file 5-1 as the ith main field, and the remaining jth to Pth subfields are output. Is output as the first main field of the next exposure data file 5-2. That is, in the processing method of the present embodiment, the i-th main field of the exposure data file 5-1 and the first main field of the exposure data file 5-2 overlap.

According to the processing method of this embodiment, the future 64
[M bit] It is also possible to easily cope with a case where the capacity of the buffer memory 7 may exceed the capacity of the buffer memory 7 only by exposure data for the main field, as in an ultra-high density device after the DRAM. In other words, in the conventional electron beam writing apparatus, in such a case, the disk 10
5 cannot be transferred to the buffer memory 107, and it is necessary to reduce the field size and convert the data again. In this embodiment, the main field is automatically divided and processed. Third Embodiment In this embodiment, as in the first embodiment, the flow of pattern data is as shown in FIG. This embodiment is the first
The difference from the embodiment is the processing in the exposure data output routine 15.

FIG. 5 shows a flowchart of an exposure data output routine in the electron beam writing apparatus according to the third embodiment. As in the first embodiment, the exposure data 3 is fetched (step S31), and the parameters are initialized (step S31).
32) Next, when the number M of main fields is smaller than the predetermined value α (determined in step S71), the division processing in the first embodiment (steps S32 to S39).
Is performed, an output process (step S72) is performed.

That is, as described in the prior art (see FIG. 8), the lengthening of the total exposure time becomes remarkable when the number of fields is large. For example, when the total number of fields is several, Even if writing is performed in the same manner as in the related art, the writing time does not extremely increase. Therefore, in the flowchart of the exposure data output routine 15 of the first embodiment, step S31 is performed between step S31 and step S32.
This embodiment adds the processes of S71 and S72.

The output processing in step S72 is to collectively output one exposure data file 5-1 or, if the total number of fields is not extremely large (for example, about ten), several exposure data files 5-1. (Eg, two or four) main fields are output as one exposure data file. In this case, the capacity of each exposure data file may exceed the capacity of the buffer memory 7.

The addition of steps S71 and S72 is as follows.
This may be performed for the second embodiment, and may be inserted between steps S51 and S52 in the flowchart of FIG.

[0047]

As described above, according to the present invention,
A predetermined conversion process (for example, a graphic process or a proximity effect correction process) is performed on the design data, and the
Generate optical data and generate a filter
Of data obtained by sequentially adding the number of patterns in the
Buffer memory amount is provided in the electron beam lithography system
It is determined whether or less Li capacity, the buffer memory
And outputs the divided into the following plurality of exposure data file capacity, so it was decided to perform the exposure based on the exposure data file, processing time of the exposure by performing exposure by dividing into a plurality of exposure data file Data processing for design data, that is, division processing is performed on exposure data that has been subjected to graphic processing such as dimensional shift and proximity effect correction processing, so that graphic processing and proximity effect correction processing can be performed. The connection information of the pattern which is important at the time is stored, without generating pattern separation or double exposure data, and also in the proximity effect correction processing, an electron beam writing method capable of performing correct correction and An apparatus can be provided.

Further, according to the present invention, the division processing of the exposure data in the output Chikarasu step, so it was decided to perform the main field and or subfields the exposure data as a unit, only the exposure data in the main field of it is possible to provide an electron beam drawing how also can easily cope with buffer memory would exceed the Li capacity of future ultra-high density devices.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a flow of pattern data in an electron beam writing apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart of an exposure data output routine in the first embodiment.

FIG. 3 is an explanatory diagram in the case where exposure data is divided into two exposure data files. FIG. 3A shows the contents of the exposure data, and FIG. 3B shows the contents of the exposure data file.

FIG. 4 is a flowchart of an exposure data output routine in a second embodiment.

FIG. 5 is a flowchart of an exposure data output routine in a third embodiment.

FIG. 6 is a diagram illustrating the flow of pattern data in a conventional electron beam writing apparatus.

FIG. 7 is a flowchart of an exposure process in a conventional electron beam drawing apparatus.

FIG. 8 is a characteristic diagram illustrating the time required to transfer the i-th (i = 1 to M) field data in the disk.

FIG. 9 is a diagram illustrating a flow of pattern data in a conventional electron beam lithography apparatus that divides design data.

FIG. 10 is an explanatory diagram of pattern data in a conventional electron beam drawing apparatus that divides design data.
0 (1) is the division of the design data, FIG. 10 (2) is the exposure data with a negative dimension shift, and FIG. 10 (3) is the exposure data with a positive dimension shift.

[Explanation of symbols]

1, 101 design data 101 ′, 101 ″ divided design data 3, 103 exposure data 103 ′, 103 ″ divided exposure data 5-1 to 5-n exposure data files 105, 105 ′, 105 "disk 7, 107 buffer memory 11, 201 figure processing program 13, 203 proximity effect correction program 15 output means, exposure data output routine (output step) 17, 205 exposure processing program 200 CAD system 301 ... Figure patterns 301 'and 301 "... Divided figure patterns

Claims (4)

(57) [Claims] [Claim 1] are raw consists of design data exposure data off
Using an electron beam lithography system that performs file- based exposure
An electron beam drawing method executed performs a predetermined conversion processing for the design data, a plurality of
A generation step of generating exposure data for each field, in the field in the generated exposure data
Volume of data obtained by sequentially adding the number of patterns, the
The capacity of the buffer memory provided in the electron beam lithography system
Determining whether a quantity less, contents of the buffer memory
Electron beam drawing method and having an output step of outputting by dividing into the following plurality of said exposure data file amounts, the. 2. The method according to claim 1, wherein said exposure data in said output step is
The division processing is performed using the main field of the exposure data as a unit.
2. The electron beam writing method according to claim 1, wherein the method is performed. Division processing of 3. A definitive before Kide force steps exposure data, electron beam drawing Ekata method according to claim 1 or 2, characterized in that performed subfields said exposure data as a unit . Division processing of wherein exposure data definitive before Kide force steps a predetermined number mainfield of the exposure data
Electron beam drawing Ekata method according only be done to claim 2 or 3, characterized in the case of exceeding the value.