JP2001244181A - Electron beam lithographic data processing method, storage medium storing lithographic data processing program, and electron beam lithography system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which the type and coefficient of an irradia tion position correction formula, which can be used in an irradiation position correction function are highly dependent on a hard ware and cannot be easily modified. SOLUTION: EB lithographic data 2 are formed at an EB lithographic data forming WS 1. The drawing data correction program 6 of an EB lithographic device 5 corrects the read EB lithographic data 2 on an irradiation position on the basis of the content of a predetermined irradiation correction condition. The corrected EB lithographic data are stored in a pattern memory 8 through a transfer program 7. In a lithographic operation, generally various adjustment/ correction operations are performed for the EB lithographic system 5, and then the EB lithographic data (pattern) stored in the pattern memory 8 are drawn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam drawing data processing method for processing data for correcting an irradiation position in produced electron beam drawing data, a recording medium storing the electron beam drawing data processing program, The present invention also relates to an electron beam drawing apparatus that draws using processed electron beam drawing data.

[0002]

2. Description of the Related Art In recent years, high pattern arrangement accuracy has been required for drawing a pattern of a super-resolution photomask or an X-ray mask of the same magnification type using an electron beam exposure apparatus, or for direct drawing of an electron beam. . In general, the pattern position coordinates of a photomask or an X-ray mask are measured using an optical interference pattern coordinate measuring device or the like, and the amount of deviation from a desired position is quantified.

The desired position at this time is a design coordinate position,
For example, the lower layer pattern position. The reason why the pattern position coordinates must be controlled with high precision is that the superposition precision of each layer is very important in manufacturing a semiconductor integrated circuit. Therefore, it is important to form a pattern of a target layer with a high positional accuracy on a pattern of a base layer even in the case of pattern drawing or direct electron beam drawing for manufacturing a mask.

In a photostepper used in optical lithography, aberration characteristics are different for each stepper. The aberration is a deviation from an ideal value of a shape or a position of a beam formed or deflected by an optical system. Optical distortion. Due to different aberration characteristics, even if a photomask in which a pattern is arranged at an ideal position is used, if the stepper used for exposure is different, the position of the transferred pattern is different.

[0005] In order to manufacture an integrated circuit, several times to two
About 0 lithography steps are required. Therefore, not only does the positional accuracy of the photomask of each layer directly affect the overlay accuracy, but also the amount by which the pattern position changes due to the aberration characteristics of the photostepper used greatly affects the overlay accuracy.

[0006] If all photolithography steps can be processed using the same photostepper to fabricate one integrated circuit, the effect of aberration characteristics of each photostepper on overlay accuracy can be excluded to some extent. it can. However, it is actually difficult to manufacture an integrated circuit using the same photostepper, and an integrated circuit is manufactured using different photosteppers. In the prior art, the effect of the aberration characteristics between the photosteppers on the overlay accuracy is ignored.

The X-ray mask used in the 1-magnification projection type X-ray exposure method requires a stricter pattern position accuracy than that required for a photomask. However, since an absorber pattern made of a heavy metal that absorbs X-rays is formed on a membrane as thin as about 2 μm, there are many factors that lower the pattern position accuracy. Deformation of the substrate when holding the substrate in the electron beam lithography process, stress change of the absorber in the etching process, in-plane uniformity and average stress of the stress during film formation, average stress of the thin film used as the etching mask The in-plane uniformity of stress, the in-chip uniformity of the absorber removal area, and the like. All of these factors affect the pattern position accuracy of the X-ray mask.

FIG. 5 shows the amount of pattern position displacement that must be corrected in the process of manufacturing an X-ray mask. 31 is the position of an ideal grid point (point where thin lines cross), and 32 is the position of a grid point (point where thick lines cross) that needs correction. In the manufacturing process of the X-ray mask, pattern position displacement occurs due to partial removal of the absorber having a finite stress value due to the non-uniform distribution of the pattern area ratio in the chip. When the pattern area is extremely non-uniform, the pattern position displacement occurs in the mask manufacturing process.

Regarding the manufacture of an X-ray mask, a correction method for improving the positional accuracy by correcting a pattern position displacement generated during a manufacturing process during electron beam drawing has been proposed and put to practical use. In this correction method, an irradiation position correction function implemented in hardware of the electron beam drawing apparatus is used.
In the irradiation position correction function, the irradiation position is corrected using a correction formula in which power terms of x / y coordinates are linearly combined. The maximum order of the correction formula is the third order. To use the correction function, the coefficient of each term of the correction formula is calculated in advance, and the value is stored in a predetermined recording medium area of hardware (for example, a board) before drawing. Need to be stored.

In the electron beam direct writing method as well, in order to improve the overlay accuracy with the underlayer, the pattern position included in the underlayer is measured with an electron beam, and the predetermined pattern position of the layer to be drawn and the measured pattern position are measured. In consideration of the relative displacement of the position, the chip image of the layer to be drawn is deformed and drawn. Also in this case, the irradiation position is corrected by using a correction formula that is linearly combined with the power of the x / y coordinates, which is implemented in the hardware of the electron beam drawing apparatus. The highest order of the correction formula is generally the third order.

Regardless of whether a photomask or an X-ray mask is manufactured, or when direct writing is performed using an electron beam, an electron beam writing apparatus is used for pattern formation, and x / y coordinates are used to correct the irradiation position. A correction formula is used in which the terms of the power of are linearly combined. The maximum order of the correction equation depends on the hardware specifications of the electron beam lithography apparatus. Generally, the highest order of the correction formula is the third order, and in the case of direct drawing, the terms used for correction can be set arbitrarily, and not all terms are necessarily used.

FIG. 6 shows an irradiation position correction formula obtained by linearly combining the power of the x / y coordinates with the pattern position displacement amount which must be corrected in the manufacturing process of the X-ray mask shown in FIG. Indicates the uncorrected position when the irradiation position is corrected using the coefficient of the third-order correction formula with the highest order. Reference numeral 31 denotes the position of an ideal lattice point (point where thin lines intersect), and reference numeral 33 denotes the position of a lattice point (point where thick lines intersect) in the cubic correction formula, which indicates the remaining correction. If the amount of deviation from the ideal pattern position is defined as a triple value (3σ value) of the standard deviation calculated using the amount of deviation as a population, (146, 168) and (80) before and after correction, respectively. , 79). This value is not allowed as a correction residue. That is, the irradiation position correction function limited by the conventional hardware specifications cannot achieve the required X-ray mask position accuracy.

In either case of producing a photomask / X-ray mask or direct drawing of an electron beam, in order to improve the overlay accuracy, an irradiation position correction function limited by hardware specifications is used. . When fabricating an actual mask or drawing directly on a distorted underlayer, x
In the form of the irradiation position correction formula in which the power terms of the / y coordinate are linearly combined, the correction accuracy may not be able to achieve the required accuracy because the correction residual is too large. In such a case, the required accuracy can often be satisfied by changing the correction expression so that it can handle the highest order to a higher order, or by changing the correction expression to a correction expression obtained by linearly combining other functions. .

FIG. 7 shows a correction residue when the irradiation position is corrected using the coefficient of the correction expression of the seventh order in the form of an irradiation position correction formula in which power terms of the x / y coordinates are linearly combined. Is shown. 31 is an ideal grid point (point where thin lines intersect)
Is the position of the lattice point (the point where the thick line intersects) in the seventh-order correction formula, and indicates the remaining correction. It can be seen that the remaining correction is (43, 30), which is clearly improved. In order to improve the position accuracy of the X-ray mask by further reducing the remaining correction, a correction formula that can more accurately approximate the pattern position displacement may be determined, and the irradiation position may be corrected based on the correction formula.

FIG. 8 shows a drawing apparatus control WS which is an irradiation position control system constituted by hardware in a conventional example. Under the control of the CPU 41, the EB drawing data read from the HDD 48 is stored in the pattern memory 42, and the data read from the pattern memory 42 is controlled by the data control unit 43 and controlled by the sub deflection control circuit 44. The data is converted by the sub-deflection DAC 45 and output. On the other hand, the main deflection control circuit 46 inputs data from the data control unit 43 under the control of the CPU 41, outputs the controlled data to the sub deflection control circuit 44 and the main deflection DAC 47, and converts the data by the main deflection DAC 47. Is output.

[0016]

As described above, the form of the irradiation position correction formula which can be used in the conventional irradiation position correction function is as follows.
There is a problem that it depends heavily on hardware and cannot be easily changed for each mask / integrated circuit to be manufactured.
That is, the electromagnetic gun, the electron optical system barrel, the stage, the data control system, the (amplifier, the DAC circuit), the deflector, and the like constituting the drawing apparatus are hardware, but the irradiation position is set on dedicated hardware (for example, a board). The circuit constituting the correction function is incorporated and used so that it cannot be changed by a program.

The present invention has been made in view of the above points, and has as its object to provide an electron beam drawing data processing method capable of easily changing the form of an irradiation position correction formula usable in the irradiation position correction function. I do. Another object of the present invention is to provide a recording medium on which the electron beam drawing data processing program is recorded, and an electron beam drawing apparatus for drawing using the processed electron beam drawing data.

[0018]

SUMMARY OF THE INVENTION The amount of deviation from the ideal pattern position cannot be tolerated when the irradiation position is corrected using a correction formula of the highest order of three. When this is corrected by a drawing data correction program in the form of an irradiation position correction formula in which power terms of x / y coordinates are linearly combined, using the coefficient of the correction expression having the highest order of 7th order, the irradiation position is corrected by ( 43, 30). In order to further improve the positional accuracy of the X-ray mask by reducing the remaining amount of correction, a correction formula that can more accurately approximate the pattern position displacement is determined, and the irradiation position is determined based on the correction formula by a writing data correction program. What is necessary is just to be able to correct it.

The procedure for actually drawing from the EB drawing data by the EB drawing apparatus is as follows. The EB drawing data created by the computer system is transferred to EB drawing data storage hardware called a pattern memory of the EB drawing apparatus. Thereafter, the data is transferred to hardware for processing the stage movement amount calculation, deflection amount calculation, shot resolution, exposure time calculation, and the like.

The irradiation position correction function corrects the irradiation position by changing the deflection amount in the final stage. The irradiation position of the EB drawing data (pattern) produced by the computer system is corrected by a drawing data correction program of the EB drawing apparatus. The corrected EB drawing data is transferred to the pattern memory of the EB drawing apparatus by a drawing data transfer program. Therefore, the irradiation position correction function of the drawing data correction program makes it possible to read the format of the irradiation position correction formula and a group of parameters necessary for setting the correction amount and perform processing by software. The simplicity of complication / change can be improved.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to solve the above problems, an electron beam drawing data processing method according to the present invention provides a pattern arrangement error amount in an electron beam drawing process, a pattern position displacement amount in a mask manufacturing process, an integrated circuit manufacturing process. The amount of deformation of the substrate in the process, the amount of displacement of the lower circuit element pattern, and the like are quantified in advance, the amount of error that is the total amount of displacement from the desired position is quantified, and the error is determined using a predetermined function. Calculate the coefficient in the function that minimizes the error when the amount is approximated, and use this function to correct the irradiation position in the electron beam drawing process so that the error amount can be compensated to improve the pattern placement accuracy In the electron beam drawing data processing method, when transferring the EB drawing data used in the electron beam drawing process into the EB drawing device,
Reading the data from the recording medium of the EB drawing data, correcting the irradiation position of the read EB drawing data using a preset irradiation position correction condition,
And writing the corrected EB drawing data to a pattern memory which is predetermined hardware of the EB drawing apparatus.

The method for processing electron beam lithography data of the present invention comprises the steps of: when transferring EB lithography data to be used in the electron beam lithography step into the EB lithography apparatus, reading the data from a recording medium for EB lithography data; Correcting the irradiation position of the read EB drawing data using a preset irradiation position correction condition;
It is characterized by comprising a step of storing data in a storage device outside the drawing device, a process of reading data from the storage device, and a process of writing the read EB drawing data to a pattern memory which is predetermined hardware of the EB drawing device. Have.

Further, the recording medium storing the drawing data processing program of the present invention is a computer-readable recording medium storing the drawing data processing program,
The drawing data processing program reads EB drawing data created by an EB drawing data creation WS including a computer system from a recording medium, and corrects an irradiation position of the read EB drawing data based on an irradiation position correction condition. It is characterized by comprising a program and a drawing data transfer program for writing corrected EB drawing data to the pattern memory.

Further, the electron beam lithography apparatus of the present invention comprises: a recording medium storing a drawing data correction program; a recording medium storing irradiation position correction conditions; a recording medium storing a drawing data transfer program; A pattern memory for storing drawing data and a CPU for controlling the entire apparatus are configured as components, and EB drawing data created by the EB drawing data creation WS is recorded in an irradiation position correction condition file by software stored in a recording medium. The irradiation position is corrected using the format of the irradiation position correction formula and the coefficient of the correction formula.

[0025]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a flow of drawing data for explaining an electron beam drawing data processing method in the first embodiment of the present invention. An example will be described in which a process distortion at the time of manufacturing an X-ray mask is corrected in an electronic drawing process.

EB drawing data preparation WS1 prepares EB drawing data 2. The drawing data correction program 6 of the EB drawing device 5 corrects the irradiation position of the read EB drawing data 2 based on the contents of the preset irradiation correction condition 9. The corrected EB drawing data is stored in the pattern memory 8 by the drawing data transfer program 7.
At the time of drawing, generally, after performing various adjustment / calibration operations of the EB drawing device 5, EB drawing data stored in the pattern memory 8 is drawn. The EB drawing device 5 receives a target E from a predetermined storage device group by a drawing command.
The B drawing data is searched, and information such as a medium, a hierarchical name, and a file name in which the EB drawing data is stored is transmitted to the drawing transfer program.

That is, the drawing data correction program 6
Is a preset irradiation position correction condition (file)
The coefficient itself of the correction formula is read from 9. Next, the EB drawing data 2 is read, and the pattern position in the read EB drawing data 2 is corrected using a preset irradiation position correction formula type and a correction formula coefficient. The corrected EB drawing data is written to the pattern memory 8 in the EB drawing device 5. After that, the pattern data is transferred from the pattern memory 8 to the shot control circuit unit through the high-speed pipeline and drawn.

When transferring the EB drawing data 2 into the EB drawing apparatus 5, the irradiation position is corrected and then the pattern memory 8
Therefore, the irradiation position correction accuracy can be more easily improved as compared with the case where the irradiation position correction function is realized by hardware. In the case of the present invention, it is easy to correct the irradiation position for each figure, and it is possible to continuously deform and correct the pattern position in the chip.

FIG. 2 shows the flow of drawing data for explaining the electron beam drawing data processing method in the second embodiment of the present invention. An example will be described in which a process distortion at the time of manufacturing an X-ray mask is corrected in an electronic drawing process. EB
The EB drawing data A11 is prepared by the drawing data preparation WS10. The drawing data correction program 12 of the EB drawing data production WS 10 includes a preset irradiation correction condition 14
The irradiation position of the read EB drawing data A11 is corrected on the basis of the contents of the above. The corrected EB drawing data is stored in a recording medium in the EB drawing data preparation WS 10 in the EB drawing data B.
13 is stored. The drawing data transfer program 17 of the EB drawing device 15 stores the EB drawing data B13 read from the recording medium in the EB drawing data production WS 10 in the pattern memory 18. Generally, after performing various adjustment / calibration operations of the drawing apparatus, the target pattern data is drawn. The EB drawing device 15 searches for a target EB drawing data from a predetermined storage device group in accordance with a drawing command, and transmits information such as a medium, a hierarchy name, and a file name in which the drawing data is stored to the drawing transfer program.

That is, the drawing data correction program 12
Reads the coefficient itself of the correction formula from the irradiation position correction condition 14 set in advance. Next, EB drawing data A1
1 and the EB drawing data A1 read using the preset irradiation position correction expression format and correction expression coefficient.
1 is corrected. The corrected EB drawing data is written to a predetermined storage device as EB drawing data B13.

Information such as a medium, a hierarchical name, and a file name in which the written new drawing data B13 is stored is transmitted to the drawing data transfer program 17. The drawing data transfer program 17 reads the EB drawing data B13,
The data is written into the pattern memory 18 in the EB drawing device 15.
Thereafter, the pattern data is transferred from the pattern memory 18 to the shot control circuit unit through the high-speed pipeline,
Is drawn.

The EB drawing data A11 is transferred to the EB drawing device 15
When transferring the data into the E, the irradiation position is corrected and then the corrected E
Since the B drawing data B13 is transferred to the pattern memory 18, the irradiation position correction accuracy can be more easily improved as compared with a case where the irradiation position correction function is realized by hardware. In the case of the present invention, it is easy to correct the irradiation position for each figure, and it is possible to continuously deform and correct the pattern position in the chip.

FIG. 3 shows an example of a drawing data correction program in a recording medium storing the drawing data processing program of the present invention. The drawing data processing program according to the present invention comprises an EB drawing data preparation W comprising a computer system.
This is a series of software for reading the EB drawing data created in S from the recording medium, correcting the irradiation position of the read EB drawing data, and writing the corrected EB drawing data to the pattern memory. [S1] Drawing data correction program 6 of EB drawing apparatus 5
Reads the setting file of the irradiation position correction condition 9, and executes S2
Proceed to. [S2] Subsequently, the drawing data correction program 6 reads the EB drawing data 2 for correcting the irradiation position, and proceeds to S3. [S3] The drawing data correction program 6 calculates the coordinates of the center of the field, and proceeds to S4. [S4] The drawing data correction program 6 calculates the subfield center coordinates in consideration of the change in the field center coordinates, and proceeds to S5. [S5] The drawing data correction program 6 calculates the pattern position by taking into account the change in the field / subfield center coordinates, and proceeds to S6. [S6] The drawing data correction program 6 passes the correction data to the drawing data transfer program 7, and the drawing data transfer program 7 writes the correction data into the pattern memory, and proceeds to S7. [S7] It is checked whether all the corrected drawing data has been processed. If not, the process returns to S2.

FIG. 4 is a schematic block diagram of an electron beam drawing apparatus according to an embodiment of the present invention. By the drawing data correction program 6 stored in the recording medium 23,
The EB drawing data 2 stored in the recording medium 22 is read. The read EB drawing data 2 is stored in the recording medium 2
The position data is corrected according to the irradiation position correction condition 9 stored in the position data 4. The corrected position data is sequentially delivered to the data transfer program.

The drawing data corrected by the drawing data transfer program 7 stored in the recording medium 25 is stored in the pattern memory 26.

[0036]

As described above, according to the present invention,
The form and maximum order of the irradiation position correction formula are not limited by the equipment, and only the form and the maximum order of the irradiation position correction formula that can be handled in the software are changed without making any changes to the device. Therefore, the irradiation position can be corrected with higher accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a flow of EB drawing data for explaining an electron beam drawing data processing method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a flow of EB drawing data for explaining an electron beam drawing data processing method according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an example of a drawing data correction program in a recording medium storing an electron beam drawing data processing program of the present invention.

FIG. 4 is a schematic block diagram of an electron beam drawing apparatus according to one embodiment of the present invention.

FIG. 5 is a diagram showing a pattern position displacement amount that needs to be corrected and is generated in a manufacturing process of an X-ray mask.

FIG. 6 is a diagram showing a correction residual when the irradiation position is corrected using a coefficient of a third-order correction formula in the form of an irradiation position correction formula in which power terms of x / y coordinates are linearly combined. is there.

FIG. 7 is a diagram showing a correction residue when the irradiation position is corrected using a coefficient of a correction expression having the seventh highest order in the form of an irradiation position correction expression in which power terms of x / y coordinates are linearly combined. is there.

FIG. 8 is a diagram showing an irradiation position control system constituted by conventional hardware.

[Explanation of symbols]

Reference Signs List 1 EB drawing data preparation WS 2 EB drawing data 5 EB drawing apparatus 6 drawing data correction program 7 drawing data transfer program 8 pattern memory 9 irradiation position correction condition 10 EB drawing data preparation WS 11 EB drawing data A 12 drawing data correction program 13 EB Drawing data B 14 Irradiation position correction condition 15 EB drawing device 17 Drawing data transfer program 18 Pattern memory 21 CPU 22 Recording medium storing EB drawing data 2 23 Recording medium storing drawing data correction program 6 24 Irradiation position A recording medium on which the correction condition 9 is stored 25 A recording medium on which the drawing data transfer program 7 is stored 26 A pattern memory for storing the corrected EB drawing data 31 An ideal grid point position 32 A grid requiring correction Point position 33 Position of grid point in cubic correction formula 34 Position of grid point in cubic correction formula 41 CPU 42 Pattern memory 43 Data control unit 44 Sub deflection control circuit 45 Sub deflection DAC 46 Main deflection control circuit 47 Main deflection DAC 48 HDD

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshifumi Watanabe 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 2H095 BA02 BA10 BB01 BB10 BB33 2H097 AA03 BB01 CA16 LA10 5F056 CA11 CB11 CC01 CD01 EA06

Claims (4)

[Claims] 1. A method of quantifying in advance a pattern arrangement error amount in an electron beam drawing process, a pattern position displacement amount in a mask making process, a substrate deformation amount in an integrated circuit making process, a displacement amount of a lower circuit element pattern, and the like. Quantify the error amount that is the total deviation amount from the desired position, calculate the coefficient in the function that minimizes the error when approximating the error amount using a predetermined function, In an electron beam lithography data processing method for correcting the irradiation position in the electron beam lithography process so as to improve the pattern arrangement accuracy so that the error amount can be compensated for using an EB (electron beam) lithography used in the electron beam lithography process A step of reading the data from the recording medium of the EB drawing data when transferring the data into the EB drawing apparatus; and a step of setting the irradiation position of the read EB drawing data to a preset irradiation position correction condition. And a step of writing the corrected EB lithography data into a pattern memory which is predetermined hardware of the EB lithography apparatus. Electron beam drawing data processing method. 2. A method for quantifying in advance a pattern arrangement error amount in an electron beam writing process, a pattern position displacement amount in a mask manufacturing process, a substrate deformation amount in an integrated circuit manufacturing process, a displacement amount of a lower circuit element pattern, and the like. Quantify the error amount that is the total deviation amount from the desired position, calculate the coefficient in the function that minimizes the error when approximating the error amount using a predetermined function, In the electron beam drawing data processing method for correcting the irradiation position in the electron beam drawing process so as to improve the pattern arrangement accuracy so that the error amount can be compensated by using the EB drawing data used in the electron beam drawing process, A step of reading the data from the recording medium of the EB drawing data when transferring the data to the apparatus, and supplementing an irradiation position of the read EB drawing data by using a preset irradiation position correction condition. A correcting step, a step of storing the corrected EB drawing data in a storage device outside the EB drawing apparatus, a step of reading data from the storage apparatus, and a step of reading the read EB drawing data into predetermined hardware of the EB drawing apparatus. A method of writing data in a pattern memory. 3. A computer-readable recording medium storing a drawing data processing program, wherein the drawing data processing program comprises an EB drawing data production WS (work) comprising a computer system.
station), a writing data correction program for reading the EB writing data from the recording medium, and correcting the irradiation position of the read EB writing data based on the irradiation position correction condition, and writing the corrected EB drawing data to the pattern memory. And a data transfer program for storing a drawing data processing program. 4. A recording medium storing a drawing data correction program, a recording medium storing irradiation position correction conditions, a recording medium storing a drawing data transfer program, a pattern memory storing final corrected drawing data, A CPU for controlling the entire apparatus, and a format of an irradiation position correction formula recorded in an irradiation position correction condition file by software stored in a recording medium, the EB drawing data produced by the EB drawing data production WS; An electron beam lithography apparatus, wherein an irradiation position is corrected using a coefficient of a correction formula.