JP2004077532A - Reticle manufacturing method and reticle manufacturing apparatus - Google Patents

Abstract

A reticle manufacturing method capable of improving the accuracy of a pattern dimension without increasing the number of steps is provided.
A chemically amplified resist film is formed on a reticle substrate, the chemically amplified resist film is prebaked, a reticle pattern is drawn on the chemically amplified resist film, and a PEB process is performed on the drawing area. The pattern density PD of the drawing region is calculated based on the drawing data of the reticle pattern, and the amount of heating of the chemically amplified resist film in the PEB process is adjusted based on the pattern density.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a reticle used in a lithography process of a semiconductor device.
[0002]
In recent years, semiconductor devices have been increasingly integrated and miniaturized, and in order to further promote the miniaturization, it is necessary to form a finer resist pattern in a lithography process. Further, in order to form a fine resist pattern, it is necessary to improve the pattern accuracy of a reticle used in a lithography process, and it is necessary to prevent an increase in the number of steps in the reticle manufacturing process. .
[0003]
[Prior art]
In recent lithography techniques, high-sensitivity resists represented by chemically amplified resists have been adopted for the purpose of improving productivity and the like. High-sensitivity resists have higher sensitivity than general resists, but undergo dramatic dimensional changes with respect to baking temperature and baking time, and high-precision baking is indispensable.
[0004]
It is also known that a dimensional change occurs depending on the time from exposure to baking, so that a dimensional error distribution depending on the elapsed time from exposure occurs on the substrate.
[0005]
For example, in a sequential exposure method such as electron beam exposure, not only the exposure time is long, but also the exposure speed can be changed depending on the pattern density, so that the dimensional variation factor is more complicated.
[0006]
Further, depending on the time from the end of the exposure to the post-exposure bake (PEB: Post Exposure Bake), it is affected by the atmosphere and the generated acid catalyst.
Reticles used in light exposure such as steppers are also manufactured using lithography technology.However, in the reticle manufacturing process, even when using a high-sensitivity resist, high-density data exposure that requires an exposure time exceeding one hour is also required. is there.
[0007]
This dimensional variation depending on the length of the exposure time is not acceptable for the demand for higher precision of the reticle pattern.
In particular, in the case of a reticle, the outer shape of the reticle is square, the thickness is several mm, and the glass is made of glass such as quartz, which has extremely poor thermal conductivity. And complicated thermal characteristics, making uniform baking of the resist film more difficult.
[0008]
Japanese Patent Application Laid-Open No. H11-194506 discloses a pattern forming method for improving the accuracy of a reticle pattern using such a high-sensitivity resist.
That is, two baking steps are performed for the purpose of uniforming the size distribution, and the dimension of the resist pattern that has been optically reacted after the first baking step including the PEB step is performed by measuring the pattern dimension between each step. Measure.
[0009]
Then, there is disclosed a method of performing baking such that in-plane nonuniformity of a dimensional error distribution is uniformed in a second baking step based on the measurement result.
[0010]
[Problems to be solved by the invention]
However, the above-described pattern forming method requires two baking steps, and thus has a problem that the number of steps increases.
[0011]
In addition, the dimension measurement of the resist pattern has a large measurement variation as compared with the dimension measurement of a light shielding film such as chrome (Cr), so that data for reliably correcting the dimension error in the second baking step can be obtained. Can not.
[0012]
Further, although the dimension measurement of the resist pattern after the first baking step can be replaced by the measurement of a sample, the number of steps cannot be prevented since two baking steps are still required.
[0013]
An object of the present invention is to provide a reticle manufacturing method capable of improving the accuracy of a pattern dimension without increasing the number of steps.
[0014]
[Means for Solving the Problems]
A reticle manufacturing method comprising: forming a chemically amplified resist film on a reticle substrate, prebaking the chemically amplified resist film, drawing a reticle pattern on the chemically amplified resist film, and performing PEB processing on the drawn region. The pattern density of the drawing area is calculated based on the pattern drawing data, and the amount of heating of the chemically amplified resist film in the PEB process is adjusted based on the pattern density.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a reticle manufacturing method and a reticle manufacturing apparatus according to an embodiment of the present invention will be described with reference to the drawings.
[0016]
As shown in FIG. 1, prior to manufacturing a reticle, the drawing data processing unit 1 generates drawing data of a reticle pattern, and the generated drawing data is stored in a drawing data file 2.
[0017]
Next, based on the drawing data stored in the drawing data file 2 and the data input from the drawing arrangement information and the conversion parameter input unit 3, image data processing is performed by the reticle image data processing unit 4, and the processing result Is stored in the density definition file 5.
[0018]
Then, the bake point control device 6 operates based on the data stored in the density definition file 5 to control the PEB device.
FIG. 2 shows the processing contents of the reticle image data processing unit 4. Subsequent to input of the drawing data from the drawing data file 2 (step 1), first, coordinate conversion of the drawing data is performed (step 2).
[0019]
The center coordinate of the drawing data is set at the lower left of each data area, but the drawing arrangement information input from the drawing arrangement information and the conversion parameter input unit 3 is set with the origin coordinates set as the center of the data area. .
[0020]
Therefore, conversion is performed so that the origin coordinates of each data area become the center of the data area so that the center coordinates of the drawing data match the center coordinates of the drawing arrangement information.
Next, all drawing data is developed into a reticle image based on the drawing arrangement information (step 3). Next, detection of an overlapping portion of the pattern is performed as a validity check in the developed drawing data (step 4), and if there is no overlapping portion, a drawing data combining process is performed (step 5). The reticle image 7 shown in FIG. 6 is generated by such a process of synthesizing the drawing data.
[0021]
Next, the reticle image 7 is divided into a number of grid regions 8 (step 6). For example, in FIG. 6, the reticle image 7 is set to an effective area of 150 mm □ based on the conversion parameters with a slight margin in the actual pattern area, and the grid area 8 is 7.5 mm □ obtained by dividing the effective area into 20 areas. Is set.
[0022]
Next, the pattern density of the divided grid area 8 is calculated (Step 7), and the density definition file 5 is generated based on the pattern density (Step 8).
The data stored in the density definition file 5 is as follows.
[0023]
Minimum pattern size: As shown in FIG. 6, the minimum width w1 of the pattern in the lattice area 8 is stored. In the example shown in FIG.
Minimum space dimension; The minimum space w2 between the patterns in the lattice area 8 is stored. In the example shown in FIG. 6, it is stored as, for example, 200 nm.
[0024]
Lower left coordinates of grid; X and Y coordinates of lower left corner C1 of the grid with respect to the origin coordinates of reticle image 7 are stored.
Upper left coordinates of the grid; X and Y coordinates of the upper left corner C2 of the grid with respect to the origin coordinates of the reticle image 7 are stored.
[0025]
Upper right coordinates of the grid; X, Y coordinates of the upper right corner C3 of the grid with respect to the origin coordinates of the reticle image 7 are stored.
Lower right coordinates of grid; X, Y coordinates of lower right corner C4 of grid with respect to origin coordinates of reticle image 7 are stored.
[0026]
Grid center coordinates: The X and Y coordinates of the center C5 of the grid with respect to the origin coordinates of the reticle image 7 are stored.
Grid area; area of each grid is stored. In the example shown in FIG. 6, a value of 56.25 mm ² is stored as the area of the grid of 7.5 mm square.
[0027]
Total pattern area in lattice; The total area of the pattern portion in the lattice area 8 is stored. In the example shown in FIG. 6, a value of 33.86 mm ² is stored.
Pattern density: The ratio of the total pattern area in the grid to the grid area is stored. As shown in FIG. 7, the pattern density distribution PD of each lattice region 8 on the reticle image 7 is such that the pattern density in the central portion is high and the pattern density in the peripheral portion is low in a normal device.
[0028]
Pattern occupancy; pattern density × 100 is calculated and stored as the pattern occupancy. In FIG. 7, the pattern occupancy of each lattice region 8 is relatively represented by the size of a circle, where the maximum pattern occupancy is 60% and the minimum pattern occupancy is 0.1%.
[0029]
FIG. 4 shows the outline of the PEB device 9. The XY stage drive circuit unit 10 controls the motor controller 11 based on a control signal output from the bake point control device 6.
[0030]
The motor controller 11 controls the X motor 12 and the Y motor 13 to move the XY stage 14 in the X direction or the Y direction.
As shown in FIG. 5, a reticle substrate 16 is mounted on an XY stage 14 via a cool plate 15, and a guide plate 19 is provided above the reticle substrate 16.
[0031]
The temperature control circuit 17 receives the position information of the XY stage from the XY stage drive circuit 10 and the temperature control information from the bake point control device 6. Then, the temperature control circuit 17 controls the temperature control controller 18 based on the input information.
[0032]
The temperature control unit 18 blows the air whose temperature is adjusted to 95 ° from the blower tube 20 onto the reticle substrate 16 in a spot shape based on a control signal output from the temperature control circuit unit 17.
[0033]
The air outlet of the air duct 20 is made of 6 mm square smaller than the lattice area in consideration of heat diffusion.
Next, the reticle manufacturing process will be described with reference to FIG. A positive resist is applied to the surface of the reticle substrate 16 (step 11), and a pre-bake process is performed by a pre-bake device (step 12).
[0034]
Next, a reticle pattern is drawn on the reticle substrate 16 by an electron beam exposure apparatus (step 13).
Next, based on the control of the bake point control device 6, the PEB device 9 performs the PEB process on the drawing area on the reticle substrate 16 (step 14). That is, the PEB process is performed for each lattice area by moving the XY stage 14 stepwise in the X direction or the Y direction.
[0035]
Then, as shown in FIG. 8, when the pattern occupation ratio of the target grid region 8 is 60%, the XY stage 14 is allowed to stay for 15 seconds, and the temperature-controlled air is blown toward the resist film surface. .
[0036]
When the pattern occupancy of the target grid region 8 is 30%, the XY stage 14 is allowed to stay for 30 seconds, and the temperature-controlled air is blown toward the resist film surface.
[0037]
In this way, the stay time of the XY stage 14 is linearly corrected based on the pattern occupancy of each lattice area 8.
Further, in addition to the above-described correction processing, a correction processing for the time from the pattern drawing in step 13 to the PEB processing is also performed. That is, the staying time of the XY stage 14 is linearly corrected with respect to the time-dependent change in the catalytic reaction of the high-sensitivity resist from pattern drawing to PEB processing.
[0038]
As shown in FIG. 9, as the elapsed time from the pattern drawing processing to the PEB processing becomes longer, the space dimension between the patterns in the lattice area 8 becomes larger. When a dimensional error of 50 nm occurs when 240 minutes have elapsed from the drawing process, an average dimensional error of 12.5 nm occurs every 60 minutes.
[0039]
Thus, in the PEB processing, linear correction is performed such that the XY stage 14 stays for 32 seconds in the grid area 8 where 240 minutes have passed since the drawing processing, and stays for 24 seconds in the grid area 8 where 60 minutes have passed.
[0040]
Next, in step 15, the resist film is developed, and post-baking, discumming, and etching are performed as in the related art to manufacture a reticle (steps 16 to 18).
[0041]
With the reticle manufacturing method as described above, the dimensional error and the dimensional error related to the position on the reticle surface of the reticle having the pattern occupancy shown in FIG. Can be reduced.
[0042]
In the reticle manufacturing method as described above, the following operation and effect can be obtained.
(1) Rather than measuring the resist pattern dimensions after the baking process with large measurement variations and correcting the subsequent baking process, the pattern density distribution is calculated based on the drawing data, and the PEB is calculated based on the pattern density distribution. It was decided to add a correction to the processing. Therefore, the PEB process for correcting the in-plane non-uniformity of the dimensional error of the resist pattern can be performed in one PEB process.
(2) A reticle in which the in-plane non-uniformity of the dimensional error of the pattern dimension is made uniform by one PEB process can be manufactured. Therefore, the number of reticle manufacturing steps is not increased.
(3) The PEB processing can be corrected for each grid region 8 based on the pattern occupancy of a large number of grid regions 8 obtained by dividing the reticle image 7. Therefore, an accurate resist pattern can be formed.
(4) The PEB process can be corrected for each grid region 8 based on the elapsed time from the drawing of the resist pattern to the PEB process. Therefore, it is possible to correct the in-plane non-uniformity of the dimensional error of the resist pattern based on the use of the high-sensitivity resist, and to form an accurate resist pattern.
(5) The PEB processing can be corrected by controlling the PEB device 9 based on the calculated pattern density distribution or pattern occupancy. Therefore, the steps other than the PEB processing step may be the same as the conventional processing, so that complicated steps need not be changed.
[0043]
The above embodiment can be modified as follows.
The resist pattern may be corrected by controlling the heating amount in the PEB process based on the heating temperature based on the pattern density information or the pattern occupancy of each lattice region 8.
[0044]
【The invention's effect】
As described in detail above, the present invention can provide a reticle manufacturing method capable of improving the accuracy of pattern dimensions without increasing the number of steps.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating a PEB processing data generation unit according to an embodiment;
FIG. 2 is a flowchart illustrating a PEB correction processing data generation step.
FIG. 3 is a flowchart illustrating a reticle manufacturing process.
FIG. 4 is a schematic diagram showing a PEB device.
FIG. 5 is a schematic diagram showing an XY stage.
FIG. 6 is an explanatory diagram showing a PEB correction processing data generation operation.
FIG. 7 is an explanatory diagram showing a pattern density distribution.
FIG. 8 is an explanatory diagram showing a correction value of a stage stay time.
FIG. 9 is an explanatory diagram showing a relationship between an elapsed time after writing and a dimensional error of a resist pattern.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 drawing data processing unit 4 reticle image data processing unit 6 bake point control device 7 reticle image 8 lattice area 9 PEB device 14 XY stage 16 reticle substrate PD pattern density

Claims (7)

A reticle manufacturing method comprising: calculating a pattern density of a reticle image; and performing a PEB process based on the pattern density. A reticle manufacturing method for forming a chemically amplified resist film on a reticle substrate, prebaking the chemically amplified resist film, drawing a reticle pattern on the chemically amplified resist film, and performing a PEB process on the drawn region,
A reticle manufacturing method, comprising: calculating a pattern density of the writing area based on the writing data of the reticle pattern; and adjusting a heating amount of the chemically amplified resist film in a PEB processing step based on the pattern density. . A reticle manufacturing method for forming a chemically amplified resist film on a reticle substrate, prebaking the chemically amplified resist film, drawing a reticle pattern on the chemically amplified resist film, and performing a PEB process on the drawn region,
The drawing data of the reticle pattern is divided into a plurality of grid areas, the pattern density of each grid area is calculated, and the amount of heating of the chemically amplified resist film in the PEB process is adjusted based on the pattern density. Reticle manufacturing method. A reticle manufacturing method for forming a chemically amplified resist film on a reticle substrate, prebaking the chemically amplified resist film, drawing a reticle pattern on the chemically amplified resist film, and performing a PEB process on the drawn region,
Dividing the drawing data of the reticle pattern into a plurality of grid regions, calculating a pattern occupancy of each grid region, and adjusting a heating amount to the chemically amplified resist film in the PEB processing step based on the pattern occupancy. A reticle manufacturing method characterized by the above-mentioned. The reticle manufacturing method according to claim 2, wherein the heating amount is adjusted by adjusting a residence time of an XY stage of a PEB apparatus. The reticle manufacturing method according to claim 2, wherein the heating amount is adjusted by adjusting a temperature of air blown toward the chemically amplified resist film in the PEB apparatus. A drawing data processing unit that generates drawing data of the reticle pattern;
A reticle image data processing unit that generates reticle image data based on the drawing data, divides the reticle image data into a plurality of grid areas, and calculates a pattern density of the grid areas;
A bake point control device for controlling the residence time of the XY stage of the PEB apparatus based on the pattern density to uniform the in-plane non-uniformity of the dimensional error of the resist pattern on the reticle substrate. Reticle manufacturing equipment.

Images