JP2013207045A - Pattern drawing method and pattern drawing apparatus using the same - Google Patents

Abstract

To provide a pattern drawing method and a pattern drawing apparatus using the same, which can stably and accurately form a photomask pattern including a fine pattern.
In a photomask pattern drawing method, a radiation dose for drawing is corrected according to a design dimension. A pattern drawing apparatus using the pattern drawing method described above, including a drawing condition correction mechanism, wherein the drawing condition correction mechanism divides design pattern data into small sections and analyzes design dimensions and drawing density. And a correction amount processing unit for each dimension that can correct the pattern size at the time of drawing and the radiation dose at the time of drawing according to the design dimensions and the drawing density, and finally correct the radiation dose by integrating multiple correction parameters A correction amount calculation processing unit.
[Selection] Figure 1

Description

  The present invention relates to a photomask pattern drawing method and a pattern drawing apparatus.

  In a manufacturing process of a photomask used in an exposure process when forming a pattern of a semiconductor or various electronic components, a pattern forming process such as photolithography or etching is performed. When drawing and developing circuit patterns by photolithography, depending on circuit pattern drawing density, drawing device, developing device used for photomask manufacturing, combination of resist and developer used, developing conditions, etc. The pattern size may cause an error compared to the pattern on the design data before drawing. Further, the dimensional variation generated in the etching process increases as the density difference of the pattern arrangement density increases. In the above drawing process, electron beam lithography, which is performed by irradiating an electron beam instead of selective irradiation for forming a fine pattern by using light such as ultraviolet rays, is also widely used, including photolithography in a broad sense. It has become.

  It is difficult to deal with pattern dimension errors due to photolithography and dimensional fluctuations in the etching process only by improving the photolithography process and improving etching conditions. For this reason, for example, the above problem is dealt with by correcting the pattern dimension corresponding to the electron beam irradiation area at the time of drawing. Correction of pattern dimension errors due to lithography / development by photolithography is generally corrected by “proximity effect correction” and “long-distance interaction correction”, and correction of dimensional variations that occur during etching is generally performed by “loading effect correction”. The correction is performed.

  These “proximity effect correction”, “long-distance interaction correction”, and “loading effect correction” are methods for canceling the dimensional variation of the pattern generated by the process by adjusting the irradiation region of the electron beam for pattern drawing. . The adjustment of the electron beam irradiation area is predetermined by “process information” that defines a drawing apparatus, a resist, a developing apparatus, a developing condition, an etching apparatus, and an etching condition. Further, according to Patent Document 1, it is possible to divide the pattern into a region having a high pattern density and a region having a low pattern density, and perform pattern dimension correction according to the pattern density.

JP-A-7-66098

  However, in the photomask manufacturing method described in Patent Document 1, in order to increase the resolution, for example, when a photomask blank coated with a thin resist film having a film thickness of 100 nm or less is used, a fine pattern having a pattern dimension of 80 nm or less is used. With respect to the portion for forming the resist, the resist residual film after development may be reduced by 10 nm or more as compared with the portion for forming another large pattern. As a result, in the fine pattern, the resist residual film may disappear in advance during the etching process, and the fine pattern may be destroyed. This is because the resist correction according to the pattern dimension is not sufficiently corrected by the conventional correction method.

  The present invention is proposed in view of the above-mentioned problems, and the problem to be solved by the present invention is a pattern that enables a photomask pattern including a fine pattern to be stably formed with high accuracy. A drawing method and a pattern drawing apparatus using the same are provided.

  As a means for solving the above problems, the invention according to claim 1 is a pattern drawing method characterized in that, in the photomask pattern drawing method, a radiation dose for drawing is corrected according to a design dimension. Is the method.

  The invention according to claim 2 is the pattern drawing method according to claim 1, wherein the radiation is an electron beam.

  The invention according to claim 3 is characterized in that in correcting the radiation dose, a relational expression between the design dimension and the correction quantity is derived, and the radiation dose for drawing is corrected according to the relational expression. The pattern drawing method according to claim 1 or 2.

  Further, the invention according to claim 4 is based on the measurement value of the pattern dimension prepared in advance, and the pattern dimension at the time of drawing and radiation irradiation at the time of drawing so that the corrected pattern dimension is close to the design dimension. The pattern drawing method according to claim 1, wherein both the quantity and the quantity are corrected.

  The invention according to claim 5 is a pattern drawing apparatus using the pattern drawing method according to any one of claims 1 to 4, including a drawing condition correction mechanism, wherein the drawing condition correction mechanism is a design pattern. Graphic processing unit that divides data into small sections and analyzes design dimensions and drawing density, and correction amount processing unit by dimension that can correct the pattern size at the time of drawing and the radiation dose at the time of drawing according to the design dimension and the drawing density And a correction amount calculation processing unit that finally corrects the radiation dose by integrating a plurality of correction parameters.

  In the invention according to claim 6, the graphic processing unit scans the divided small sections in the vertical direction and the horizontal direction, analyzes the number of continuous adjacent times of the drawing unit and the non-drawing unit, and determines the design size and the arbitrary size. The pattern drawing apparatus according to claim 5, wherein the drawing density for each of the sections is measured.

  The invention according to claim 7 is characterized in that the graphic processing unit acquires position information of an arbitrary pattern by coordinates with the vertexes of the divided small sections as coordinates. A pattern drawing device.

  In the invention according to claim 8, the dimension-specific correction amount processing unit formulates the relationship between the pattern size at the time of drawing to be corrected and the correction amount, and according to the equation, the pattern size at the time of drawing and the radiation irradiation at the time of drawing. The pattern drawing device according to claim 5, wherein the amount is corrected.

  According to the ninth aspect of the present invention, the dimension-specific correction amount processing unit is configured so that the pattern dimension after mask fabrication is close to the design value based on the separately input pattern dimension measurement value. The pattern drawing apparatus according to claim 5, wherein the pattern dimension and the radiation dose at the time of drawing are corrected.

In the photomask pattern drawing method according to the present invention, the radiation dose for drawing is corrected according to the design dimension, so that a photomask pattern including a fine pattern can be stably formed with high accuracy.
The pattern drawing apparatus using the pattern drawing method of the present invention includes a drawing condition correction mechanism, and the drawing condition correction mechanism divides the design pattern data into small sections and analyzes the design dimensions and the drawing density. And a correction amount processing unit for each dimension that can correct the pattern size at the time of drawing and the radiation dose at the time of drawing according to the design dimensions and the drawing density, and finally correct the radiation dose by integrating multiple correction parameters And a correction amount calculation processing unit that performs the pattern writing apparatus capable of stably and highly accurately forming a photomask pattern including a fine pattern.

It is a block diagram for demonstrating the method of this invention, Comprising: An example of the drawing process using the drawing apparatus provided with the drawing condition correction mechanism is shown. It is a block diagram which shows schematic structure of the drawing condition correction | amendment mechanism which concerns on embodiment of this invention. It is a part of pattern example drawn on the photomask blank in embodiment of this invention, (a) is the schematic diagram which showed a part of pattern as it is, (b) is about the divided | segmented small division It is a schematic diagram to show, (c) is a schematic diagram which shows the coordinate display of the vertex of the external shape of a small division. It is a flowchart which shows operation | movement of the drawing condition correction mechanism which concerns on embodiment of this invention. In Example 1 and Example 2, it is an example of the test pattern used and its data. 3 is a measurement result of a photomask manufactured in Example 1 using the drawing correction of the present invention. It is a measurement result of the photomask produced in Example 2 using only the conventional drawing correction.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram for explaining the method of the present invention, and shows an example of a drawing process using a pattern drawing apparatus having a drawing condition correcting mechanism.

The present invention is a pattern drawing method for correcting a radiation dose for drawing according to a design dimension in a pattern drawing method of a photomask.
Radiation is a general term for radiation including all electromagnetic waves including ultraviolet rays and all particle beams including electron beams, and can be selectively applied to resist materials that change properties when irradiated. it can. In particular, a method of selectively irradiating an electron beam resist with an electron beam is generalized as a method of drawing a fine pattern and revealing the pattern by development in a later process. Hereinafter, an example in which the radiation is an electron beam will be described in describing the mode for carrying out the present invention.

In FIG. 1, a pattern drawing apparatus 10 draws a pattern on a resist-coated photomask blank 12 to produce a pattern-drawn photomask blank 13, and the proximity effect correction and long distance described above. It includes at least a drawing condition correction mechanism 14 that corrects the electron beam irradiation area in consideration of interaction correction and loading effect correction, and corrects the pattern dimension and electron beam irradiation amount for each pattern dimension. According to the pattern drawing method of the present invention, pattern data 15 including process information and correction information is input to the drawing condition correction mechanism 14 and processed to obtain corrected pattern data and electron beam dose information 16. The conditions for electron beam irradiation on the resist-coated photomask blanks 12 placed on the pattern drawing unit 11 are given.
Note that the photomask blanks 12 having been coated with a resist is formed by forming a metal thin film (for example, chromium (Cr)) on a transparent substrate such as quartz as a light shielding layer pattern forming layer, coating a resist layer thereon, and applying ultraviolet light. Or a material whose solubility in a developer is changed by irradiation with an electron beam. Thereafter, by developing the patterned photomask blank 13, when the positive type is used for the resist layer, the irradiation region is selectively dissolved, and the light shielding layer is selectively removed in the subsequent etching process. be able to.

  The pattern drawing unit 11 is an apparatus for manufacturing the photomask blanks 13 on which pattern drawing has been performed. The model and the number of the pattern drawing unit 11 are arbitrary, and the pattern drawing unit 11 can receive the corrected pattern data and electron beam irradiation amount information. .

Next, the internal configuration of the drawing condition correction mechanism 14 in the embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing a schematic configuration of the drawing condition correction mechanism 14 according to the embodiment of the present invention. In FIG. 2, the control unit 21 has a function of controlling data in the drawing condition correction mechanism 14. The input processing unit 22 has a function of inputting pattern data, process information, and correction information for drawing a pattern on the resist-coated photomask blanks 12.
It should be noted that the input processing unit 22 does not have any problem even if pattern data, process information, and correction information are input via a storage medium. In this case, the input processing unit 22 has a storage medium reading function, or pattern data, process information via a network. And a function of receiving correction information data.

  The storage unit 23 has a function of storing various predetermined information in order to perform correction processing of electron beam irradiation conditions for pattern drawing. The storage unit 23 stores information on predetermined conditions related to the proximity effect correction 23a, the long-range interaction correction 23b, the loading effect correction 23c, and the like indicated by a broken line frame.

The graphic processing unit 24 has a function of dividing design pattern data input from the input processing unit 22 into small sections of a predetermined shape and analyzing design dimensions and drawing density. Hereinafter, it demonstrates according to an example.
FIG. 3 is a part of a pattern example drawn on the photomask blank in the embodiment of the present invention, (a) is a schematic diagram showing a part of the pattern as it is, and (b) is a divided pattern. It is a schematic diagram shown about the made | formed small division, (c) is a schematic diagram which shows the coordinate display of the vertex of the external shape of a small division.
For example, the pattern data shown in FIG. 3A is divided into a large number of small sections as shown in FIG. Here, the region of the drawing unit 31 indicates a region to be drawn, and the region of the non-drawing unit 32 indicates a region that is not drawn. When the small section is set to a shape of 10 nm × 10 nm and divided, the divided section is scanned with the vertical direction and the horizontal direction as the scanning direction 1 and the scanning direction 2, respectively, thereby drawing unit 31 and non-drawing unit 32. Thus, the design size of 10 nm or more and the drawing density for each arbitrary region can be measured. Further, when the vertices of the outer shape of the small section are set to the coordinates shown in FIG. 3C, if the entire pattern data is divided into the small sections, it is possible to acquire information on an arbitrary pattern position with the coordinates.

  The dimension-specific correction amount processing unit 25 has a function of extracting a pattern to be corrected from the small sections divided by the graphic processing unit 24 and adjusting the electron beam irradiation amount and pattern dimensions to be drawn. For example, when the dimension correction amount of the design dimension to be corrected and the correction amount of the electron beam irradiation amount for pattern drawing are input to the input processing unit 22, the dimension correction amount and the correction amount of the electron beam irradiation amount with respect to the design dimension to be corrected Can be corrected according to actual dimensions. Further, regarding the correction amount of the electron beam irradiation amount, the correction amount processing unit 25 for each dimension formulates the relationship between the design dimension to be corrected and the correction amount to derive a relational expression, and the electron beam for drawing according to the relational expression The dose can be corrected.

  The correction amount calculation processing unit 26 uses the information regarding the proximity effect correction 23a, the long-range interaction correction 23b, and the loading effect correction 23c stored in the storage unit 23 for each pattern size calculated by the dimension-specific correction amount processing unit 25. A correction amount of the electron beam irradiation amount is added, all of the plurality of correction parameters are integrated, and the electron beam irradiation amount is finally calculated and corrected.

Each processing unit shown in FIG. 2 can be realized by dedicated hardware, and each processing unit is configured by a memory and a CPU (central processing unit) to realize the function of each processing unit. The function of each processing unit can be realized by loading a program for executing the program into the memory and executing the program.
The memory includes a nonvolatile memory such as a hard disk device, a magneto-optical disk device, and a flash memory, a recording medium such as a CD-ROM that can only be read, and a volatile memory such as a RAM (Random Access Memory). Or a combination of these and a computer-readable / writable recording medium.

  Next, the operation of the drawing condition correction mechanism 14 described above will be described. FIG. 4 is a flowchart showing the operation of the drawing condition correction mechanism 14 according to the embodiment of the present invention. First, pattern data relating to the pattern shape, dimension, positional relationship, process information relating to process conditions, and correction information as default information relating to correction are input to the input processing unit 22 (S10). Next, the graphic processing unit 24 divides the pattern data input from the input processing unit 22 into small sections shown in FIG. 3B (S11). Thereafter, the divided patterns are scanned to examine the dimensions and coordinate data of each pattern (S12).

  Next, the dimension-specific correction amount processing unit 25 determines the correction amount of the electron beam irradiation amount for drawing with the pattern dimension for each pattern dimension with respect to the pattern data in the small sections divided by the graphic processing unit 24 ( S13). Here, the correction amount of the pattern dimension is transferred to the output processing unit 27, and the correction amount of the electron beam irradiation amount is transferred to the correction amount calculation processing unit 26.

Next, in the correction amount calculation processing unit 26, the proximity effect correction 23 a, the long-range interaction correction 23 b and the loading effect correction 23 c stored in the storage unit 23, and the pattern size calculation unit 25 calculated by the dimension correction amount processing unit 25. Are added to calculate the electron beam dose with all corrections taken into account (S14).
Through the above flow, the corrected pattern data and the electron beam irradiation amount for drawing are transferred to the drawing unit (S15).

  In addition, the present invention provides a pattern size at the time of drawing and a drawing size so that the corrected pattern size is close to the design size by feeding back the correction result based on the measurement value of the pattern size prepared in advance. It is possible to correct both the radiation dose at the time. Therefore, each time the use opportunity of the present invention is increased, a pattern drawing method for forming a photomask pattern with higher accuracy and higher resolution can be provided.

  In order to carry out the above method, in the pattern drawing apparatus of the present invention, based on the measurement value of the pattern dimension separately input through the input processing unit 22, the dimension-specific correction amount processing unit 25 performs the mask fabrication. Thus, the function of correcting the pattern dimension at the time of drawing and the radiation dose at the time of drawing can be exhibited so that the pattern dimension becomes close to the design value.

  In addition to conventional corrections (proximity effect correction, long-distance interaction correction, loading correction), the drawing apparatus 10 according to the embodiment of the present invention adds corrections for pattern dimensions and electron beam doses for each pattern dimension. As a result, the film thickness of the resist after development corresponding to the pattern dimension becomes uniform, and the photomask pattern can be stably formed with high accuracy and high resolution. Examples of pattern drawing according to the present invention will be described below.

  This embodiment is one of the embodiments according to the present invention. As a result of adding the pattern size and the electron beam irradiation amount correction amount by using the pattern drawing apparatus 10 shown in FIG. This shows that the method can stably form the photomask pattern with high accuracy because the film thickness of the film becomes uniform.

Element dimensional characteristics of a photomask manufactured using conventional drawing correction (proximity effect correction, long-range interaction correction, loading effect correction) and a photomask added with dimensional correction using the drawing apparatus 10 of the present invention ( The effect of the invention was confirmed by comparing the CD characteristics) and the resist residual film after development.
The CD characteristics were evaluated by using an iso-opaque pattern in which the test pattern 41 shown in FIG. 5 was used and the design value was varied from 1000 nm to 50 nm.
The resist used in the examples of the present invention was a positive-type chemically amplified resist, and the film thickness was 100 nm.

  FIG. 6 is a measurement result of the photomask manufactured by using the drawing correction of the present invention in Example 1, from the resist residual film thickness and the measured and designed values of the line width expressed by the CD characteristics. Indicates deviation. When the drawing correction of the present invention is added to the conventional drawing correction, the film thickness of the resist remaining film is flat without being reduced to the line width design value of 50 nm. This is considered that the electron beam correction amount for each dimension was optimal. Further, the CD characteristic range (nm) was 2 nm, and the resolution limit was 50 nm as a design value.

<Comparative example>
FIG. 7 is a measurement result of the photomask manufactured using only the conventional drawing correction in Example 2, and is based on the film thickness of the residual resist film and the measured and designed values of the line width expressed by the CD characteristics. Indicates deviation. With only the conventional drawing correction, the film thickness of the resist remaining film after development is rapidly reduced from the vicinity of the design value of 70 nm of the line width. This is presumably because the finer patterns are more susceptible to fogging by electron beam irradiation. Further, the range (nm) of the CD characteristics was 9 nm, and the resolution limit was 70 nm as a design value, both of which were inferior to Example 1.

  From the above, comparing the result of drawing using the pattern drawing apparatus 10 according to the present invention with the result of drawing using only the conventional drawing correction, the present invention is less likely to reduce the remaining resist film after development. Both image properties and CD characteristics were good. Thereby, by using the drawing apparatus 10 according to the present invention, high-precision and high-resolution element dimensional characteristics can be stably realized.

DESCRIPTION OF SYMBOLS 10 ... Pattern drawing apparatus 11 ... Pattern drawing part 12 ... Photomask blanks 13 with resist application ... Photomask blanks 14 with pattern drawing ... Drawing condition correction mechanism 15 ... Pattern data (Including process information and correction information)
16 ... Pattern data after correction and electron beam irradiation information 21 ... Control unit 22 ... Input processing unit 23 ... Storage unit 23a ... Proximity effect correction 23b ... Long-range interaction correction 23c ... Loading effect correction 24 ... Graphic processing unit 25 ... Dimensional correction amount processing unit 26 ... Correction amount calculation processing unit 27 ... Output processing unit 31 ... Drawing unit 32 ... Non-drawing part 41 ... Test pattern

Claims (9)

  In the photomask pattern drawing method, the radiation exposure dose for drawing is corrected according to the design dimension.   The pattern drawing method according to claim 1, wherein the radiation is an electron beam.   3. The pattern according to claim 1, wherein in correcting the radiation dose, a relational expression between the design dimension and the correction quantity is derived, and the radiation dose for drawing is corrected according to the relational expression. Drawing method.   It is characterized by correcting both the pattern size at the time of drawing and the radiation dose at the time of drawing so that the corrected pattern size is close to the design dimension based on the measurement value of the pattern dimension prepared in advance. The pattern drawing method according to claim 1. A pattern drawing apparatus using the pattern drawing method according to claim 1, comprising a drawing condition correction mechanism, wherein the drawing condition correction mechanism comprises:
A graphic processing unit that divides design pattern data into small sections and analyzes design dimensions and drawing density;
A correction amount processing unit for each dimension that can correct the pattern size at the time of drawing and the radiation dose at the time of drawing according to the design dimension and the drawing density,
A pattern drawing apparatus comprising: a correction amount calculation processing unit that integrates a plurality of correction parameters to finally correct a radiation dose.   The graphic processing unit scans the divided small sections in the vertical and horizontal directions, analyzes the number of consecutive adjacencies between the drawing unit and the non-drawing unit, and measures the design dimensions and the drawing density for each arbitrary block. The pattern drawing apparatus according to claim 5, wherein:   The pattern drawing apparatus according to claim 5, wherein the graphic processing unit acquires position information of an arbitrary pattern by using the vertex of the divided small section as a coordinate.   A correction amount processing unit for each dimension derives a relational expression between a pattern dimension at the time of drawing to be corrected and a correction amount, and corrects the pattern dimension at the time of drawing and the radiation dose at the time of drawing according to the relational expression. The pattern drawing apparatus according to claim 5.   Based on the pattern dimension measurement value that is input separately, the dimension-specific correction amount processing unit calculates the pattern dimension at the time of drawing and the radiation dose at the time of drawing so that the pattern dimension after mask fabrication is close to the design value. The pattern drawing apparatus according to claim 5, wherein correction is performed.

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