JPH10319572A - Manufacturing method of halftone phase shift mask - Google Patents

Abstract

(57) [Problem] To provide a method for manufacturing a halftone phase shift mask capable of generating a light shielding pattern of HTPSM in a practical processing time. SOLUTION: Light-shielding pattern area data and light-shielding pattern exclusion area data are extracted from layout data of a halftone phase shift mask (S12, S13), and coordinates of the transmitted light portion determined according to the light-shielding pattern area data. Is normalized and registered in the array area table (S2). Based on the shading pattern exclusion area data, a transmitted light portion in which the coordinates intersecting with the shading pattern exclusion area are registered is searched for with reference to the array area table. (S
15) For the searched transmitted light portion, the coordinates of the newly generated rectangular transmitted light portion are registered in the array region table so as to remove the portion that intersects with the light-shielding pattern exclusion region (S17). The drawing data of the light shielding pattern is generated from the table.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a halftone phase shift mask.

[0002]

2. Description of the Related Art A halftone phase shift mask (HTPSM: Half Tone) used in a manufacturing process of a semiconductor device.
Phase Shift Mask) has a property of transmitting light at a certain transmittance (the property of half transmitted light) in a portion corresponding to a light-shielding pattern area in a normal mask. The transmittance is determined as a specification of the mask, and is, for example, 4% or 8%. In the HTPSM, a 180 ° angle is provided between halftone transmitted light and light from an original transmitted light portion (hereinafter, transmitted light).
With the effect of the interference of these lights, a more precise pattern formation is aimed at. When this mask is actually used in an LSI manufacturing process, an operation for sequentially exposing is performed by step-and-repeat in the same manner as a normal mask.

At this time, in the case of a normal mask, the periphery of the exposure area is completely shielded from light, so that there is no problem of multiple exposure. As shown in FIG. 6, a double exposure portion 1 due to half transmitted light is generated between the exposed regions by step and repeat, as shown in FIG.
Further, quadruple exposure portions 2 due to the half transmitted light are generated at the corner portions of the exposure region. In such a double exposure portion 1 and a quadruple exposure portion 2, exposures twice and four times as large as those of the halftone transmitted light portion are performed, and a correct pattern cannot be formed in those portions due to unnecessary multiple exposure.

In order to solve this problem, a light-shielding pattern 10 having a fine rectangular array pattern as shown in FIG. 7 is formed in an area where multiple exposure using half transmitted light is performed, and a halftone transmitted light portion 11 is formed. A method has been proposed to minimize the problem of multiple exposure due to interference between the transmitted halftone transmitted light and the light transmitted through the rectangular transmitted light portion 12. The rectangular size of the transmitted light portion 12 of the light shielding pattern 10 and the pitch of the array pattern are determined according to the wavelength used for exposure.

[0005] From the above viewpoint, a light-shielding pattern is formed in the HTPSM. This light-shielding pattern is
Similarly to the other patterns on M, the mask is formed as data in input data (hereinafter referred to as drawing data) of a device for drawing a mask (hereinafter referred to as a drawing device) and formed by drawing in the same manner as the other patterns. Conventionally, there are the following two methods for generating a light-shielding pattern. The first method is HTP
When creating an SM mask pattern, do not arrange a pattern of marks near the area where the light-shielding pattern is to be formed, and form the light-shielding pattern in a square area that is large enough to be light-shielded. Then, as shown in FIG. 8, the drawing data corresponding to the light shielding pattern 13 is repeatedly drawn in the area to be shielded. In the example shown in FIG. 8, the light shielding pattern 13 is repeatedly drawn along the exposure pitch area 14. This is called a repetitive drawing method.

In the second method, light-shielding pattern data for forming a light-shielding pattern in the entire mask pattern and in all the light-shielding areas is generated in advance, and the area of the chip that should not be shielded from the HTPSM mask pattern is generated. Then, a pattern existing in the area of the chip to be shielded from light is checked, and graphic calculation processing for removing these is performed on the light-shielded pattern data. In the example shown in FIG. 9, first, light-shielding pattern data for forming a light-shielding pattern 15 along the exposure pitch area 14 is generated, and graphic processing for removing the light-shielding pattern exclusion area 16 from the light-shielding pattern 15 is performed. To do. This is called a graphic operation method.

[0007]

In the repetitive drawing method shown in FIG. 8, it is not necessary to substantially create a light-shielding pattern, and only an instruction on how to arrange an existing light-shielding pattern is provided. Although the amount of calculation may be reduced, a light-shielding pattern is unconditionally placed at the boundary of the repeat unit area near the boundary of the exposure pitch area 14 shown in FIG. Can not be placed. In general, marks necessary for monitoring the state of the LSI manufacturing process and for performing step-and-repeat are formed in an exposure pitch area (chip) 14.
In many cases, the marks cannot be arranged in this portion, and the inability to arrange the marks at this portion imposes great restrictions on the mask pattern design, and there is a problem that a practical mask cannot be created.

In the graphic calculation method, a light-shielding pattern graphic is once created in all the light-shielded areas including the entire exposure area on the mask. For example, at a certain exposure wavelength, a light-shielding pattern necessary to shield light is shown in FIG.
In the case of the specifications shown in the above, with a square chip of 22 mm,
When a five-fold mask is created, the size of the area to be shaded is a square of about 113.6 mm above the mask, and the number of rectangles of the shade pattern created here is about 3,98830.
It will be 100,000. The basis for calculating the number of rectangles is that the light-shielding width is 1500 μm above the mask, the one-side scribe line width is 300 μm above the mask, and the light-shielding pattern pitch is 1.8 μm above the mask.
Is expressed by the following equation (1).

(Equation 1)

When this light-shielding pattern is expressed in normal layout data, it is created hierarchically.
The number of light-shielding patterns does not matter. However, in the next step, when the work of removing the light-shielding pattern exclusion area 16 shown in FIG.
Since all 10,000 light-shielding pattern rectangles are handled, there is a problem that a very large amount of calculation is required and the processing time is too long. In this graphic operation method, a practical HTPSM mask pattern can be created by setting a light-shielding pattern exclusion area, so that a pattern can be arranged at an arbitrary position on the mask. There's a problem.

In addition to the above, the same method as the repetitive drawing method is used.
A method of generating a light-shielding pattern and removing the pattern of the exclusion area by the graphic operation processing is also conceivable. In this case, the number of figures to be processed at the time of figure calculation can be about 289 million. The number of the processed graphics is obtained by the following equation (2).
However, this method also requires several hours of processing time and is not practical.

(Equation 2)

An object of the present invention is to provide a method of manufacturing a halftone phase shift mask capable of generating a light-shielding pattern of HTPSM in a practical processing time in view of the above-mentioned prior art.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art and achieve the above-mentioned object, a method of manufacturing a halftone phase shift mask according to the present invention comprises a plurality of rectangles arranged in a matrix. A halftone phase shift mask for manufacturing a halftone phase shift mask including a light shielding pattern having a transmitted light portion and a halftone transmitted light portion located therearound. Data and light-shielding pattern exclusion area data are extracted, and coordinates of the transmitted light portion determined in accordance with the light-shielding pattern area data are normalized and registered in the management unit. The light-shielding pattern area data and the light-shielding pattern exclusion area data are included in the layout data when the designer creates the layout data.

Next, based on the light-shielding pattern exclusion area data, a transmitted light portion in which the coordinates intersecting with the light-shielding pattern exclusion area are registered is searched with reference to the management means. Then, the coordinates of the newly generated rectangular transmitted light portion are registered in the management means so as to remove a portion of the searched transmitted light portion that intersects with the light-shielding pattern exclusion area. Next, after the process of removing the intersecting portion is completed for all the light-shielding pattern removal regions indicated by the light-shielding pattern exclusion region data, the light-shielding pattern of the light-shielding pattern is registered based on the coordinates of the transmitted light portion registered in the management unit. Generate drawing data.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a halftone phase shift mask according to an embodiment of the present invention will be described below. FIG. 1 is a flowchart of a method for manufacturing the halftone phase shift mask. Step S1: First, a designer operates the LSI design CAD apparatus to create layout data. At this time, the designer, if necessary, inserts light-shielding pattern area data indicating the light-shielding pattern 20 shown in FIG. 3 and light-shielding pattern exclusion area data indicating an area where the light-shielding pattern is excluded from the light-shielding pattern area in the layout data. Specify with. Here, the light-shielding pattern area data and the light-shielding pattern exclusion area data are described using coordinate values corresponding to those areas.

Step S2: The system searches the layout data, extracts light-shielding pattern area data and light-shielding pattern exclusion area data included in the layout data, and stores them in a memory (not shown).

Step S3: The system proceeds to step S2
Based on the light-shielding pattern area data and the light-shielding pattern exclusion area data extracted in, drawing data of the light-shielding pattern is generated. The processing in step S3 will be described later with reference to FIG.

Step S4: The system performs general graphic calculation processing, correction processing, and EB (Electro
n Beam) Performs conversion processing and drawing data generation processing to generate drawing data.

Step S5: The system generates drawing data corresponding to the superposition of the light-shielding pattern and the pattern other than the light-shielding pattern, based on the drawing data of the light-shielding pattern and the drawing data of the pattern other than the light-shielding pattern.

Step S6: The drawing data generated in step S5 is input to a drawing device, for example, EB drawing is performed, and a halftone phase shift mask is manufactured.

Hereinafter, the process of generating the drawing data of the light-shielding pattern shown in step S3 of FIG. 1 will be described. In this process, an array area table that manages rectangular areas forming a light-shielding pattern with rectangular coordinates (hereinafter also referred to as array area coordinates) is used. The array area coordinates are coordinate values of the lower left corner and the upper right corner of the rectangle indicating the light shielding pattern area, and are registered in the array area table after normalization according to the specification of the light shielding pattern to be generated. The array area table is managed so that by specifying a search rectangular area, the array area coordinates of the light-shielding pattern that intersects the search rectangular area can be extracted at high speed. In general, the intersection area search processing by area designation requires a large amount of computation,
Although it is difficult to perform high-speed processing by a computer, the number of array area coordinates handled by the array area table is as small as several hundreds at most, so that high-speed processing can be performed using a hash technique based on areas.

FIG. 2 is a flowchart of the process for generating the light-shielding pattern drawing data shown in step S3 of FIG. Step S11: The system resets (initializes) the array area table.

Step S12: The system normalizes the array area coordinate values corresponding to the light-shielding pattern area data extracted in step S2 shown in FIG. 1, and stores (registers) the normalized coordinate values in the array area table. An example of normalization when storing array area coordinates in the array area table will be described with reference to a light-shielding pattern 20 shown in FIG. For the sake of simplicity, it is assumed that the mask center is at coordinates (0, 0), and the array is offset so that one center of the transmitted light portion 21 of the light shielding pattern 20 is located at the coordinates (0, 0). . As shown in FIG. 3, the light-shielding pattern 20 has a square transmitted light portion 21 which is arranged in a matrix and has a side of 0.9 μm and a width of 0.1 mm.
And a 9 μm half transmitted light portion 22.

In this case, the X and Y coordinate values of the lower left corner and the upper right corner of all the transmitted light portions 21 of the light-shielding pattern to be created are represented by the following equation (3). That is, each array area coordinate is normalized so as to satisfy the following equation (3).

[0024]

(X, Y) = (1.8i−0.45, 1.8i−0.45) at the lower left corner of the transmitted light part 21 (X, Y) = (X, Y) at the upper right corner of the transmitted light part 21 (1.8i + 0.45, 1.8i + 0.45) (3) Here, i is an arbitrary integer and does not mean the same value.

In the present embodiment, since the light-shielding pattern area is cut by the light-shielding pattern exclusion area, array processing newly adds array area coordinates registered in the array area table. Therefore, the array area must not intersect the light-shielding pattern area due to the coordinate value change by normalization. Therefore,
In the process of normalizing the array area coordinate values, the coordinate values are:
The calculation shown in the following equation (4) is performed for normalization. By performing the normalization in this way, it is possible to prevent the array region from intersecting the light-shielding pattern region due to the normalization.

[0026]

(Equation 4)

When x1> x2 or y1> y2 as a result of the normalization processing based on the above equation (4), no graphic of the light-shielding pattern exists in the array area. Therefore, the array area is removed from the array area table.

Step S13: The system reads from the memory the light-shielding pattern exclusion area data X for which exclusion processing has not been performed yet.

Step S14: If the system determines that the exclusion processing has been completed for all the shading pattern exclusion areas indicated by the shading pattern exclusion area data, the system executes step S18; otherwise, the system proceeds to step S18.
15 is executed.

Step S15: The system searches the array area table for an array area A that intersects with the light shielding pattern exclusion area data X read in step S13. At this time, the system retrieves the array area A intersecting with the query area from the array area table as a query area without normalizing the area corresponding to the light-shielding pattern exclusion area data X read in step S13. . Here, the relationship between the extracted rectangular array area and the inquiry area is “A” to “N” in FIG.
Can be classified into 14 cases. Since the case of “O” does not intersect, it cannot be a search result. Further, when there is a circumscribed or inscribed relationship between the array area and the inquiry area, it can be considered that this is a special case of any of A to N. In FIG. 4, a solid line indicates a searched array area, and a dotted line indicates an inquiry area by a light-shielding pattern exclusion area.

Step S16: The system proceeds to step S16.
If the intersecting array area A is found in step 15, the process of step S17 is executed; otherwise, the process of step S13 is executed again.

Step S17: The system performs the following clip processing. In the clip processing, step S
The array area A acquired by the search processing of No. 15 is deleted from the array area table, and the area coordinates newly created according to the light-shielding pattern exclusion area are stored in the array area table as a new array area. This operation is performed very simply in each of the cases in FIG. For example, in the case of “J”, as shown in FIG.
Processing for calculating the coordinates of the two new areas 50, 51, 52 is performed. Here, the coordinates of the inquiry area 30 based on the light-shielding pattern exclusion area are ( _qx1 , _qy1 , _qx2 , _qy2 ). In the case of "J" in FIG.
The coordinates of the acquired array area 40 are (a _x1 , a _y1 , a _x2 ,
in the case of a _y2), the new area after the clip processing 51,5
The coordinates of 2, 53 are as follows.

The coordinates of the new area 50: (a _x1 , q _y1 , q _x1 , a _y2 ) The coordinates of the new area 51: (q _x2 , q _y1 , a _x2 , a _y2 ) The coordinates of the new area 52: (a _x1 , A _y1 , a _x2 , q _y1 )

When a new area is created, if the area is divided in such a direction that the aspect ratio becomes as small as possible, the final number of array areas can be reduced to some extent. However, the number of array regions to be handled is at most several hundreds and is not large, so that the effect of this is not so large. Similarly, “A” to “I” and “K” to
Even in the case of “N”, the new area coordinates after clipping are easily (ie, at high speed) calculated only by a combination of the coordinate values of the light-shielding pattern exclusion area and the coordinate values of the array area obtained from the array area table. it can. Here, the obtained coordinates of the new area are stored in the array area table after being normalized as array area coordinates.

Step S18: When the system completes the clip processing for all the light-shielding pattern exclusion areas,
Create and output drawing data. This processing is very simple, and all the array area coordinates stored in the array area table are normalized. Therefore, when drawing data is generated according to the specifications shown in FIG. Just do it. That is, if the coordinate values of the array area are (a _x1 , a _y1 , a
_x2 , _ay2 ), ( _ax1 , _ay1 , _ax1 + 0.
9, a _y1 +0.9) is created, and the number of pitches is equal to the number represented by the following equation (5) in the X-axis direction and the number represented by the following equation (6) in the Y-axis direction. Specify repeatedly at 8 μm.

[0036]

(Equation 5)

[0037]

(Equation 6)

Since the format of the actual drawing data is often divided into small areas, an array area is extracted from the table for each of the small areas, and processing is performed by processing clips in the small areas. it can. However, depending on the format, there is a case where it is necessary to cope with clip processing up to the rectangle of the light shielding pattern.

As described above, in the method of manufacturing a halftone phase shift mask according to the present embodiment, when a light-shielding pattern for HTPSM is created, data to be handled is consistently processed in the array area of the light-shielding pattern in the process. By using only the coordinates, the figure of the light shielding pattern is not directly handled, so that the amount of information to be handled can be extremely reduced. As a result, high-speed processing becomes possible. Further, when outputting the drawing data, the output is performed with the array area coordinates unchanged, so that the output size of the drawing data can be reduced (the compression ratio can be increased), and the time required for the output is at most several minutes of practical use. Order can be shortened.

[0040]

As described above, according to the method of manufacturing a halftone phase shift mask of the present invention, the amount of calculation for generating a light shielding pattern can be reduced, and the halftone phase shift mask can be processed in a practical processing time. A mask can be manufactured.

[Brief description of the drawings]

FIG. 1 is a flowchart of a method for manufacturing a halftone phase shift mask according to an embodiment of the present invention.

FIG. 2 is a flowchart of a process of generating drawing data of a light-shielding pattern shown in step S3 of FIG.

FIG. 3 is a diagram for explaining specifications of a light-shielding pattern;

FIG. 4 is a diagram for explaining a process in step S17 shown in FIG. 2;

FIG. 5 is a diagram for explaining clip processing in step S17 shown in FIG. 2;

FIG. 6 is a view for explaining a problem of a conventional method for manufacturing a halftone phase shift mask.

FIG. 7 is a diagram for explaining a light shielding pattern of a halftone phase shift mask.

FIG. 8 is a diagram for explaining a method of manufacturing a conventional halftone phase shift mask employing a repetitive drawing method.

FIG. 9 is a diagram for explaining a method of manufacturing a conventional halftone phase shift mask employing a graphic operation method.

[Explanation of symbols]

10, 13, 20: light-shielding pattern, 11, 21, half-tone transmitted light portion, 12, 22, ... transmitted light portion, 16: light-shielding pattern excluded region

Claims (6)

[Claims] 1. A halftone phase shift mask for producing a halftone phase shift mask including a light shielding pattern including a plurality of rectangular transmitted light portions arranged in a matrix and a halftone transmitted light portion located therearound. The light shielding pattern area data and the light shielding pattern exclusion area data are extracted from the layout data, and the coordinates of the transmitted light portion determined according to the light shielding pattern area data are normalized and registered in the management unit. Based on the light-shielding pattern exclusion area data, a search is made for a transmitted light portion in which the coordinates that intersect with the light-shielding pattern exclusion area are registered with reference to the management unit. The coordinates of the newly generated rectangular transmitted light portion are managed so as to remove the portion that intersects the light-shielding pattern exclusion region. After the processing of removing the intersecting portion is completed for all the light-shielding pattern exclusion areas indicated by the light-shielding pattern exclusion area data, light-shielding is performed based on the coordinates of the transmitted light part registered in the management means. A method for manufacturing a halftone phase shift mask for generating pattern drawing data. 2. The method of manufacturing a halftone phase shift mask according to claim 1, wherein the coordinates of the searched transmitted light portion are removed from the management means. 3. A method for manufacturing a light-shielding pattern, comprising:
From the coordinates of the transmitted light portion registered in the management means,
2. The method of manufacturing a halftone phase shift mask according to claim 1, wherein coordinates of a rectangular area are generated, and the drawing data is generated by performing repetitive processing using the coordinates of the rectangular area. 4. The method according to claim 1, wherein the normalization of the coordinates of the transmitted light portion is performed so as to reduce the area of the transmitted light portion. 5. The method according to claim 1, wherein said management means is table data which can be read and written mechanically by a computer. 6. A drawing data of a halftone phase shift mask based on drawing data generated based on data other than data for generating the light shielding pattern in the layout data and drawing data of the light shielding pattern. The method for manufacturing a halftone phase shift mask according to claim 1, wherein