JPH11133585A - Mask for exposure and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the formation highly accurate and fine resist patterns by regularly forming the desired patterns of a mask for forming the fine patterns and the dummy patterns. SOLUTION: A photoresist is subjected to the first exposure by using a first photomask 11 and this photoresist is subjected to the second exposure by using a second photomask 12. The required resist patterns are formed on the photoresist by the first exposure and the second exposure. In such a case, the first photomask 11 is formed with the desired patterns 101 and the dummy patterns 102 at respective regularly arranged plural grid points. The second photomask 12 is formed with the dummy patterns 102 of the size larger than the size of the first patterns at the selected grid points among the plural grid points described above. Even if the patterns are formed finer, the regular arrangement of the desired patterns and the dummy patterns is possible. The repeating characteristic of the patterns is assured by the exposure using the first photomask 11, by which DOF is improved and the exposure of the highly accurate and fine patterns and the formation of the resist patterns are made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure mask such as a photomask and a photo reticle used for manufacturing a semiconductor device, and more particularly, to an exposure mask for performing pattern formation on a semiconductor device with high accuracy and its exposure. It relates to a manufacturing method.

[0002]

2. Description of the Related Art At present, an optical lithography technique using a photomask and a reduction projection exposure apparatus is used as a technique for forming a resist pattern formed on a semiconductor device. Due to the fine dimensions of the pattern formed on the semiconductor device accompanying this, the above-mentioned optical lithography technology has a
pth Of Focus (hereinafter, referred to as DOF)) is important. It is known that in order to secure the DOF, it is effective to improve the repeatability of a pattern formed on a semiconductor device. However, an isolated line pattern cannot satisfy the repeatability.
It is difficult to secure the above-mentioned DOF. For this reason,
For such an isolated line pattern, a technique has been proposed in which a dummy pattern is arranged in the vicinity of the isolated line pattern and repeatability is ensured by the dummy pattern. For example, an example disclosed in Japanese Unexamined Patent Publication No. 8-45810 will be described.

In the technique described in this publication, FIG.
As shown in FIG. 12B, a first pattern in which a plurality of dummy patterns 102 (here, two dummy patterns 102 each) are formed on both sides of the desired pattern 101 as shown in FIG. A photomask 11A is formed. Then, by performing pattern exposure on the semiconductor substrate using the first photomask 11A, desired patterns and dummy patterns are formed as shown in FIG. 13A. Then, as shown in FIG. 13B, a second photomask 12A of a pattern exposing only the dummy pattern without exposing the desired pattern is formed, and the dummy pattern 102 is formed by using the second photomask 12A. As a result, a state occurs in which only the desired pattern is not exposed on the semiconductor substrate, and the exposure of the desired pattern is realized.

FIG. 14 is a diagram showing this state.
As shown in FIG. 19A, a positive photoresist 2 is applied on a semiconductor substrate 1, and in a first exposure step, the photoresist 2 shown in FIG.
By performing reduced projection exposure on the photoresist 2 using the first photomask 11A shown in (1), a region other than the desired pattern 101 and the dummy pattern 102 of the photoresist is exposed to form the first exposed portion 21. Is done. Next, as shown in FIG. 14B, the second
By performing reduced projection exposure on the photoresist 2 using a photomask 12A, the dummy pattern 1 is exposed.
The second area 22 is formed by exposing the area 02. Therefore, only the desired pattern 101 is not exposed, and by developing this photoresist 2, the exposed portion of the body-shaped photoresist is dissolved by the developing process, and the exposed portion is not dissolved, and
As shown in FIG. 14C, only the desired pattern is left as a photoresist pattern. Thereafter, the desired pattern can be formed on the semiconductor substrate by etching the surface of the semiconductor substrate 1 using the desired pattern.

[0005]

As described above, by performing exposure using the photomask 11A in which the dummy pattern 102 is disposed in the vicinity of the desired pattern 101, the repeatability of the pattern is improved, thereby improving the DOF. Although it is effective to perform the above, when a plurality of desired patterns are present, if dummy patterns are provided for each of the desired patterns, the dummy patterns interfere with each other, or may interfere with other desired patterns. In some cases, there is a problem that the effect of improving the DOF is reduced. For example, as shown in FIG. 15A, when two desired patterns 101 are present at a required interval, and dummy patterns 102 are arranged in a grid pattern with a pitch dimension Px for each desired pattern 101. If the space between the desired patterns 101 is small,
Since the dummy pattern 102 arranged between the two desired patterns interferes with another desired pattern or the dummy pattern, the dummy pattern cannot be arranged between the desired patterns 101, and the repeatability for improving the DOF is reduced. It cannot be secured. Also, as shown in FIG.
Even when a space for arranging the dummy patterns 102 is secured between the desired patterns 101, the respective dummy patterns 102 overlap with each other, and similarly, a problem arises in that the repeatability of the patterns cannot be secured.

An object of the present invention is to provide an exposure mask and a method for manufacturing the same, which ensure the repeatability of such a dummy pattern and enable a pattern to be formed on a semiconductor device using a photomask with high accuracy. Is to provide.

[0007]

According to the present invention, a first exposure is performed on a photoresist using a first photomask, and a second exposure is performed on the photoresist using a second photomask. In an exposure mask for performing exposure and forming a required resist pattern on the photoresist by the first exposure and the second exposure, the first photomask has a plurality of regularly arranged lattice points. A first pattern is formed on each of the plurality of grid points, and the second photomask has a second pattern having a size equal to or greater than the one pattern formed at a grid point selected from the plurality of grid points. It is characterized by. The first pattern includes a required pattern for pattern formation and a dummy pattern, and the second pattern is formed in a region including the dummy pattern. The second pattern is the same pattern as the dummy pattern, or is formed in a region including the dummy pattern and a region between the dummy patterns.

Further, in the manufacturing method of the present invention, a first exposure is performed on a photoresist using a first photomask, and a second exposure is performed on the photoresist using a second photomask. When manufacturing an exposure mask for forming a required resist pattern on the photoresist by the first exposure and the second exposure, a required pattern is formed in the creation of the first photomask. A step of setting a plurality of grid points having regularity in an area, and a step of arranging a first pattern including a desired pattern and a dummy pattern at each of the set grid points; Is characterized by comprising a step of arranging a second pattern having a size equal to or larger than the dummy pattern at a grid point where the dummy pattern is arranged. In this case, when arranging the second pattern, the second pattern may be arranged in a region including both the dummy pattern and a region between the dummy patterns.

More specifically, the method of manufacturing an exposure mask according to the present invention will be described with reference to the flowchart of FIG. 1. The method includes a lattice point setting step S1, a desired pattern designing step S2, and a dummy pattern designing step S3. I have. In the grid point setting step S1, a grid point area and a grid point interval are set.
In the desired pattern design step S2, pattern data of a desired pattern is created and arranged on grid points in the grid point area. Further, in the dummy pattern design step S3,
Dummy pattern data is created, and the dummy pattern is positioned so as to fill a lattice point where a desired pattern is not arranged.
Then, a first photomask and a second photomask are manufactured in a mask manufacturing step S4 based on the pattern data obtained from the lattice point setting step, the desired pattern designing step, and the dummy pattern designing step.

In the first photomask, the desired pattern and the dummy pattern are arranged so as to fill all the lattice points in the lattice point area, so that repeatability is ensured over all the patterns of the first photomask. DOF in an exposure step using the first photomask is improved. Also,
Since the second photomask is configured as a photomask for erasing the dummy pattern, an arbitrary desired pattern shape can be easily obtained by the pattern of the second photomask.

[0011]

Next, a first embodiment of the present invention will be described with reference to the drawings. First, FIG. 2A is a diagram for explaining a grid point setting step, and shows a grid point area 31.
Are set as an area 32 where the desired pattern 101 is arranged and an area 33 where the dummy pattern 102 in the outer peripheral area of this area can be arranged. In this grid point number determination process,
The position coordinates of the grid point area 31 are output. here,
The coordinates (x1, yl) of the lower right point and the upper left point of the area, (x
2, y2)) and the grid point interval (Px, Py) are output. The output format is the number of grid points in the x and y directions (i,
The format using j) may be used.

Next, FIG. 2B is a diagram for explaining a desired pattern design step. Pattern data of a desired pattern 101 to be arranged in the desired pattern arrangement area 32 is created, and the created pattern data is stored in the grid point area 31. Place on grid points. Then, the pattern data of the desired pattern 101 and the position where the pattern data is arranged are output. Here, (i, j) =
(3,6) (6,3) (8,5) (8,6) (9,4)
(9,5) (9,6) is output. )

Next, FIG. 2C is a diagram for explaining a dummy pattern designing process. A dummy pattern data is created, and the dummy pattern 102 is arranged on a lattice point in the lattice point area 31. At this time, it goes without saying that the dummy pattern 102 is arranged so as to fill the lattice points in the lattice point area 31 where the desired pattern 101 is not arranged. Further, in the dummy pattern designing step, the dummy pattern data and the position where the dummy pattern data is arranged are output.

Then, a first photomask 11 and a second photomask 12 are formed based on the pattern shown in FIG. First photomask 11 shown in FIG.
Is created using the position coordinates of the grid point area 31 in FIG. 2A, the grid point interval, the desired pattern data and the dummy pattern data in FIGS. 2B and 2C. At this time,
In the first photomask 11, the desired pattern 101 and the dummy pattern 102 are formed as dark portions, that is, the first pattern in which exposure light is shielded. Further, the second photomask 12 shown in FIG.
It is created using the position coordinates of the grid point area 31 in FIG. 2A, the grid point interval, and the dummy pattern data in FIG. At this time, the brightness of the second photomask 12 is created such that the dummy pattern 102 is a bright portion, that is, a second pattern through which exposure light is transmitted.

A method for forming a photoresist pattern using the first and second photomasks formed as described above will be described. First, as shown in FIG. 4A, a negative resist is applied on the semiconductor substrate 1 to form a resist film 2.
Next, a reduced projection exposure using the first photomask 11 is performed to form a first exposed portion 21 having the first pattern on the resist film 2 on the semiconductor substrate 1.
The first exposure portion 21 is formed in a region where the desired pattern and the dummy pattern of the first photomask do not exist. Next, as shown in FIG. 4B, reduction projection exposure using a second photomask 12 is performed, and a second exposure comprising the second pattern is performed on the resist film 2 on the semi-exclusive substrate 1. The part 22 is formed. The second exposure section 22 is an area where the dummy pattern exists. As a result, the entire region excluding the desired pattern 101 is irradiated with the exposure light. Therefore, by performing development processing on this resist, a resist pattern in which the resist is removed only in the desired pattern region is obtained as shown in FIG. By etching the semiconductor substrate 1 using this resist pattern, only the region of the desired pattern is etched, and the desired pattern is formed.

As can be seen from this embodiment, in the present invention, all desired patterns 101
Since the dummy pattern 102 and the dummy pattern 102 are arranged on the uniquely set lattice points, the desired pattern 101 and the dummy pattern 102 or the dummy pattern 102 and the dummy pattern 102 can be transposed without overlapping. Further, since the dummy pattern 102 is arranged so as to fill the lattice points where the desired pattern 101 is not arranged, when the arrangement position of the desired pattern 101 is determined, the dummy pattern 102 is determined.
Is also uniquely determined. Therefore, in the first photomask 11 created based on the desired pattern and the dummy pattern, the pattern is arranged in the entire lattice point region 31 with the desired pattern and the dummy pattern. The pattern 101 ensures repeatability. Accordingly, in the first exposure step of performing the reduced projection exposure using the first photomask 11, repetition is ensured and DOF is improved.

The effect of improving the DOF in the exposure step using the first photomask 11 is shown by a light intensity simulation. Here, as an example of the case where the positive resist is used and the repeatability is not perfect, an example of the present invention using the negative resist and the first photomask 11 using the arrangement of the hole patterns shown in FIG. 5B, the arrangement of the hole patterns filling all the lattice points shown in FIG. 5B was used. Further, the conditions of the light intensity simulation are as follows:
8nm, lens numerical aperture (NA) in reduced projection exposure
Was set to 0.55 and the condition for using the annular illumination method was used. The lattice point interval was 0.4 μm, and the hole pattern size was 0.2 × 0.2 μm. FIG. 6 shows a depth of focus curve obtained from the light intensity simulation. From this figure, the DOF was defined as the focal range where the change in the dimension value from the design dimension value (0.2 μm) was within 10%, and this was calculated. This result indicates that the pattern arrangement shown in FIG.
F is about 0.7 μm, and FIG.
In this pattern arrangement, it was about 1.2 μm, from which it was confirmed that the present invention was effective in improving DOF.

In the present invention, the size H2 of the pattern data of the dummy pattern 102 as shown in FIG.
Can be designed to have a dimension value different from the pattern dimension Hl of the desired pattern 101 shown in FIG. 7A, but in this case, the pattern data of the dummy pattern 102 is set to 1 in the dummy pattern designing step. By creating the individual pieces, it is possible to change the pattern data dimensions of all the dummy patterns 102 on which the pieces are arranged.

In the first embodiment, the pattern of the second photomask is formed so as to expose only the dummy pattern. However, since it is sufficient to expose a region other than the desired pattern, the second photomask is exposed. Also, the pattern of the mask can be formed more easily. For example, the desired pattern 101 and the dummy pattern 102 having the arrangement shown in FIG.
On the other hand, as shown in FIG.
A dummy pattern may be designed as a pattern obtained by adding an additional pattern 104 indicated by oblique lines between 02. In this manner, the second photomask can be formed in a pattern in which a continuous region of the dummy pattern and the additional pattern is a light-transmitting region, thereby facilitating the manufacture of the second photomask 12 and In the second exposure process using this, particularly, the alignment of the mask becomes easy.

Here, as shown in FIG. 9, the pattern data of the additional pattern 104 is designed such that the arrangement position (i + 1, j) (i) is adjacent to the arrangement position (i, j) of the dummy pattern 102. , J + 1) (i + 1, j + 1) to determine whether there is a dummy pattern 102, and generate additional pattern data accordingly. That is, when there is a dummy pattern 102 at the adjacent arrangement position (i + 1, j), the pattern shown in FIG. 9A is added, and the dummy pattern 102 is added at the arrangement position (i, j + 1).
If there is, add the pattern shown in FIG.
If there is a dummy pattern 102 at the arrangement position (i + 1, j + 1), an additional pattern 104 shown in FIG. 9C may be added.

Further, according to the present invention, on the first photomask 11, the area other than the lattice point area 31 is set as a dark part and the lattice point area 3
By forming the peripheral pattern 103 other than 1 on the second photomask 12, it is possible to obtain a resist pattern of a different peripheral pattern 103 using the same first photomask 11. For example, FIG.
As shown in FIG. 0 (a), a lattice point region 31 is formed on the first photomask 11, and the other portions are dark portions.
Here, by setting a portion other than the lattice point region 31 on the first photomask 11 as a dark portion, the resist film 2 other than the lattice point region 31 becomes an unexposed portion in the first exposure.
A portion other than the lattice point region 31 can be patterned on the second photomask 12. That is, FIG.
By forming the peripheral pattern 103 shown in (b) on the second photomask 12, a resist pattern of the peripheral pattern 103 can be obtained. FIG. 10 (c)
The second photomask 12 which is a bright portion other than the lattice point region 31 shown in FIG. 3 is formed, and the resist film 2 can be left without forming a pattern.

In the present invention, the first photomask 1
In No. 1, since the desired pattern 101 is arranged so as to fill all the grid points on the grid point area 31, the desired pattern having a different layout is changed by changing the layout of the dummy pattern 102 created on the second photomask 102. 101
Is obtained. Therefore, the same first photomask 1
1 can be used to obtain a resist pattern in which the arrangement of the desired pattern 101 is different. For example, in the example of FIG. 11, the first pattern in which a pattern is formed
As shown in FIGS. 11A to 11D, the dummy pattern 1
By forming four types of second photomasks 12 having different arrangements of the second photomask 02 and performing second exposure using the second photomasks, it is possible to obtain a resist pattern in which the desired pattern 101 has a different arrangement. Can be.

In each of the above embodiments, the pattern data for forming the first photomask 11 and the second photomask 12 is shown in a preferred example with a small number of pattern data. The present invention is not limited to the above embodiments, and it is also possible to output pattern data in another more general format.

[0024]

As described above, according to the present invention, the first pattern is arranged on each of the regular lattice points on the first photomask. The pattern and the dummy pattern can be arranged regularly, so that the pattern repeatability can be ensured in the exposure using the first photomask.
It is possible to improve OF and realize exposure of a highly accurate and fine pattern and formation of a resist pattern. The second pattern formed on the second photomask is
The second pattern may be formed in the dummy pattern of the first photomask or in a region between the dummy patterns including the dummy pattern. Therefore, the manufacturing accuracy of the second pattern can be reduced, and the manufacturing becomes easy. Furthermore, even if the same first photomask is used, an arbitrary resist pattern can be formed only by changing the second pattern of the second photomask.
It is possible to increase the use value of the mask.

[Brief description of the drawings]

FIG. 1 is a manufacturing method (design step) of an exposure mask of the present invention.
5 is a flowchart for explaining FIG.

FIG. 2 is a mask pattern diagram for explaining a mask manufacturing process according to the first embodiment of the present invention.

FIG. 3 is a pattern diagram of first and second masks according to the present invention.

FIG. 4 is a view for explaining an exposure step using a mask of the present invention.

FIG. 5 is a pattern diagram of a mask for confirming a DOF effect.

FIG. 6 is a diagram showing a DOF effect.

FIG. 7 is a diagram for explaining a modified example of a dummy pattern.

FIG. 8 is a pattern diagram of first and second masks having different dummy patterns.

FIG. 9 is a diagram for explaining a method of designing a dummy pattern.

FIG. 10 is a pattern diagram of first and second masks according to another embodiment of the present invention.

FIG. 11 is a pattern diagram of a second mask according to still another embodiment of the present invention.

FIG. 12 is a diagram showing a conventional desired pattern and a mask pattern.

FIG. 13 is a diagram showing first and second mask patterns in the related art.

FIG. 14 is a view for explaining a conventional mask exposure step.

FIG. 15 is a pattern diagram for explaining a conventional problem.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor substrate 2 negative photoresist 11 first photomask 12 second photomask 21 first exposure unit 22 second exposure unit 101 desired pattern 102 dummy pattern 103 peripheral pattern 104 additional pattern

Claims (7)

[Claims] 1. A first exposure is performed on a photoresist using a first photomask, and a second exposure is performed on the photoresist using a second photomask.
In an exposure mask for forming a required resist pattern on the photoresist by the first exposure and the second exposure, the first photomask has a plurality of regularly arranged lattice points. One pattern is formed, and the second photomask has a second pattern having a size equal to or larger than the first pattern formed at a grid point selected from the plurality of grid points. Exposure mask. 2. The exposure method according to claim 1, wherein the first pattern includes a required pattern for forming a pattern and a dummy pattern, and the second pattern is formed in a region including the dummy pattern. For mask. 3. The exposure mask according to claim 2, wherein the second pattern is the same pattern as the dummy pattern. 4. The exposure mask according to claim 2, wherein the second pattern is formed in a region including the dummy pattern and a region between the dummy patterns. 5. The exposure mask according to claim 1, wherein the photoresist is a negative resist, the first pattern is a pattern that blocks light, and the second pattern is a pattern that transmits light. 6. A first exposure is performed on the photoresist using a first photomask, and a second exposure is performed on the photoresist using a second photomask.
When manufacturing an exposure mask for forming a required resist pattern on the photoresist by the first exposure and the second exposure, in the production of the first photomask, a region where a required pattern is to be formed is regularly formed. Setting a plurality of grid points having different properties, and arranging a first pattern including a desired pattern and a dummy pattern at each of the set grid points. Arranging a second pattern having a size equal to or larger than the dummy pattern at a grid point where the dummy pattern is arranged. 7. The method of manufacturing an exposure mask according to claim 6, wherein when arranging the second pattern, the second pattern is arranged in a region including both the dummy pattern and a region between the dummy patterns.