JPH01112243A - Production of photomask - Google Patents

Abstract

PURPOSE:To prevent the occurrence of electrostatic destruction in the main pattern of a mask part by limiting the exposure area of step exposure to the range of a metallic film and continuously leaving the metallic film throughout around a mask part forming area. CONSTITUTION:An exposure area 50 of step exposure is limited to the range of a metallic film 22, and metallic films 22 and 63 are so constituted that they are continuously left throughout around a mask part forming area 61. That is, the metallic film left throughout around the mask forming area charges most of static electricity during the production process to relatively suppresses charging of static electricity to each mask part. Thus, the conventional production process is followed as it is to produce a photomask without causing electrostatic destruction of the main pattern.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a photomask, the purpose of this method is to prevent electrostatic damage from occurring in the main pattern of the mask portion during the manufacturing process. In a method for manufacturing a photomask including a step exposure process in which step exposure is performed by repeatedly exposing each chip, the exposure area by the step exposure is limited to within the range of the metal film, and the metal film covers the entire circumference of the mask forming area. It is configured so that it is left continuously over the entire period.

[Industrial application field]

The present invention relates to a method for manufacturing a photomask.

In general, a photomask is manufactured by using process steps 1 to 12 shown in FIG. In the figure, 1 is a step of forming a chromium film on the glass base, 2 is a step of forming a resist film on the chrome ridge, 3 is a step exposure step in which the resist film is repeatedly exposed chip by chip, and 4 is a step exposure step of repeatedly exposing the resist film on a chip-by-chip basis. Step 5 is a water washing step to remove the developing solution; 6 is an etching step for the chromium film; 7 is a water washing step to remove the etching solution; 8 is a stripping step to remove the resist film; 9 is water washing. Step 10 is an acid treatment step using sulfuric acid to decompose and remove organic matter on the surface, step 11 is a water washing step to remove sulfuric acid, and step 12 is a drying step.

FIG. 4 shows one mask section 15 among the many mask sections constituting the photomask manufactured by the above process. 16, 17 and 18, 19 are islands, respectively, forming the main pattern.

Each water washing process 5, 7, 9, and 11 is performed by spraying pure water onto the surface of the object. Pure water has a high specific resistance. In particular, in the washing steps 9 and 11, the photomask pattern is rubbed with pure water, and static electricity tends to accumulate in each of the islands 16 to 19. If this static electricity escapes with discharge, a portion of the island will be chipped and the main pattern 14 will be damaged by static electricity, resulting in a defective photomask.

Therefore, in the photomask manufacturing method, it is necessary to make the main pattern less susceptible to electrostatic damage.

[Conventional technology]

FIG. 5 is a diagram illustrating a step exposure process of a conventional photomask manufacturing method.

Reference numeral 20 denotes an object to be exposed, and as shown in FIG. 6, a chromium film 22 which is a metal film is formed on a circular glass plate 21 which is a transparent substrate, and resists 1 to 22 are further formed on the surface of this chromium film 22. This is a configuration in which a film 23 is formed.

Step exposure is performed by a step exposure device based on a program stored in a computer, and the area surrounded by a solid line in FIG. 5 is set as exposure 1 rear 25. Exposure is repeatedly performed within this exposure area 25. The portions surrounded by two-dot chain lines are step exposure sections 26, respectively.

Now, when looking at each corner portion of the exposure area 25 and the step exposure portions 26 to 26-16 in the vicinity thereof, a portion thereof protrudes outside the chromium film 22.

Therefore, the photomask 30 manufactured through the step exposure described above becomes as shown in FIG.

The upper surface of this photomask 30 has a mask part forming area 31 in which the mask parts 15 are arranged in rows and columns, a lattice-like scribe line 45, and a residual chromium film left around this mask part forming area 31. 32 and more.

The remaining chromium film 32 does not exist continuously over the entire circumference of the photomask 30 in the circumferential direction, but is cut into pieces along the way. 33 to 44 are portions where the remaining chromium film 32 is not present. In particular, the remaining chromium film 32 is missing over a relatively wide width at the portion indicated by 33°44.

Furthermore, the area S1 of the remaining chromium film 32 is also reduced.

[Problem that the invention seeks to solve]

In the photomask 30 manufactured by the above manufacturing method,
For example, as shown in FIG. 8, electrostatic damage often occurred in which a portion of the island 19 was chipped. If electrostatic damage occurs in the mask portion 15 of -, the photomask becomes a defective product, and the conventional manufacturing method has a problem in that the yield is low.

Further, the present inventor investigated the parts of the mask section 15 where electrostatic discharge damage occurred, and found that it was particularly common near the part where the residual chromium film was missing, which is indicated by the code 33.4=1.

Based on the above inspection results, it is an object of the present invention to provide a photomask manufacturing method that prevents electrostatic damage from occurring in the main pattern of the mask portion during the manufacturing process.

[Means for solving problems]

The present invention provides a photomask manufacturing method including a step exposure process in which a resist film on the surface of a metal film on a transparent substrate is repeatedly exposed chip by chip. The metal film is configured to remain continuously over the entire circumference of the mask portion forming region.

[Effect]

The metal film left over the entire circumference of the mask forming region charges most of the static electricity during the manufacturing process, and relatively suppresses static electricity charging to each mask portion.

(Example) Fig. 1 is a diagram showing a step exposure process of an embodiment of the Illll method for a photomask of the present invention.In the figure, the same reference numerals are given to the parts that are substantially the same as those shown in Fig. 5. attach

Reference numeral 50 denotes an exposure area, and the exposure area 50 is a portion surrounded by a solid line that extends from the exposure area 25 to the step exposure section 26 . ．． This is the part excluding numbers 1 to 26-16.

As a result, the surrounding step exposure sections 26-2Q to 26-
37 also does not protrude outside the chromium film 22, and the step exposure portion 26 is entirely on the chromium film 22.

In this way, the exposure area 50 can be easily made narrower than before by partially changing the computer program.

The photomask 60 manufactured through the step exposure described above becomes as shown in FIG.

The upper surface of this photomask 60 has a mask part forming area 61 in which the mask parts 15 are arranged in rows and columns, a lattice-like scribe line 62, and a residual chromium film left around this mask part forming area 61. 63 and more.

Here, the mask portion forming region 61 does not protrude outward from the chromium film 22 and is limited to a region inside the outer periphery of the chromium film 22.

As a result, the remaining chromium film 62 is removed from the mask portion forming region 61.
It exists continuously, unbroken, all around its circumference.

Further, the area S2 of the remaining chromium film 62 is larger than the area S1.

When each mask portion 15 of this photomask 30 was inspected, no electrostatic damage was found.

Therefore, according to the manufacturing method of this embodiment, the photomask 60 can be manufactured with high yield.

The reason why electrostatic damage does not occur is that, firstly, the residual chromium film 63 exists continuously over the entire circumference, so that most of the static electricity generated in the washing steps 9 and 11 is caused by the residual chromium film 63. The amount of static electricity charged on the film 63 and the main pattern is relatively small. Secondly, since both ends of all scribe lines 62 are connected to the remaining chromium film 63, the static electricity charged on the main pattern is reduced. The surrounding residual chromium film 6 is immediately removed through the scribe line 62.
It is thought that this is because they are let go by 3.

Further, in FIG. 2, 70 indicates the outer shape of the wafer.

Even if the exposure area is narrowed, the mask forming area 61 is wider than the wafer and covers the entire wafer, so there is no problem in patterning the upper surface of the wafer.

In addition, in order to prevent the electrostatic damage mentioned above, a method is adopted in which a transparent conductive film is formed on a glass plate, and a chromium film is formed on this, and the static electricity charged in the main pattern is released to the ground through the transparent conductive film. It is also possible, but this method requires an additional step to form a transparent conductive film.
It is unfavorable in terms of manufacturing cost and other Q- points.

〔Effect of the invention〕

As explained above, according to the present invention, a photomask can be manufactured without adding a new process, by following the conventional manufacturing process as it is, and without causing electrostatic damage to the main pattern. . However, the photomask,
It can be manufactured with good yield without increasing manufacturing cost.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a step exposure process in an embodiment of the photomask manufacturing method of the present invention, FIG. 2 is a plan view of a photomask manufactured by the manufacturing method of the present invention, and FIG. 3 is a general view of a photomask. Figure 4 is an enlarged view of the - mask part of the photomask; Figure 5 is a diagram explaining the step exposure process in the conventional photomask manufacturing method; Figure 6 is the exposure target. FIG. 7 is a plan view of a photomask manufactured by a conventional manufacturing method, and FIG. 8 is an enlarged view showing an example of electrostatic damage in a mask portion. In the figure, 3 is a step exposure process, 15 is a mask part, 20 is an exposure target, 21 is a glass plate, 22 is a chrome film, 23 is a resist film, 26 is a step exposure part, 50 is an exposure area, 60 is a photomask, Reference numeral 61 indicates a mask forming region, 62 indicates a scribe line, and 63 indicates a remaining chromium film. ■Figure 6 (λo and Toma λ2 Figure 2 Figure 5 Figure 6 Figure 7 @ Figure 8

Claims (1)

[Claims] A photomask manufacturing method including a step exposure step (3) in which a resist film (23) on the upper surface of a metal film (22) on a transparent substrate (21) is repeatedly exposed chip by chip. , the exposure area (50) by the step exposure is limited to within the range of the metal film (22), and the metal film (22, 63) forms a mask portion forming area (61).
A method for manufacturing a photomask, which is configured to remain continuously over the entire circumference of the photomask.