JPH1184627A - Manufacture of photomask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a desired photosensitive resin pattern on a semiconductor substrate by manufacturing a photomask having an OPC (light proximity effect correction) pattern corresponding to design and to prevent a pseudo defect from being detected when the mask is inspected by improving the roundness of the OPC pattern. SOLUTION: The mask substrate obtained by successively forming a first light shielding film 2a and a second light shielding film 2b on a transparent substrate 1 is used. Then, the main pattern is formed on the film 2b by first plotting. Continuously, second plotting is executed and the OPC pattern is formed on the film 2a. By forming the main pattern and the OPC pattern by executing the different plotting in such a way, the accuracy of the OPC pattern is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photomask for a projection exposure apparatus, and more particularly to a photomask used for forming a fine pattern in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art At present, in a manufacturing process of a semiconductor device, an optical lithography technique is mainly used to form a pattern on a semiconductor substrate. In optical lithography,
A photomask (an exposure original plate on which a pattern consisting of a transparent area and a light-shielding area is formed by a reduction projection exposure apparatus,
When the reduction ratio is not 1: 1, it is particularly called a reticle, but here, each is called a photomask. The pattern of (2) is transferred onto a semiconductor substrate coated with a photosensitive resin, and a predetermined pattern of the photosensitive resin can be obtained by development. Conventional optical lithography techniques have responded mainly to development of exposure apparatuses, particularly to miniaturization of semiconductor element patterns by increasing the NA of the projection lens system. Where N
A (numerical aperture) corresponds to how much light the lens can collect, and the larger the value, the more light that can be collected, and the better the lens performance. Further, as is generally well known as the Rayleigh equation, the critical resolution R (the size of the critical fine pattern that can be resolved) and NA are R = K1 × λ / NA (where K1 is There is a relationship depending on a process such as the performance of the photosensitive resin, and λ is the wavelength of light. The larger the NA, the finer the limit resolution becomes.

Recently, various super-resolution techniques have been studied, and the limit of optical lithography has been improved to below the exposure wavelength. Generally, the super-resolution technique is a technique for improving the light intensity distribution on the image plane by controlling the transmittance and the phase on the pupil plane of the illumination optical system, the photomask, and the projection lens system.

Here, a halftone type phase shift mask will be briefly described. The phase shift mask causes a phase difference of 180 degrees between transmitted lights in adjacent transmission areas on the mask, and forms a steep image on an imaging plane (semiconductor substrate) due to interference between lights having phases different by 180 degrees. It is a method of forming. In the halftone method, a semi-transparent film is used instead of a light-shielding film of a normal mask, and a setting is made so that a phase difference of 180 degrees occurs between light transmitted through the translucent film and light transmitted through a transparent region around the translucent film. FIG. Hereinafter, the film that is translucent and generates a phase difference of 180 degrees is referred to as a halftone film. As a material for the halftone film,
Chromium oxynitride, molybdenum oxynitride silicide, chromium fluoride, or the like is used, and its transmittance is 4% to 20%.
Range is common. However, when light leaks over the entire surface of the mask, there is a problem in that the leaked light causes film loss (decrease in resist film thickness) in the photosensitive resin at the boundary between adjacent exposure regions. Therefore, a light-shielding film is formed on the translucent film so that light does not leak to unnecessary portions. In the manufacture of a mask, a halftone film and a light shielding film were sequentially formed.
A layered mask substrate is used. Then, the light-shielding film and the halftone film are processed in the first drawing, and then the predetermined portion of the light-shielding film is removed in the second drawing to expose the halftone film.

Although the limit of optical lithography has been extended by such a super-resolution technique, the deformation of the pattern shape due to the optical proximity effect has become remarkable near the resolution limit. The optical proximity effect refers to a phenomenon in which the size and shape of a certain photosensitive resin pattern change due to the influence of a peripheral pattern. For example, problems such as 1) a dimensional difference between a line-and-space pattern and an isolated pattern, 2) shrinking of a line tip, and 3) rounding of a corner portion occur.

[0006] Therefore, optical proximity correction (hereinafter referred to as OPC. This is called Optical Proximity Correction, Optical Proximity Corre).
This is an abbreviation for ction. ) Has been actively studied. This is a method of obtaining a desired photosensitive resin pattern by deforming the mask pattern in advance, contrary to the deformation of the photosensitive resin pattern. FIG. 23 shows an example of an OPC mask for preventing rounding and shrinking of a line tip. FIG. 23A shows a normal pattern 3 without correction.
It is one. FIG. 23B shows a correction pattern 32 called a hat which locally thickens the corner tip, and FIG. 23C shows a correction pattern 33 called a serif provided with fine projections. is there. They may also be used for different purposes,
There is also a method called an auxiliary pattern 34 shown in FIG. The auxiliary pattern 34 is used for controlling the size and also for increasing the depth of focus of the isolated pattern. Lines,
By arranging a fine pattern that does not resolve itself, such as a hat and an auxiliary pattern, at the pattern corner, the shape of the obtained photosensitive resin pattern can be improved.

Also, a program for automatically designing such an OPC mask is commercially available, and has been gradually used for manufacturing semiconductor devices. On the other hand, technology development for drawing such a fine pattern is also being performed in a mask manufacturing method.

A drawing apparatus used for manufacturing a mask is an electron beam drawing apparatus or a laser direct drawing apparatus. It is known that the linearity (the relationship between the design dimensions and the obtained mask dimensions) of these mask drawing apparatuses is reduced below 1 μm on the mask. Electron beam lithography systems are also used in the manufacture of semiconductor devices. In semiconductor device lithography, high linearity up to a fine pattern of about 0.2 μm is obtained using a high acceleration of 50 keV or more. However, since the mask substrate is made of synthetic quartz (SiO ₂ ), charge-up is severe, and drawing at high acceleration such as drawing of a semiconductor element cannot be applied. At present, the linearity at 1 μm or less on the mask is extremely reduced, and dimensional control becomes difficult when patterns of different shapes and dimensions are mixed. Therefore,
When a fine pattern such as serif is used as the OPC method,
When the exposure amount is adjusted to the main pattern size, the size of the serif pattern becomes extremely small, and the effect of improving the pattern shape cannot be obtained.

Therefore, a mask manufacturing method for producing an OPC mask as designed has been developed. For example,
There is a method of changing the exposure amount for each pattern. That is, a thin portion of the pattern is made thicker by lowering the exposure amount. By changing the exposure amount for each pattern in this manner, the linearity can be improved. In addition, a method of etching the light-shielding film was studied. Usually, wet etching is used for processing the light shielding film (chromium). Since side etching occurs in wet etching, the corners are rounded and a fine pattern such as serifs cannot be formed. Therefore, the processing of the light-shielding film is changed to dry etching, and the side etching is suppressed to reduce the OP.
The processing accuracy of the C mask is improved.

[0010]

As described above,
In a conventional method of manufacturing an OPC mask, a semiconductor element pattern (hereinafter, referred to as a main pattern) and an additional pattern (hereinafter, referred to as an OPC pattern) such as serifs are formed at the same time. It was difficult to process. That is, since the OPC pattern such as serif is in contact with the main pattern, if the size of the OPC pattern is adjusted by the exposure amount,
The dimensions of the main pattern have also changed. Changes in the dimensions of the main pattern affect the characteristics of the semiconductor element. Therefore, there has been a need for a mask manufacturing method that makes the size and shape of the OPC pattern such as serifs close to the design without changing the size of the main pattern.

Further, the change from wet etching to dry etching has improved the processing accuracy of the OPC pattern, but this alone has not been sufficient. That is, by changing to dry etching and preventing side etching of the light-shielding film, the light-shielding film can be processed according to the photosensitive resin pattern serving as an etching mask. However, since the photosensitive resin pattern is deformed due to the optical proximity effect in electron beam exposure during mask drawing and the effect during development of the photosensitive resin,
It was not possible to form an OPC pattern as designed just by using dry etching.

If the OPC mask pattern is deformed (dimensions or rounds), not only sufficient effects cannot be obtained, but also problems occur in the inspection process. That is, the roundness of the OPC pattern is all detected as a pseudo defect in the mask inspection apparatus. For this reason, in practice, the detection sensitivity of the inspection device must be lowered to perform inspection without detecting the deformation of the OPC pattern.
The reliability of the mask has been extremely reduced.

It is an object of the present invention to obtain a desired photosensitive resin pattern on a semiconductor substrate by manufacturing a photomask having an OPC pattern of a design. Another object of the present invention is to prevent detection of a pseudo defect in mask inspection by improving roundness of an OPC pattern.

[0014]

The present invention employs the following means to solve the above-mentioned problems.

(1) In a method of manufacturing a photomask having a main pattern to be transferred onto an image forming surface and an OPC pattern for improving the shape of the main pattern, the main pattern and the OPC pattern are formed in separate drawing steps. A method for manufacturing a photomask to be formed.

(2) Using a mask substrate on which a first light-shielding film and a second light-shielding film are sequentially formed on a transparent substrate, applying a photosensitive resin on the mask substrate, and writing a main pattern. Performing, a step of etching the second light-shielding film using the photosensitive resin pattern as a mask after development, a step of once removing and applying the photosensitive resin again, a step of drawing an OPC pattern, and a step of drawing the photosensitive resin after development. The method for manufacturing a photomask according to (1), further comprising a step of etching the first light-shielding film using the pattern and the second light-shielding film as a mask.

(3) Using a mask substrate in which a first light-shielding film and a second light-shielding film are sequentially formed on a transparent substrate, applying a photosensitive resin on the mask substrate, and writing an OPC pattern. Performing, a step of etching the second light-shielding film using the photosensitive resin pattern as a mask after the development, a step of once removing and applying the photosensitive resin again, a step of drawing a main pattern, and a step of drawing the photosensitive resin after the development. The method for manufacturing a photomask according to (1), further comprising a step of etching the first light-shielding film using the pattern and the second light-shielding film as a mask.

(4) Using a mask substrate in which a light-shielding film and an etching mask layer for the light-shielding film are sequentially formed on a transparent substrate,
A step of applying a photosensitive resin on the mask substrate, a step of drawing a main pattern, a step of etching the etching mask layer using the photosensitive resin pattern after development as a mask, and once removing and applying the photosensitive resin again The photomask manufacturing method according to (1), further comprising the steps of: performing a step of forming an OPC pattern; and a step of etching the light shielding film using the photosensitive resin pattern after development and the etching mask layer as a mask.

(5) Using a mask substrate in which a light-shielding film and an etching mask layer of the light-shielding film are sequentially formed on a transparent substrate,
Applying a photosensitive resin on the mask substrate; OP
A step of drawing a C pattern, a step of etching the etching mask layer using the photosensitive resin pattern as a mask after development, a step of once peeling and coating the photosensitive resin again, a step of drawing a main pattern, and a step of drawing a main pattern. The method for producing a photomask according to (1), further comprising a step of etching the light-shielding film using the photosensitive resin pattern and the etching mask layer as a mask.

(6) The method for manufacturing a photomask according to (1), wherein a main pattern and an OPC pattern are separately formed on each of the mask substrates using two mask substrates.

(7) a step of applying a photosensitive resin to a mask substrate on which a halftone phase shift film and a light shielding film are sequentially formed on a transparent substrate; a step of drawing a main pattern on the mask substrate; A step of etching the light-shielding film using the photosensitive resin pattern as a mask, a step of once removing and applying the photosensitive resin again to draw an OPC pattern, and a step of halftone using the photosensitive resin pattern and the light-shielding film as a mask after development; The method for manufacturing a photomask according to the above (1), comprising a step of etching the phase shift mask.

(8) A step of applying a photosensitive resin to a mask substrate on which a halftone phase shift film and a light shielding film are sequentially formed on a transparent substrate; a step of drawing an OPC pattern on the mask substrate; A step of etching the light-shielding film using a photosensitive resin pattern as a mask; a step of once peeling and applying the photosensitive resin again to draw a main pattern; and a halftone process using the photosensitive resin pattern and the light-shielding film as a mask after development. The method for manufacturing a photomask according to the above (1), comprising a step of etching the phase shift mask.

[0023]

According to the present invention, since the main pattern and the OPC pattern are processed in separate steps, they can be processed under optimum conditions, and the shape of the OPC pattern can be improved. In particular, for this purpose, the present invention uses a mask substrate in which two layers of light-shielding films are formed using different materials that can be selectively etched. Since the main pattern and the OPC pattern are formed in different layers, the roundness of the corner of the connection portion between the main pattern and the OPC pattern can be eliminated, and the defect inspection can be facilitated.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Four embodiments of a method for manufacturing a photomask according to the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. 1 to 6 show a photomask in a main manufacturing process. FIG.
(B) is a sectional view.

First, as shown in FIG. 1, a first light shielding film 2a and a second light shielding film 2 are formed on a transparent substrate 1 made of synthetic quartz.
A mask substrate on which b is sequentially formed is manufactured. Here, the first
The light-shielding film 2a and the second light-shielding film 2b need to be selectively etchable. Here, the first light shielding film 2a
Is made of ordinary tungsten silicide (WSi: 1).
00 nm). A chromium-based material (Cr / CrxOy: 100 nm) is used as the material of the second light-shielding film 2b.
Is used.

Then, as shown in FIG. 2, a photosensitive resin 21 is applied to the two-layer mask substrate, and electron beam drawing of the main pattern 11 is performed.

Next, a developing process is performed as shown in FIG.
After forming the pattern of the photosensitive resin 21, the second light-shielding film 2b is etched. Here, the second light shielding film 2b
Since a chromium-based material is used, dry etching using a gas containing chlorine as a main component is performed for the etching.

Next, as shown in FIG. 4, the photosensitive resin 21 is once peeled off, the photosensitive resin 21 is applied again, and then a serif pattern (OPC pattern) 12 is drawn. Here, the serif patterns 12a to 12d correspond to the main pattern 11
Are located at the four corners.

Then, as shown in FIG. 5, after forming a pattern of the photosensitive resin 21 by development, the first light shielding film 2 is formed.
a is etched. Here, since the refractory metal silicide is used as the material of the first light shielding film 2a, the etching is performed by dry etching using a gas containing fluorine as a main component. At this time, since the second light-shielding film 2b is made of chromium, it is not etched by this dry etching.

Then, as shown in FIG.
1 is peeled off to manufacture a photomask having an OPC pattern.

FIG. 7B shows the shape of the serif portion when the photomask is manufactured by the method for manufacturing a photomask of the present invention. In the present invention, since the main pattern and the serif pattern are processed by different drawing, the corner of the connection portion can be formed completely at a right angle. In the conventional technique shown in FIG. 7A, the concave corner 41 becomes extremely rounder than the convex corner 42 due to the optical proximity effect at the time of electron beam drawing. The method of the present invention has an advantage that the concave corner can be formed with high precision. Also, as described above, since the main pattern and the serif pattern are formed by separate drawing, drawing can be performed under optimal conditions for each, and the dimensional accuracy of the serif pattern can be improved. .

If side etching does not occur in the etching of the first light shielding film 2a, the second light shielding film 2
Since b does not affect the exposure characteristics of the mask, the second light-shielding film may be finally peeled off, leaving only the first light-shielding film 2a. Here, only the second light shielding film 2b can be easily removed by wet etching using ceric ammonium nitrate.

There are other combinations of materials for the first and second light-shielding films than those described above. For example, the combination of the first light-shielding film and the second light-shielding film is made of silicon and chromium or chromium and ruthenium. Combinations may be used.

The drawing order of the main pattern and the OPC pattern can be reversed from that of the above embodiment.

A second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. These figures show a photomask in a main manufacturing process, and each figure shows (a)
Is a plan view, and (b) is a sectional view.

First, as shown in FIG. 8, on a transparent substrate 1 made of synthetic quartz, a mask substrate in which a light-shielding film 2 and an etching mask layer 3 of the light-shielding film 2 are sequentially formed is manufactured. Here, the etching mask layer 3 needs to be a material that can withstand the etching of the light shielding film 2. Here, a normal chromium-based material is used for the first light shielding film 2 (chrome 70).
A multilayer film having a thickness of 30 nm and a chromium oxide of 30 nm as an antireflection film). Then, a second light shielding film (etching mask layer 3)
Is made of ruthenium oxide (20 nm).
In the photomask of the present invention, it is not necessary for the second light-shielding film to shield the exposure light. However, if the second light-shielding film is too thin, defects such as pinholes will occur.

Then, as shown in FIG. 9, a photosensitive resin 21 is applied to the two-layer mask substrate to form an OPC pattern 12a.
To d are drawn. Here, these OPC patterns are arranged at four corners of the main pattern.

Next, as shown in FIG. 10, a developing process is performed to form a pattern of the photosensitive resin 21, and then the etching mask layer 3 is etched. Here, since ruthenium oxide is used for the etching mask layer 3, dry etching using a gas containing oxygen as a main component is performed for the etching.

Next, as shown in FIG. 11, the photosensitive resin 21 is once peeled off, the photosensitive resin 21 is applied again, and then the main pattern 11 is drawn.

Then, as shown in FIG. 12, after the pattern of the photosensitive resin 21 is formed by development, the light shielding film 2 is etched. Here, since a chromium-based material is used as the material of the light-shielding film 2, a dry etching using a gas containing chlorine as a main component is performed for the etching. At this time, since the etching mask layer 3 uses ruthenium oxide, it is not etched by this dry etching.

Then, as shown in FIG. 13, the photosensitive resin 21 is peeled off, and then the etching mask layer 3 is removed to manufacture a photomask having an OPC pattern. Here, the etching mask layer 3 can be easily removed by peeling the oxygen plasma.

The etching mask layer need not be removed as long as it does not affect the exposure characteristics of the mask. For example, this ruthenium oxide has low surface reflectivity,
In particular, there is no problem even if the etching mask layer is not removed. However, when a material having a high reflectivity such as silicon is used, unless the etching mask layer is removed, a problem occurs that the exposure light reflected on the semiconductor substrate is reflected on the photomask and returns to the semiconductor substrate again. Need to be removed.

There are other combinations of materials for the light-shielding film and its etching mask layer than those described above. For example, molybdenum silicide and chromium, or chromium and silicon nitride may be used.

The drawing order of the main pattern and the OPC pattern can be reversed from that of the above embodiment.

Next, a third embodiment of the present invention will be described with reference to FIGS. These figures show a photomask in a main manufacturing process, in which (a) is a plan view and (b) is a cross-sectional view.

First, in this mask manufacturing method, FIG.
As shown in (1), a substrate in which a halftone phase shift film 4 and a light shielding film 2 are formed on a transparent substrate 1 is used. This uses a mask substrate of a conventional halftone type phase shift mask. The halftone phase shift film 4 is made of molybdenum oxynitride silicide, has a transmittance of 6% for KrF excimer laser light at a thickness of 120 nm, and has a phase difference of 180 degrees. The light-shielding film 2 is made of a normal chrome film (chrome 70 nm and antireflection chrome oxide 30 n).
m). Next, as shown in FIG. 15, a photosensitive resin 21 is applied on this mask substrate, and a main pattern 1 is formed.
1 is drawn. Then, as shown in FIG. 16, after the pattern of the photosensitive resin 21 is formed by a development process, the light shielding film 2 is processed by dry etching using a chlorine-based gas. Next, as shown in FIG.
, The photosensitive resin 21 is applied again, and this time, O
The PC patterns 12a to 12d and the light-shielding pattern 13 are drawn. Here, the light-shielding pattern is for preventing unnecessary leakage of light which has been conventionally used, and although not shown, a frame of a light-shielding region having a width of about 500 μm is also formed around the exposure region. Then, as shown in FIG. 18, after forming a pattern of the photosensitive resin 21 by a developing process,
Fluorine-based gas (for example, CHF ₃ , CF ₄ ,
The halftone phase shift film 4 is processed by dry etching using SHF ₆ ). Then, the photosensitive resin 21 is peeled off as shown in FIG.

In the halftone type phase mask,
Conventionally, a mask substrate having a two-layer structure of a halftone phase shift film and a light shielding film has been used.
The drawing was performed multiple times. In the present invention, the drawing accuracy of the OPC pattern is improved by dividing the main pattern and the OPC pattern into the first drawing and the second drawing.

In the present mask manufacturing method, OP
It is also possible to remove the light shielding film 2 on the C pattern. However, the effect of the OPC pattern differs between when the light-shielding film on the OPC pattern is not removed and when it is removed.
If the light-shielding film on the OPC pattern is removed to form a halftone region, the light intensity in the OPC pattern portion is further reduced, and the same effect as that obtained when the OPC pattern is enlarged is obtained.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 20, in this embodiment, two mask substrates each having a light-shielding film formed on a transparent substrate 1 are used, and a main pattern 11 and an OPC pattern 12 (serif pattern) are separated from each other. It is formed on a substrate. By dividing into two pieces in this way, the main pattern 11
And OPC patterns 12a to 12d can be mask-drawn under optimum conditions. Therefore, the dimensional accuracy of the OPC pattern can be improved.

The photomask manufactured by this manufacturing method is
As shown in FIG. 21, the same effect as that of a normal OPC mask can be obtained by overlapping use during exposure. Further, as shown in FIG.
The image of the C pattern 12 is transferred onto the mask on which the main pattern 11 is formed, and the overlapped image is transferred to the projection lens system 10.
Even if an image is formed on the semiconductor substrate 103 by the method 2, the same effect as that of the original one OPC mask can be obtained.

[0053]

As described above, according to the photomask manufacturing method of the present invention, since the main pattern and the OPC pattern are formed by separate drawing, the OPC is performed without affecting the size and shape of the main pattern. The pattern can be formed accurately. Therefore, the performance of the semiconductor element is stabilized, and the yield is improved.

Further, since the method of manufacturing a photomask of the present invention improves the roundness of the OPC pattern, it is possible to prevent the detection of a pseudo defect in the mask inspection.

[Brief description of the drawings]

FIGS. 1A and 1B show a first step of a photomask according to a first embodiment of the present invention, wherein FIG. 1A is a plan view and FIG.

FIGS. 2A and 2B show a second step of the photomask according to the first embodiment of the present invention, wherein FIG. 2A is a plan view and FIG.

FIGS. 3A and 3B show a third step of the photomask according to the first embodiment of the present invention, wherein FIG. 3A is a plan view and FIG.

FIGS. 4A and 4B show a fourth step of the photomask according to the first embodiment of the present invention, wherein FIG. 4A is a plan view and FIG.

FIGS. 5A and 5B show a fifth step of the photomask according to the first embodiment of the present invention, wherein FIG. 5A is a plan view and FIG.

6A and 6B show a photomask manufactured according to the first embodiment of the present invention, wherein FIG. 6A is a plan view and FIG. 6B is a cross-sectional view.

FIGS. 7A and 7B show the shape of a serif pattern (OPC pattern), wherein FIG. 7A shows a shape obtained by a conventional photomask manufacturing method, and FIG. 7B shows a shape obtained by a photomask manufacturing method of the present invention.

8A and 8B show a first step of a photomask according to a second embodiment of the present invention, wherein FIG. 8A is a plan view and FIG. 8B is a cross-sectional view.

9A and 9B show a second step of the photomask according to the second embodiment of the present invention, wherein FIG. 9A is a plan view and FIG. 9B is a cross-sectional view.

10A and 10B show a third step of the photomask according to the second embodiment of the present invention, wherein FIG. 10A is a plan view and FIG. 10B is a cross-sectional view.

FIGS. 11A and 11B show a fourth step of the photomask according to the second embodiment of the present invention, wherein FIG. 11A is a plan view and FIG.

12A and 12B show a fifth step of the photomask according to the second embodiment of the present invention, wherein FIG. 12A is a plan view and FIG. 12B is a cross-sectional view.

13A and 13B show a photomask manufactured according to the second embodiment of the present invention, wherein FIG. 13A is a plan view and FIG. 13B is a cross-sectional view.

14A and 14B show a first step of a photomask according to a third embodiment of the present invention, wherein FIG. 14A is a plan view and FIG. 14B is a cross-sectional view.

15A and 15B show a second step of the photomask according to the third embodiment of the present invention, wherein FIG. 15A is a plan view and FIG. 15B is a cross-sectional view.

FIGS. 16A and 16B show a third step of the photomask according to the third embodiment of the present invention, wherein FIG. 16A is a plan view and FIG.

FIGS. 17A and 17B show a fourth step of the photomask according to the third embodiment of the present invention, wherein FIG. 17A is a plan view and FIG.

FIGS. 18A and 18B show a fifth step of the photomask according to the third embodiment of the present invention, wherein FIG. 18A is a plan view and FIG.

19A and 19B show a photomask manufactured according to the third embodiment of the present invention, wherein FIG. 19A is a plan view and FIG. 19B is a cross-sectional view.

FIGS. 20A and 20B are plan views showing steps of a photomask according to a fourth embodiment of the present invention, wherein FIG. 20A is a mask substrate on which a main pattern is formed, and FIG. 20B is a mask substrate on which an OPC pattern is formed; Are respectively shown.

FIG. 21 is a cross-sectional view illustrating a state in which photomasks manufactured according to a fourth embodiment of the present invention are used in an overlapping manner during exposure.

FIG. 22 is a cross-sectional view showing a state in which a photomask manufactured according to a fourth embodiment of the present invention is projected onto a semiconductor substrate using a lens system during exposure.

FIG. 23 shows a pattern of a conventional OPC mask;
(A) shows a normal pattern without correction, (b) shows a correction pattern called a hat, (c) shows a correction pattern called a serif, and (d) shows an auxiliary pattern.

[Explanation of symbols]

Reference Signs List 1 transparent substrate 2 light shielding film 2a first light shielding film 2b second light shielding film 3 etching mask layer 4 halftone phase shift film 11 main pattern 12, 12a, 12b, 12c, 12d OPC pattern 13 light shielding pattern 21 photosensitive resin 101 Lens system 102 Projection lens system 103 Semiconductor substrate

Claims (8)

[Claims] In a method of manufacturing a photomask having a main pattern to be transferred onto an image forming surface and an OPC pattern for improving the shape of the main pattern, the main pattern and the OPC pattern are formed in separate drawing steps. A method of manufacturing a photomask. 2. A step of applying a photosensitive resin on the mask substrate using a mask substrate in which a first light-shielding film and a second light-shielding film are sequentially formed on a transparent substrate, and drawing a main pattern. A step of etching the second light-shielding film using the photosensitive resin pattern as a mask after development, a step of once peeling and applying the photosensitive resin again, a step of drawing an OPC pattern, and a step of drawing the photosensitive resin pattern after development. 2. The method according to claim 1, further comprising the step of etching the first light-shielding film using the second light-shielding film as a mask. 3. A step of applying a photosensitive resin on the mask substrate using a mask substrate in which a first light-shielding film and a second light-shielding film are sequentially formed on a transparent substrate, and drawing an OPC pattern. A step of etching the second light-shielding film using the photosensitive resin pattern as a mask after development, a step of once peeling and applying the photosensitive resin again, a step of drawing a main pattern, and a step of drawing the photosensitive resin pattern after development. 2. The method according to claim 1, further comprising the step of etching the first light-shielding film using the second light-shielding film as a mask. 4. A step of applying a photosensitive resin on the mask substrate using a mask substrate on which a light-shielding film and an etching mask layer for the light-shielding film are sequentially formed on a transparent substrate, and a step of drawing a main pattern. A step of etching the etching mask layer using the photosensitive resin pattern as a mask after the development, a step of once peeling the photosensitive resin and applying it again,
2. The method for manufacturing a photomask according to claim 1, further comprising: a step of drawing a PC pattern; and a step of etching the light-shielding film using the photosensitive resin pattern after development and the etching mask layer as a mask. 5. A step of applying a photosensitive resin on the mask substrate using a mask substrate in which a light-shielding film and an etching mask layer for the light-shielding film are sequentially formed on a transparent substrate, and a step of drawing an OPC pattern. A step of etching the etching mask layer using the photosensitive resin pattern after development as a mask, a step of once removing and applying the photosensitive resin again, a step of drawing a main pattern, and a step of drawing the photosensitive resin pattern after development and the etching. The method according to claim 1, further comprising a step of etching the light-shielding film using a mask layer as a mask. 6. The method for manufacturing a photomask according to claim 1, wherein two mask substrates are used, and a main pattern and an OPC pattern are separately formed on each of the mask substrates. 7. A step of applying a photosensitive resin to a mask substrate on which a halftone phase shift film and a light shielding film are sequentially formed on a transparent substrate; a step of drawing a main pattern on the mask substrate; Etching the light-shielding film using the photosensitive resin pattern as a mask, once removing the photosensitive resin and applying it again to draw an OPC pattern, and after development, using the photosensitive resin pattern and the light-shielding film as a mask, to obtain a halftone phase. 2. The method according to claim 1, further comprising a step of etching the shift mask. 8. A step of applying a photosensitive resin to a mask substrate on which a halftone phase shift film and a light shielding film are sequentially formed on a transparent substrate; a step of drawing an OPC pattern on the mask substrate; Etching the light-shielding film using the photosensitive resin pattern as a mask, once peeling and applying the photosensitive resin again to draw a main pattern, and after development, using the photosensitive resin pattern and the light-shielding film as a mask, to obtain a halftone phase. 2. The method according to claim 1, further comprising a step of etching the shift mask.