JPH1152544A - Photomask and its production as well as baking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photomask which is free from peeling of a light shielding film while transporting and handling and a process for producing the same as well as a baking device for producing this photomask. SOLUTION: This process consists in forming a resist film 14 on a mask blank 16 formed with the light shielding film 12 on a substrate 10, selectively heating the prescribed regions exclusive of the peripheral edges of this mask blank and exposing the heated resist film with prescribed patterns. Further, the resist film at the peripheral edges is selectively dissolved and the exposed resist film is developed to the patterns. The light shielding film is etched with the patterned resist film as a mask to remove the light shielding film at the peripheral edges and the light shielding film is processed to the patterns.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask, a method of manufacturing the same, and a baking apparatus. More particularly, the present invention relates to a photomask in which a light-shielding film is not peeled during transportation and handling, a method of manufacturing the same, and a method of manufacturing the same To a baking device for performing

[0002]

2. Description of the Related Art A photomask used for photolithography includes a glass substrate and a light-shielding film formed on the glass substrate. Photomasks are broadly classified into master masks (actual size masks) and reticles (enlargement masks). The master mask may be formed by direct patterning using an electron beam lithography system, or may be formed by patterning via a reticle, which is an enlargement mask, and a photo repeater. In addition, the reticle is used not only as an enlarged mask for forming a master mask, but also in a microfabrication technique, may be used for patterning using a stepper without using a master mask.

[0005] Such a photomask is generally used in FIG.
As shown in (a), it is stored in the magazine 100. Upon receiving a predetermined command, the robot arm 102 unloads the predetermined photomask 124 from the magazine 100 and places it on a transport device (not shown) or the like. The photomask 124 placed on the transport device is transported to the exposure device and used for exposure.

However, as shown in the enlarged view of FIG. 6B, when the photomask 124 is carried out of the magazine 100 or carried into the magazine 100, the photomask 12
4 comes into contact with the magazine 100 and the photomask 1
The light-shielding film (not shown) formed on the peripheral portion of 24 may be peeled off. Similarly, when the photomask 124 is transported by using a transport device or the like, the peripheral portion of the photomask 124 may come into contact with the transport device or the like to peel off the light-shielding film. When the light-shielding film is peeled in this way, the peeled light-shielding film may become dust and adhere to the peripheral portion of the photomask 124 again.

Further, the photomask 124 to which the dust 106 adheres is washed by a quick dump rinse, which is a method of washing the water by alternately performing rapid drainage and supply of the washing liquid 108 to the washing tank 104 several times. Then, as shown in FIG. 7A, the dust 106 can be removed from the photomask 124.
May float on the surface of the cleaning liquid 108. Dust 10
If 6 floats on the surface of the cleaning liquid 108, the dust 106 may adhere to the photomask 124 in the process of draining the cleaning liquid 108 (see FIG. 7B).

[0006] When exposure is performed using the photomask 124 to which the dust 106 adheres, light is not applied to an area to be exposed, and a manufacturing defect may occur. In order to avoid such a problem, the magazine 1
00 and photomask 1 that may come into contact with the transport device
It is desirable not to form a light-shielding film on the peripheral portion of 24.

[0007]

However, the conventional photomask 124 does not form a light-shielding film on the periphery in consideration of prevention of dust generation. In addition, if an attempt is made to simultaneously remove the light-shielding film at the peripheral portion in the process of processing the light-shielding film into a predetermined pattern, the predetermined pattern must be exposed and the peripheral portion must be exposed in the exposure step. There is a problem that the time of the exposure process becomes very long in the exposure using the.

An object of the present invention is to provide a photomask in which a light-shielding film is not peeled off during transportation and handling, and a method for manufacturing the same. Another object of the present invention is to provide a baking apparatus for manufacturing the above photomask.

[0009]

The object of the present invention is to provide a resist film forming step of forming a resist film on a mask blank having a light-shielding film formed on a substrate, and selecting a predetermined region excluding a peripheral portion of the mask blank. A heating step of selectively heating, an exposure step of exposing a predetermined pattern to the heated resist film, and selectively dissolving the resist film in the peripheral portion, and developing the exposed resist film into the pattern. A developing step and an etching step of etching the light-shielding film using the patterned resist film as a mask, removing the light-shielding film at the peripheral portion, and processing the light-shielding film into the pattern. This is achieved by a method of manufacturing a photomask. Thus, the light-shielding film at the peripheral portion of the mask blank can be selectively etched, so that a photomask in which the light-shielding film does not peel off during transportation or handling can be provided.

In the above-described method for manufacturing a photomask, it is preferable that the resist film is formed of a positive resist whose dissolution rate is reduced by heating. Further, in the above-described method for manufacturing a photomask, it is preferable that the resist film is made of a positive resist whose cross-linking is caused by heating and the dissolution rate is reduced.

Further, the above object is achieved by a photomask manufactured by the above-described method for manufacturing a photomask. Accordingly, it is an object of the present invention to provide a photomask in which a light-shielding film does not peel off during transportation and handling. Further, the above object is a baking apparatus for heating a mask blank, comprising a heating means for heating a predetermined area excluding a peripheral part of the mask blank, and a cooling means for cooling the peripheral part of the mask blank. This is achieved by a baking apparatus characterized by the following. Thus, the resist film except for the peripheral portion of the mask blank can be selectively heated, so that a photomask in which the light-shielding film does not peel off during transportation or handling can be manufactured by the above manufacturing method.

Further, the above object is achieved by a baking apparatus for heating a mask blank, wherein the baking apparatus has heating means for heating only a predetermined area excluding a peripheral portion of the mask blank. Thus, the resist film except for the peripheral portion of the mask blank can be selectively heated, so that a photomask in which the light-shielding film does not peel off during transportation or handling can be manufactured by the above manufacturing method.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A photomask, a method of manufacturing the same, and a baking apparatus according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a characteristic diagram showing the dissolution rate of a positive resist. FIG. 2 is a process sectional view illustrating the method for manufacturing the photomask according to the present embodiment. FIG.
FIG. 2 is a sectional view showing the baking apparatus according to the present embodiment.

The photomask according to the present embodiment has been made in view of the above-described problems, and has no light-shielding film formed on the periphery of the photomask. Normal,
The peripheral portion of the photomask that may come into contact with the magazine or the transport device is 5 mm or less from the edge of the photomask.
The light-shielding film on the peripheral edge of is removed.

The photomask according to the present embodiment mainly uses the dissolution characteristics of the resist film to remove the light-shielding film at the peripheral portion in order to prevent the exposure time from being lengthened by exposing the peripheral portion. There are features. The method for manufacturing the photomask according to the present embodiment is made by paying attention to the fact that the dissolution rate of the unheated and unexposed positive resist, the dissolution rate of the exposed positive resist, and the dissolution rate of the heated positive resist are different from each other. Things.

The positive resist applied on the light-shielding film in this embodiment has a dissolution rate characteristic as shown in FIG.
As shown in FIG. 1, the dissolution rate of the positive resist after exposure is the fastest, and the dissolution rate of the positive resist after heating is the lowest. The dissolution rate of the unheated and unexposed positive resist is higher than the dissolution rate of the heated positive resist and lower than the dissolution rate of the exposed positive resist. The dissolution rate of the unheated and unexposed positive resist is higher than the dissolution rate of the positive resist after heating because the solvent in the positive resist is not easily evaporated because it is not heated, and the solvent weakens the molecular bonds of the positive resist. It is thought that it is. Many ordinary positive resists have such characteristics.

The method for fabricating the photomask according to the present embodiment will be explained with reference to FIG. First, a light shielding film 12 made of a chromium film having a thickness of about 90 to 110 nm is formed on a glass substrate 10.
The mask blank 16 on which the light shielding film 12 is formed is prepared.
A positive resist having a dissolution rate characteristic as shown in FIG. 1 is applied thereon to form a resist film 14 (FIG. 2A)
reference).

Next, as shown in FIG. 2B, the mask blank 16 on which the resist film 14 is formed is placed on a baking device 18 and soft bake is performed. As shown in FIG. 3, the baking device 18 according to the present embodiment includes a cooling plate around the baking plate 20 for heating an area excluding the peripheral portion of the mask blank 16 and a cooling plate for cooling the peripheral portion of the mask blank 16. 22 is provided. The shapes of the baking plate 20 and the cool plate 22 are formed so that the mask blank 16 can be placed thereon. Further, the dimensions of the baking plate 20 and the cool plate 22 are set such that when the mask blank 16 is placed, the peripheral portion 5 mm from the edge of the mask blank 16 is cooled by the cool plate 22. When soft baking is performed using such a baking device 18 as shown in FIG.
The resist film 14a excluding the peripheral portion of the mask blank 16 can be selectively heated without heating the resist film 14 at the peripheral portion of the mask blank 16. The cool plate is desirably forcibly cooled, but may be air-cooled by providing fins or the like.

In this embodiment, the dimensions of the baking plate 20 and the cool plate 22 are the same as those of the mask blank 1.
6 is set so as to cool the peripheral portion 5 mm from the edge, but is not limited to the peripheral portion 5 mm from the edge. If a slide mechanism or the like is provided, the region to be heated and the region to be cooled are optional. Can be set to The solvent of the resist film 14a heated by the baking plate 20 evaporates due to the heating and the adhesion to the glass substrate 10 is strengthened, so that the dissolution rate is reduced as shown in FIG. On the other hand, the resist film 1 on the periphery of the mask blank 16
Since No. 4 is not heated, the dissolution rate is higher than that of the resist film 14a after heating as shown in FIG.

Next, a predetermined pattern is exposed on the resist film 14a of the mask blank 16 using an electron beam drawing apparatus or the like. Thereafter, the mask blank 16 on which the resist film 14a has been exposed is developed. At this time, the developing solution is intensively supplied to the peripheral portion of the mask blank 16 by using a nozzle for flowing out the developing solution, and the dissolution of the resist film 14 at the peripheral portion of the mask blank 16 is promoted. Mask blank 16
The dissolution of the resist film 14 at the peripheral portion of FIG.
This is because the dissolution rate of the unheated and unexposed resist film 14 is slightly lower than the exposure rate of the exposed resist film 14a as shown in FIG. When the development is performed in this manner, the dissolution rate of the resist film 14 at the periphery of the mask blank 16 becomes substantially the same as the dissolution rate of the resist film 14a after exposure, and these dissolution rates are the same as those of the resist film 14a after heating. Therefore, the resist film 14 at the peripheral portion of the mask blank 16 is selectively dissolved, and the resist film 14a is processed into a predetermined pattern. Further, dust and the like generated in the manufacturing process up to now and adhering to the peripheral portion of the mask blank 16 are washed away by the developer (see FIG. 2C).

Thereafter, if the light-shielding film 12 is etched using the resist film 14a as a mask, the light-shielding film 12 on the periphery of the glass substrate 10 is etched and the light-shielding film 1 is etched.
2 are formed, and the photomask 24 according to the present embodiment can be manufactured. In this specification, a photomask is used as a concept including a master mask and a reticle.

As described above, according to the present embodiment, since the light-shielding film at the peripheral edge of the mask blank can be selectively etched, it is possible to provide a photomask in which the light-shielding film does not peel off during transportation or handling. Can be.
Further, according to the present embodiment, while selectively cooling the resist film on the peripheral portion of the mask blank and selectively heating the resist film excluding the peripheral portion of the mask blank, the resist of the mask blank is By selectively heating the film, a photomask in which the light-shielding film is not peeled off during transportation or handling can be manufactured.

[Second Embodiment] The method for fabricating a photomask according to a second embodiment of the present invention will be explained with reference to FIG.
FIG. 4 is a characteristic diagram showing the dissolution rate of a chemically amplified positive resist. The same components as those of the photomask, the method of manufacturing the same, and the baking apparatus according to the first embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

In the first embodiment, a nozzle is used to selectively dissolve the resist film 14 in a peripheral area 5 mm from the edge of the mask blank 16.
The developing solution is intensively supplied to the periphery of the mask blank 1
6, the dissolution of the resist film 14 at the peripheral portion of the mask blank 16 was promoted, but the dissolution of the resist film 14a after heating not only at the peripheral portion 5 mm from the edge of the mask blank 16 but also in the vicinity thereof was promoted. In some cases, a portion of the resist film 14a became thin. If the resist film 14a after heating becomes thin, the resist film 14a cannot resist etching when patterning the light-shielding film 12 using the resist film 14a as a mask, which may cause a manufacturing defect. The photomask manufacturing method according to the present embodiment uses the resist film 14 made of a chemically amplified positive resist in which cross-linking is caused by heating and the dissolution rate is reduced so that the above-described manufacturing defects do not occur. It has the main features.

The chemically amplified positive resist used in the present embodiment is characterized in that, when heated, cross-linking occurs to reduce the dissolution rate, and has a dissolution rate characteristic as shown in FIG. . As shown in FIG. 4, the dissolution rate of the positive resist after heating is lower than that of an unheated and unexposed positive resist due to the occurrence of a crosslinking reaction. In addition, the dissolution rate of the unheated and unexposed positive resist shows almost the same characteristics as the dissolution rate of the exposed positive resist. In addition, as a chemically amplified positive resist having such dissolution rate characteristics, a cross-linker (P-HSt / AA copolymer) using a copolymer of polyhydroxytylene and acrylic acid as a matrix polymer (Matrix Polymer) is used. As a cross-linker, naphthalene-ethyl vinyl ether (NP-EVE) and bisphenol-diethyl vinyl ether (BPA-DEVE) were used, and an acid generator (Pa
Anilinonaphthalene as ttern Acid Generation)
Diphenyliodonium salt (ANS-DPI) and dimethoxyanthracenesulfonic acid-diphenyliodonium salt (DIA
S) and a positive resist realized by using the above method can be applied.

Next, the method for fabricating the photomask according to the present embodiment will be explained. First, as in the first embodiment, a mask blank 16 having a light shielding film 12 formed on a glass substrate 10 is prepared, and a chemically amplified positive resist having characteristics as shown in FIG. Is applied to form a resist film 14. Next, the mask blank 16 is placed on a baking device 18 to perform soft baking. Thereby, the resist film 14a can be selectively heated without heating the resist film 14 at the peripheral portion of the mask blank 16.

In the resist film 14a heated by the baking plate, a cross-linking reaction occurs, and the dissolution rate is reduced as shown in FIG. On the other hand, since the resist film 14 at the peripheral portion 5 mm from the edge of the mask blank 16 is not heated, the dissolution rate is higher than the dissolution rate of the resist film 14a after heating. Therefore, in the development, the mask blank 16
The resist film 14 at the periphery of the resist film 14
It will dissolve at a rate almost equal to a.

Next, a predetermined pattern is exposed on the resist film 14a of the mask blank 16 using an electron beam drawing apparatus or the like. Thereafter, the mask blank 16 on which the resist film 14a has been exposed is developed. As shown in FIG. 4, the dissolution rate of the unheated and unexposed resist film 14 is substantially equal to the dissolution rate of the exposed resist film and faster than the dissolution rate of the heated resist film 14a. The unexposed resist film 14 and the exposed resist film dissolve quickly. Thereby, the resist film 14 at the peripheral portion of the mask blank is selectively dissolved, and the resist film 14a is processed into a predetermined pattern. At this time, dust and the like generated in the manufacturing process up to now and adhering to the peripheral portion of the mask blank 16 are also washed away by the developer.

Thereafter, if the light-shielding film 12 is etched using the resist film 14a as a mask, the light-shielding film 12 at the peripheral portion of the glass substrate 10 is etched, and the light-shielding film 12 is formed in a region other than the peripheral portion of the glass substrate 10. The photomask 2 according to the present embodiment is formed with a predetermined pattern
4 can be manufactured. As described above, according to the present embodiment, the dissolution rate of the unheated and unexposed resist film is substantially equal to the dissolution rate of the exposed resist film, and the chemical amplification type having a characteristic that the dissolution rate after heating is reduced. Since the positive resist is used, it is not necessary to intensively supply the developing solution to the peripheral portion of the mask blank by using a nozzle, which may cause a thinning of the resist film in a region near the peripheral portion of the mask blank. Therefore, it is possible to prevent defective manufacturing of the photomask.

[Third Embodiment] A baking apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG.
It is sectional drawing which shows the baking apparatus by this embodiment.
The same components as those of the photomask and the method of manufacturing the same according to the first and second embodiments shown in FIGS. 1 to 4 and the baking apparatus are denoted by the same reference numerals, and description thereof will be omitted or simplified.

The baking apparatus according to the present embodiment is shown in FIG.
As shown in (1), a cool unit 26 for cooling the mask blank 16 is provided on a baking plate 20 for heating the mask blank 16. Cool unit 26 is made of Teflon,
It is formed in a tubular shape so that water can flow inside.

The cool unit 26 is provided so as to be close to the periphery of the mask blank 16 when the mask blank 16 is placed on the baking plate 20. Since the cool unit 26 is close, the peripheral edge of the mask blank 16 is cooled. When soft baking is performed using such a baking device 18 while flowing water into the cool unit 26, the resist film 14 on the mask blank 16 excluding the peripheral edge is heated without heating the resist film 14 on the peripheral edge of the mask blank 16. The film 14a can be selectively heated.

[Modified Embodiment] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the first embodiment, a cooling plate may not be provided, and only a predetermined region excluding a peripheral portion of the mask blank may be heated by the baking plate. In the third embodiment,
The refrigerant flowing through the cool unit is not limited to water, but may be Freon or liquid nitrogen.

[0034]

As described above, according to the present invention, the light-shielding film at the peripheral portion of the mask blank can be selectively etched by utilizing the melting characteristics of the resist film. A photomask in which a film is not peeled can be provided.

Further, according to the present invention, it is possible to provide a baking apparatus for selectively heating a resist film excluding a peripheral portion of a mask blank. Thus, the resist film of the mask blank can be selectively heated, so that a photomask in which the light-shielding film does not peel off during transportation or handling can be manufactured by the above manufacturing method.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a dissolution rate of a positive resist.

FIG. 2 is a process sectional view illustrating the method for manufacturing a photomask according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing the baking apparatus according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a dissolution rate of a chemically amplified positive resist.

FIG. 5 is a sectional view illustrating a baking apparatus according to a second embodiment of the present invention.

FIG. 6 is a side view and an enlarged view showing unloading from the magazine.

FIG. 7 is a conceptual diagram showing re-adhesion of dust to a photomask.

DESCRIPTION OF SYMBOLS 10 ... Glass substrate 12 ... Light shielding film 14, 14a ... Resist film 16 ... Mask blank 18 ... Baking device 20 ... Baking plate 22 ... Cool plate 24 ... Photo mask 26 ... Cool unit 100 ... Magazine 102 ... Robot arm 104 ... Washing tank 106 ... Dust 108 ... Cleaning liquid 124 ... Photo mask

Claims (6)

[Claims] A resist film forming step of forming a resist film on a mask blank having a light-shielding film formed on a substrate; a heating step of selectively heating a predetermined region excluding a peripheral portion of the mask blank; An exposure step of exposing a predetermined pattern to the heated resist film; a developing step of selectively dissolving the resist film at the peripheral portion and developing the exposed resist film into the pattern; Etching the light-shielding film using a resist film as a mask, removing the light-shielding film at the peripheral portion, and processing the light-shielding film into the pattern. 2. The method of manufacturing a photomask according to claim 1, wherein the resist film is made of a positive resist whose dissolution rate is reduced by heating. 3. The method of manufacturing a photomask according to claim 1, wherein the resist film is formed of a positive resist whose heating causes cross-linking to reduce the dissolution rate. . 4. A photomask manufactured by the method for manufacturing a photomask according to claim 1. Description: 5. A baking apparatus for heating a mask blank, comprising: a heating unit for heating a predetermined region excluding a peripheral portion of the mask blank; and a cooling unit for cooling the peripheral portion of the mask blank. Baking equipment characterized. 6. A baking apparatus for heating a mask blank, comprising a heating means for heating only a predetermined area excluding a peripheral portion of the mask blank.