JP2008197234A - Photomask for proximity exposure, exposure method and exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photomask for proximity exposure capable of suppressing the sticking of sublimated material originated from a resist. <P>SOLUTION: The photomask for proximity exposure has a pattern made of light shielding material formed on a light-transmissive substrate, wherein a coated film made of a photocatalyst which exhibits photocatalyst action by the exposure light or a coated film including the photocatalyst is formed on the surface on which the pattern is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a proximity exposure photomask (hereinafter also simply referred to as “photomask”), an exposure method, and an exposure apparatus.

  A flat panel display such as a liquid crystal display or a plasma display used for a thin television or the like is manufactured by transferring a photomask pattern onto a substrate by proximity exposure transfer using a divided sequential exposure method. As a conventional sequential sequential exposure apparatus of this type, for example, a photomask having a smaller area than that of the substrate is used on a large area substrate, and the photomask is held on a mask stage and a substrate coated with resist is used on a work stage. Hold the two close to each other, and in this state, move the work stage stepwise relative to the photomask, and irradiate the substrate with UV light for pattern exposure from the photomask side at each step. This pattern is exposed and transferred onto a substrate (for example, see Patent Document 1).

  In the exposure described above, the photomask and the resist applied to the substrate tend to be closer to each other, and the gap may approach 30 to 50 μm. However, the resist contains dyes, pigments, organic solvents, and the like, and these are sublimated by ultraviolet irradiation and adhere to the pattern forming surface of the photomask. If a sublimate adheres to the light-transmitting region of the photomask, the amount of transmitted UV light will be reduced, or unnecessary patterns will be transferred to the resist and accurate patterning will not be possible. At the same time, the photomask with the sublimate attached is washed and reused.

  For this reason, the exposure apparatus and its peripheral devices, apparatuses, and lines must be temporarily stopped in order to replace the mask, which is a great obstacle to increasing production efficiency.

  In order to increase production efficiency, it is considered to shorten the exposure time. However, since it is necessary to increase the irradiation intensity of ultraviolet rays, the amount of sublimation generated increases, and exposure until mask replacement is achieved. Less often.

JP 2006-350315 A

  The present invention has been made in view of such a situation, and an object thereof is to provide a photomask for proximity exposure in which adhesion of resist-derived sublimates is suppressed.

In order to achieve the above object, the present invention provides the following.
(1) A proximity exposure photomask in which a pattern made of a light-shielding material is formed on a light-transmitting substrate, and a film made of a photocatalyst that exhibits a photocatalytic action by exposure light on the surface on which the pattern is formed, or A photomask for proximity exposure, wherein a film containing a photocatalyst is formed.
(2) An exposure method comprising performing proximity exposure using the photomask for proximity exposure described in (1) above.
(3) An exposure apparatus, wherein the exposure is performed with the proximity exposure photomask described in (1) above.

  In the photomask for proximity exposure according to the present invention, since a film made of a photocatalyst or a film containing a photocatalyst is formed on the surface on which a pattern is formed, even if a resist-derived sublimate is attached, It is decomposed by photocatalytic action at the degree of exposure, and a clean state can be maintained for a longer time than before. As a result, the number of exposures until the mask replacement is increased and the productivity is greatly improved.

  Moreover, since the photocatalytic action increases as the irradiation intensity of ultraviolet rays increases, the exposure time can be shortened, and the productivity can be further improved.

  Hereinafter, the present invention will be described in detail.

  As schematically shown in FIG. 1, the photomask for proximity exposure according to the present invention is a film comprising a photocatalyst that exhibits a photocatalytic action by exposure light on the surface of the translucent substrate 1 on which the pattern 2 is formed, or the photocatalyst. (Hereinafter referred to as “photocatalyst film 3”).

  The translucent substrate 1 is generally a synthetic quartz glass plate subjected to high-definition polishing. The pattern 2 is made of a light shielding material such as chromium, and a thin film made of the light shielding material is formed on one surface of the translucent substrate 1, and is drawn in a predetermined pattern by a photo-resist process.

  The photocatalyst is not particularly limited as long as it is a material that exhibits photocatalytic action by exposure light. For example, ultraviolet rays are frequently used as exposure light today, and photocatalysts that exhibit photocatalytic action by ultraviolet rays are exemplified below.

  Anatase-type titanium dioxide is known as a typical photocatalyst that exhibits photocatalytic action by ultraviolet rays, and can be suitably used in the present invention. In order to form the photocatalytic coating 3 of titanium dioxide, it is preferable to use a sol-gel method. Specifically, first, a starting material is prepared by adding an amount of water necessary for hydrolysis and nitric acid as a catalyst to a solution obtained by adding an alcohol to a titanium alkoxide solution. Next, the starting material is stirred at a constant temperature to cause hydrolysis and polycondensation reaction to produce fine particles composed of titanium hydroxide to prepare a titania sol. Next, the obtained titania sol is coated on the pattern forming surface of the translucent substrate 1, or the titania sol is coated by dipping the pattern forming surface of the translucent substrate 1 in the titania sol and pulling it up. And the photocatalyst film 3 is formed into a film by drying and baking. The photocatalyst film 3 obtained by this sol-gel method is substantially made of only titanium dioxide and can be formed relatively thick. Therefore, the film strength and durability are excellent, and the photocatalytic action can be efficiently expressed.

  Further, the photocatalytic coating 3 consisting essentially of titanium dioxide can also be formed by a reactive sputtering method using a titanium metal target, a method of sputtering a titanium dioxide ceramic target, a CVD method, or the like.

  Further, a slurry obtained by dispersing titanium dioxide powder in a dispersion medium obtained by adding an organic binder or an inorganic binder to water may be applied and dried. In order to increase the surface area and enhance the photocatalytic action, the titanium dioxide powder is preferably as fine as possible within a range where it can be uniformly dispersed. This method is simple, and spray coating is possible when the binder concentration of the dispersion medium is low. However, the obtained photowork plate film 3 has insufficient film strength and durability, and only titanium dioxide exposed on the surface of the photocatalyst film 3 exhibits a photocatalytic action, so that the efficiency is inferior. is there.

  As photocatalysts other than titanium dioxide, zinc oxide, tungsten oxide, cadmium oxide, indium oxide, silver oxide, manganese oxide, copper oxide, iron oxide, tin oxide, vanadium oxide, niobium oxide and other metal oxides, cadmium sulfide, sulfide Metal sulfides such as zinc, indium sulfide, lead sulfide, copper sulfide, molybdenum sulfide, tungsten sulfide, antimony sulfide, and bismuth sulfide, or a mixture of these metal oxides and metal sulfides can be suitably used. These photocatalysts can also be formed by a sol-gel method, a sputtering method, a CVD method, or slurry application. Moreover, the mixture of these photocatalysts and titanium dioxide may be sufficient.

  Proximity exposure can be performed in the same manner as in the past using a photomask having the photocatalyst film 3 formed thereon. That is, as shown in FIG. 1, a photomask having a photocatalytic film 3 formed thereon. The substrate 10 provided with the resist film 11 is disposed with a predetermined gap so that the photocatalyst film 3 and the resist film 11 face each other, and is exposed by irradiating ultraviolet rays. Exposure conditions such as ultraviolet intensity and exposure time may be the same as in the past. Even if a sublimate is generated from the resist film 11 by the ultraviolet irradiation, the sublimate adheres to the photocatalyst film 3, and thus the attached sublimate is decomposed by the photocatalytic action at the next exposure. Therefore, by using the photomask of the present invention, the number of exposures until mask replacement can be greatly increased, and productivity can be increased. Moreover, since the photocatalytic action increases as the irradiation intensity of ultraviolet rays increases, the exposure time can be shortened, and the productivity can be further improved.

  The exposure apparatus may be a conventional one, and there is no limitation as long as the photomask on which the photocatalyst film 3 is formed can be mounted.

It is a schematic diagram which shows an example of the photomask for close exposure of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Translucent board | substrate 2 Pattern 3 Photocatalyst film 10 Board | substrate 11 Resist film

Claims (3)

  A proximity exposure photomask in which a pattern made of a light-shielding material is formed on a light-transmitting substrate, comprising a coating made of a photocatalyst that exhibits a photocatalytic action by exposure light on the surface on which the pattern is formed or the photocatalyst A photomask for proximity exposure, wherein a film is formed.   An exposure method comprising performing proximity exposure using the photomask for proximity exposure according to claim 1.   An exposure apparatus comprising: a photomask for proximity exposure according to claim 1 for performing exposure.

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