Loading patent…
AssigneeHoya Corporation
InventorsHideo Kobayashi, Keishi Asakawa
Estimating the term…
In a method of producing a photomask blank, comprising a thin film forming step of forming, on a rectangular substrate, a thin film for causing an optical change in exposure light, a resist application step of applying a positive resist on the thin film, a baking step of heat treating the resist applied on the thin film, and a removing step of removing a resist film formed in a portion of the edge of the substrate, the removing step is carried out by exposing the resist film in the portion of the edge of the substrate after the resist application step and before the heat treating step so that, upon development subsequently carried out in the removing step, a difference in solubility or dissolving speed in a developer is obtained between an exposed area and an unexposed area and by selectively supplying the developer to the exposed area.
A method of producing a photomask blank, comprising a thin film forming step of forming, on a rectangular substrate, a thin film for causing an optical change in exposure light, a resist application step of applying a positive resist on said thin film, a baking step of heat treating said resist applied on said thin film, and a removing step of removing a resist film formed in a portion of an edge of said substrate, wherein said removing step is carried out by exposing said resist film in said portion of the edge of said substrate after said resist application step and before said baking step so that, upon development subsequently carried out in said removing step, a difference in solubility or dissolving speed in a developer is obtained between an exposed area and an unexposed area and by selectively supplying said developer to said exposed area.
A method of producing a photomask blank, comprising a thin film forming step of forming, on a rectangular substrate, a thin film for causing an optical change in exposure light, a resist application step of applying a positive resist on said thin film, and a baking step of heat treating said resist applied on said thin film, wherein said resist film in said portion of the edge of said substrate is exposed after said resist application step and before said baking step so that, in a developing step during a photomask production process, said resist film in said portion of the edge of said substrate exposed as mentioned above is removed simultaneously with formation of a mask pattern.
An unnecessary film removing apparatus for removing, from a positive resist film formed on a surface of a photomask blank, an unnecessary part formed in a portion of an edge of said substrate as an unnecessary film, said apparatus comprising:
A photomask blank producing apparatus comprising a resist application apparatus for applying a positive resist on a surface of a photomask blank including a rectangular substrate and a thin film formed on said substrate for causing an optical change in exposure light, and an unnecessary film removing apparatus described in any one of structures 7 through 11, said unnecessary film removing apparatus being arranged so that said exposure means, said removing means, and said baking means are disposed in this order along a conveying line of said photomask blank.
A photomask blank producing apparatus comprising a resist application apparatus for applying a positive resist on a surface of a photomask blank including a rectangular substrate and a thin film formed on said substrate for causing an optical change in exposure light, and an unnecessary film removing apparatus described in any one of structures 7 through 11, said unnecessary film removing apparatus being arranged so that said exposure means, said baking means, and said removing means are disposed in this order from an upstream side towards a downstream side along a conveying line of said photomask blank.
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
From the US filing history. Foreign family members aren’t listed.
Backward citations are indexed for grants only.
For the removal of unwanted material, e.g. image or background correction: of an edge bead on wafers
Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles…
Photomechanical production of textured or patterned surfaces
Term end not estimated
This invention relates to a method and an apparatus for producing a photomask blank (hereinafter may simply be referred to as a mask blank) used to obtain a photomask (including a reticle) and including a transparent substrate on which a phase shift film, an opaque film, or a stack of the phase shift film and the opaque film is formed, and a resist applied thereon. This invention particularly relates to a method and an apparatus for producing a photomask blank from which an unnecessary film, i.e., an unnecessary part of a resist film is removed, which is formed in a peripheral portion or a portion of the edge of a substrate as a result of resist application. This invention also relates to an apparatus for removing the unnecessary portion of a film.
In the lithography technology as a method of producing a semiconductor device (such as LSI), a photomask (including a reticle) is used for transfer of circuit patterns. In order to produce the mask, a blank is used as a material. Referring to FIG. 1, the blank depicted at 5 in the figure is obtained in the following manner. On a transparent substrate 1 made of synthetic quartz or the like, an opaque film 2 made of chromium as a main component is formed on the transparent substrate 1. Then, an antireflection film 3 made of chromium oxide as a main component is continuously or discontinuously formed on the opaque film 2 by sputtering or the like. Thereafter, a resist is applied onto the antireflection film 3 by spin coating or the like, followed by heat treatment (post-application bake (pre-bake or soft bake)) for drying up to thereby form a resist film 4.
When the resist is applied as mentioned above, a relatively thick resist part 6 is formed in a portion of the edge of a substrate (i.e., a zone along four sides of a principal surface of the substrate 1 and an end face (side surface) of the substrate 1), as shown in FIG. 2 which is an enlarged view of an encircled part A in FIG. 1.
FIG. 1 is a view for describing a typical process of producing a blank;
FIG. 2 is an enlarged view of an encircled part in FIG. 1;
FIG. 3 is a view showing a surface of a substrate from which an unnecessary resist film is removed by an organic solvent;
Now, this invention will be described in detail.
From the study of the present inventors, it has been found out that, simply by introducing post-application exposure, selective solubility (solubility difference or difference in dissolving speed) between an exposed area and an unexposed area is assured in a developing/removing step even in case of a positive chemically-amplified (CA) resist. The post-application exposure is an operation of selectively exposing an unnecessary resist film after the resist is applied and before post-application bake (prebake or soft bake) is carried out. Specifically, even if post-exposure bake (PEB), which is presently believed essential for the chemically-amplified resist, is not carried out, it is possible to remove the unnecessary resist film by development. Thus, it has been found out that a step or a mechanism for carrying out the post-exposure bake independent of the post-application bake is no longer necessary.
In case of the chemically-amplified resist, this invention is advantageous in the following respect. As illustrated in FIG. 4, the above-mentioned fourth existing method of removing an unnecessary resist in a portion of the edge of a substrate by the use of a typical process of treating the chemically-amplified resist requires a resist application step or mechanism, a post-application bake step or mechanism, an exposure step or mechanism for selectively exposing the unnecessary resist film in the portion of the edge of the substrate (periphery exposure), a post-exposure bake (PEB) step or mechanism, and a developing/removing step or mechanism. On the other hand, this invention does not require the post-exposure bake step or mechanism. It is therefore possible to achieve simplification in process steps and apparatus arrangement and to reduce the production cost, as compared with the fourth existing method.