Bottom anti-reflective coating material composition for...

Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making

Reexamination Certificate

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C430S281100, C430S286100, C430S338000

Reexamination Certificate

active

06399269

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a composition of a bottom anti-reflective coating material for a photoresist capable of forming a bottom anti-reflective coating which is effective in reducing an adverse effect of reflection from a background substrate in a lithography process using various radiations, and to a method of forming a resist pattern using the composition of a bottom anti-reflective coating material.
BACKGROUND OF THE INVENTION
A photoresist is coated on a substrate such as semiconductor wafer, glass, ceramic or metal to have a thickness of from 0.5 to 2 &mgr;m by a spin coating method or a roller coating method and thereafter subjected to heating, drying, printing of a circuit pattern through an exposure mask with radiation such as ultraviolet ray, post exposure baking if desired, and development to form an image.
Etching is conducted using the image as a mask so as to effect pattern working on a substrate. Representative examples of the application field thereof include production process of semiconductors such as IC, production of circuit substrates such as liquid crystal and thermal head and other photofabrication process.
In the semiconductor fine working using a photoresist, accompanying the tendency towards finer dimensions, a matter of great importance is the prevention of light reflection from the substrate. For this purpose, a photoresist containing a light absorbent has been conventionally used. However, the use has a problem in that the resolution is impaired. Accordingly, a method of providing a bottom anti-reflective coating (BARC) between the photoresist and the substrate has been extensively investigated. Known examples of the bottom anti-reflective coating include an inorganic coating type such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon and &agr;-silicon, and an organic coating type comprising a light absorbent and a polymer material.
The former requires equipments such as a vacuum evaporation apparatus, a CVD apparatus and a sputtering apparatus, for the coating formation. The latter is advantageous since it does not require any particular equipment, and a large number of investigations have been made thereon.
For example, JP-B-7-69611 (the term “JP-B” as used herein means an “examined Japanese patent publication”) describes a coating comprising a condensate of a diphenylamine derivative with a formaldehyde-modified melamine resin, an alkali-soluble resin and a light absorbent, U.S. Pat. No. 5,294,680 describes a reaction product of a maleic anhydride copolymer with a diamine-type light absorbent, JP-A-6-118631 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) describes a coating comprising a resin binder and a methylolmelamine-base heat cross-linking agent, JP-A-6-118656 describes an acrylic resin-type anti-reflective coating containing within the same molecule a carboxylic acid group, an epoxy group and a light absorbing group, JP-A-8-87115 describes a coating comprising methylolmelamine and a benzophenone-base light absorbent, and JP-A-8-179509 describes a coating obtained by adding a low molecular light absorbent to a polyvinyl alcohol resin.
The material for organic bottom anti-reflective coating preferably has physical properties such that it exhibits a large absorbance to radiations, it is insoluble in a photoresist solvent (not to cause intermixing with a photoresist layer), it is free from diffusion of a low molecular substance from the anti-reflective coating material to the overcoat photoresist layer during the coating or drying with heating, and it has a high dry etching rate as compared with the photoresist. These are also described, for example, in
Proc. SPIE,
Vol. 2195, 225-229 (1994).
Recently, from a standpoint of the rationalization of production process, it has been desired to use a common solvent for coating the bottom anti-reflective coating composition and the resist composition. Thus, an attempt of adding to the bottom anti-reflective coating composition a compound which causes a crosslinking reaction by heating and hardens the coating to prevent the occurrence of intermixing with the resist layer has been made as described, for example, in JP-A-6-118631 and U.S. Pat. No. 5,693,691.
However, the compounds described in the above-described patents fail to satisfy all these requirements and improvements have been demanded. For example, some conventional bottom anti-reflective coatings are insufficient in the light absorbing power of the binder and require separate loading of a light absorbent, and some contain a large amount of an aromatic light absorbent for increasing the absorbance have a problem of the occurrence of intermixing with the resist layer through interface of the light absorbent. Further, those having, in the crosslinking system, a functional group capable of increasing alkali permeability such as a carboxylic acid group, are accompanied by a problem in that when development with an alkaline aqueous solution is performed, the anti-reflective coating swells to incur deterioration of a resist pattern shape.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a bottom anti-reflective coating material composition for a photoresist, which is capable of forming a bottom anti-reflective coating having a large absorbance to light including a wavelength used for exposure, which does not cause intermixing with a photoresist, and which can reduce an adverse effect due to a standing wave generated by reflection from a substrate.
Another object of the present invention is to provide a bottom anti-reflective coating material composition for a photoresist, which is capable of forming a bottom anti-reflective coating that can increase a limiting resolution of the photoresist and provide a good resist profile.
A further object of the present invention is to provide a method of forming a resist pattern, which is capable of forming an excellent resist pattern.
Other objects of the present invention will become apparent from the following description.
These objects of the present invention are accomplished with the bottom anti-reflective coating material composition for a photoresist and method of forming a resist pattern described below.
(1) a bottom anti-reflective coating material composition for a photoresist comprising the following components (a) to (d):
(a) a polymer containing a dye structure having a molar extinction coefficient of 1.0×10
4
or more to light including a wavelength used for exposure of the photoresist;
(b) a thermal crosslinking agent which is activated by an acid to react with component (a) described above, thereby forming a crosslinked structure;
(c) a sulfonic acid ester compound or diaryl iodonium salt, which is decomposed to generate an acid with heating at temperature between 150 to 200° C.; and
(d) an organic solvent capable of dissolving components (a) to (c) described above;
(2) a bottom anti-reflective coating material composition for a photoresist as described in item (1) above, wherein the polymer of component (a) has a glass transition temperature of from 80 to 180° C.;
(3) a bottom anti-reflective coating material composition for a photoresist as described in item (1) or (2) above, wherein the polymer of component (a) contains a repeating unit having the dye structure in an amount of 10% by weight or more;
(4) a bottom anti-reflective coating material composition for a photoresist as described in any one of items (1) to (3) above, wherein the dye structure in the polymer of component (a) is a structure represented by the following formula (I) or (II);
wherein W represents a linking group to the polymer main chain; Y represents an oxygen atom, a sulfur atom or ═N—V; Z
1
and Z
2
, which may be the same or different, each represents an electron donating group; m and n represent an integer of from 0 to 2 and from 0 to 3, respectively, and when m and n each is 2 or 3, the Z
1
groups or Z
2
groups may be the same or different; and V represents a hydroxy gro

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