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
2001-08-07
2004-09-07
Huff, Mark F. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S326000, C430S271100, C430S272100, C430S905000, C430S914000
Reexamination Certificate
active
06787284
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a positive resist composition and a base material carrying a resist layer composed of the positive resist composition.
2. Description of the Related Art
Semiconductor devices are more and more being intensified in the degree of integration in recent years. The mass production of large-scale integrated circuits (LSIs) using 0.18-&mgr;m design rules had been already launched, and the mass production of LSIs using 0.15-&mgr;m design rules was launched at the end of 2000.
In the lithography process for such semiconductors, attempts are made to put LSIs using about 0.13-&mgr;m design rules into practical use. Such attempts include the use of a chemically amplified positive or negative resist as the resist; the combination use of the chemically amplified positive or negative resist with an organic or inorganic anti-reflection coating; improvements in exposure mask such as the use of a half-tone mask and Levenson mask; and improvements in exposure equipment such as annular illumination, scanning technique, and the use of lenses with higher numerical apertures.
A silicon-containing resist is one of hopeful candidates for use in next-generation or next-to-next-generation lithography processes using 0.15-&mgr;m or shorter design rules. Such silicon-containing resists have satisfactory dry etching resistance and have been widely reported.
For example, Japanese Patent Laid-Open Nos. 8-334900, 8-334901 and 9-87391 propose chemically amplified positive resist compositions each comprising an acid generator, and a polysiloxane in which part of hydrogen atoms of hydroxyl groups in polyhydroxybenzylsilsesquioxane is protected with an acid-unstable group.
However, such binary system positive resists comprising polyhydroxybenzylsilsesquioxane having an acid-unstable group in combination with an acid generator are not satisfactory in definition and resist pattern shape and should be improved.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a positive resist composition that is useful in processes using F
2
excimer laser (157 nm), extreme-ultraviolet rays (EUV, vacuum ultraviolet rays; 13 nm) and other light sources having wavelengths equal to or shorter than that of KrF excimer laser, and has high definition and can form resist patterns with good sectional shapes, as well as to provide a base material carrying a resist layer composed of the positive resist composition.
Specifically, the present invention provides, in an aspect, a positive resist composition including (A) an alkali-soluble polysiloxane resin, (B) an acid generator composed of a compound which generates an acid upon irradiation of active light or radiant ray, and (C) a compound in which at least one hydrogen atom of phenolic hydroxyl group or carboxyl group is substituted with an acid-decomposable group.
In the positive resist composition, Ingredient (A) is preferably an alkali-soluble polysiloxane resin including (a1) a siloxane unit containing an alkali-soluble group, and (a2) a siloxane unit containing an alkali-insoluble group, which alkali-insoluble group has no acid-decomposable group.
More preferably, the alkali-soluble group of the siloxane unit (a1) is at least one of hydroxyl group and carboxyl group.
In the siloxane unit (a1), the alkali-soluble group is preferably bonded to the silicon atom of a siloxane group through at least one group selected from among alkylene groups, cycloalkylene groups and aralkylene groups.
The siloxane unit (a1) is more preferably a hydroxybenzylsilsesquioxane unit.
The alkali-insoluble group having no acid-decomposable group of the siloxane unit (a2) is preferably at least one selected from among alkyl groups, cycloalkyl groups, aryl groups and aralkyl groups.
The siloxane unit (a2) is more preferably a phenylsilsesquioxane unit.
Preferably, Ingredient (C) in the positive resist composition is a compound in which at least one hydrogen atom of the hydroxyl group or carboxyl group of a compound of following Formula (I) is substituted with an acid-decomposable group, which acid-decomposable group is selected from among tertiary-alkyloxycarbonyl-substituted alkyl groups, tertiary-alkyloxycarbonyl groups, tertiary-alkyl groups, cyclic ether groups and alkoxy-substituted alkyl groups:
wherein Z is a hydroxyl group or a carboxyl group; each of R
1
, R
2
and R
3
is independently a hydrogen atom, a hydroxyl group, a halogen atom, an alkoxy group having from 1 to 5 carbon atoms, or a linear, branched or cyclic alkyl group having from 1 to 6 carbon atoms; A is a single bond or a divalent organic group selected from the group consisting of alkylene groups each having from 1 to 5 carbon atoms, alkylidene groups each having from 2 to 5 carbon atoms, alkylene groups each having from 1 to 5 carbon atoms and further having a carboxyl group, alkylidene groups each having from 2 to 5 carbon atoms and further having a carboxyl group, a carbonyl group, and groups of the following formulae:
R
4
is a hydrogen atom or an alkyl group having from 1 to 5 carbon atoms; each of R
5
and R
6
is independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms; each of R
7
and R
8
is independently an alkyl group having from 1 to 5 carbon atoms; each of R
9
and R
10
is independently a hydrogen atom, a hydroxyl group or an alkyl group having from 1 to 5 carbon atoms; and m denotes an integer from 1 to 6.
The acid-decomposable group in the positive resist composition is preferably at least one selected from among tert-butyloxycarbonylmethyl group, tert-butyloxycarbonyl group, tert-butyl group, tetrahydrofuranyl group, tetrahydropyranyl group, ethoxyethyl group and methoxypropyl group.
In another aspect, the present invention provides a base material including an organic polymer layer as a first resist layer formed on a substrate, and a second resist layer formed on the organic polymer layer, which second resist layer is composed of the positive resist composition and has a thickness of from 50 to 200 nm.
DETAILED DESCRIPTION OF THE INVENTION
Ingredient (A)
Ingredient (A) for use in the present invention is an alkali-soluble polysiloxane resin. Such alkali-soluble polysiloxane resins as Ingredients (A) are not specifically limited as far as they each have a phenolic hydroxyl group or carboxyl group which is conducive to alkali-solubility and have a siloxane skeleton which is conducive to dry etching resistance.
Among them, preferred Ingredients (A) for use in the present invention are alkali-soluble polysiloxane resins having (a1) a siloxane unit containing an alkali-soluble group and (a2) a siloxane unit containing an alkali-insoluble group, which alkali-insoluble group has no acid-decomposable group. These alkali-soluble polysiloxane resins are highly soluble in alkali in exposed portions and are highly insoluble in alkali in unexposed portions and exhibit higher contrast and satisfactory definition and can form resist patterns with good shapes.
Additionally, these alkali-soluble polysiloxane resins have improved transparency to F
2
excimer laser and can form resist patterns with high definition upon the use of F
2
excimer laser.
In the siloxane unit (a1), the alkali-soluble group (e.g., a phenolic hydroxyl group or carboxyl group) is preferably bonded to the silicon atom of the siloxane group through a divalent organic group. Such divalent organic groups include, for example, alkylene groups each having from 1 to 10 carbon atoms, cycloalkylene groups each having from 5 to 8 carbon atoms, and aralkylene groups each having from 7 to 12 carbon atoms, of which aralkylene groups are typically preferred.
As the siloxane group, a silsesquioxane unit represented by the formula: —SiO
3/2
— is preferred, since the resulting resist composition can form a dense or tight film or coating and exhibits satisfactory dry etching resistance.
Examples of the siloxane units (a1) for use herein are as follows.
O
Endo Koutaro
Komano Hiroshi
Ogata Toshiyuki
Huff Mark F.
Lee Sin J.
Tokyo Ohka Kogyo Co. Ltd.
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