Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2001-05-24
2002-11-05
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S192000, C430S193000, C430S270100
Reexamination Certificate
active
06475694
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a positive photoresist composition. Specifically, it relates to a positive photoresist composition that is excellent in focal depth range (depth of focus: DOF) properties and has a high sensitivity in a photolithographic process in which a fine pattern of about 0.35 &mgr;m is formed using i-ray (365 nm).
2. Description of the Related Art
Photoresists comprising an alkali-soluble resin and a quinonediazido-group-containing compound are excellent in definition, sensitivity and etch resistance in the photolithographic process using i-ray (365 nm) and have been practically sufficiently used in the manufacture of semiconductor devices and liquid crystal devices.
Conventionally, it has been believed that a fine pattern of a size smaller than the wavelength of light used for exposure cannot be formed, but improvement in materials, process conditions and exposure techniques achieves the formation of a fine pattern of a size of about 0.35 &mgr;m which is less than the wavelength of i-ray.
However, both a high definition and a high sensitivity cannot be obtained concurrently, and a high definition resist tends to be low in sensitivity and is not sufficient in DOF properties. Accordingly, such a high definition resist has deteriorated yield or throughput.
Japanese Patent Laid-Open No. 5-107755 (Reference 1) discloses, as a highly sensitive positive photoresist composition, a material composed of an alkali-soluble resin, a naphthoquinonediazide derivative having an acid-decomposable group and a naphthoquinonediazidosulfonyl group, and an acid-generator which generates an acid upon irradiation with active light or radiant ray.
A compound represented by the following Formula (III) is listed as the naphthoquinonediazide derivative, but the resulting composition only achieves a definition of about 0.7 &mgr;m.
Japanese Patent Laid-Open No. 8-262713 (Reference 2) discloses, as a positive photoresist composition which is highly sensitive in the deep UV region, a material composed of an alkali-soluble resin, a polyhydroxystyrene-based polymeric substance having an acid-decomposable group and a naphthoquinonediazidosulfonyl group, and an acid-generator which generates an acid upon absorption of light.
Investigations have been made on KrF-, ArF- and other excimer laser light sources as light sources which emit light in the deep UV region, but these light sources require a very expensive aligner (stepper) as compared with that in i-ray light source, inviting higher production costs of semiconductors. Additionally, this material only achieves a definition of about 4 &mgr;m.
Japanese Patent Laid-Open No. 11-95424 (Reference 3) discloses a material composed of an alkali-soluble resin, a compound having an acid-decomposable group and a naphthoquinonediazidosulfonyl group, and a compound which generates an acid upon irradiation with light having a wavelength less than 300 nm, as a positive photoresist composition which can form a pattern both upon irradiation with i-ray and upon irradiation with deep UV.
A compound represented by the following Formula (IV) is listed as the compound having an acid-decomposable group and a naphthoquinonediazidosulfonyl group, but the resulting resist composition cannot exhibit a high sensitivity in photolithographic process using i-ray:
wherein D′ is a 1,2-naphthoquinonediazidosulfonyl group; R′ is an acid-decomposable group; each of R is, for example, independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group; and X is CO or SO
2
.
Japanese Patent Laid-Open No. 6-167805 (Reference 4) discloses a material composed of a quinonediazide ester having a linear tetra- to hepta-nuclear polyphenol skeleton as a photosensitive ingredient, as a high-definition positive photoresist composition.
This material can form a pattern of a size of about 0.35 &mgr;m with a good shape, but a higher sensitivity is desired.
Additionally, the DOF properties of this material are only evaluated in 0.45-&mgr;m line-and-space (L&S) pattern, and no evaluation is made in the formation of an ultrafine pattern of about 0.35 &mgr;m.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a positive photoresist composition that can form a fine pattern of about 0.35 &mgr;m in a photolithographic process using i-ray (365 nm), is excellent in DOF properties in such an ultrafine region and has a higher sensitivity.
The present inventors found that the dissolving rates of exposed portions of a photoresist composition in an alkali developer can be markedly improved, while maintaining a high definition, by the use of an acid-generator activated by i-ray (365 nm) and by capping of phenolic hydroxyl groups in an alkali-soluble resin with an acid-decomposable group which is decomposed by action of the generated acid.
They also found that the dissolving rates of exposed portions of a photoresist composition in an alkali developer can be markedly improved, while maintaining a high definition, by the use of an acid-generator activated by i-ray (365 nm) and by capping of phenolic hydroxyl groups in a quinonediazide ester having a specific structure with an acid-decomposable group which is decomposed by action of the generated acid.
Specifically, the present invention provides, in an aspect, a positive photoresist composition including (A) an alkali-soluble resin in which part of phenolic hydroxyl groups is protected by an acid-decomposable group; (B) a quinonediazide ester; and (C) a compound which generates an acid upon irradiation of light with a wavelength of 365 nm.
In another aspect, the present invention provides a positive photoresist composition which includes (A) an alkali-soluble resin; (B) a quinonediazide ester represented by the following Formula (I):
wherein each of R
1
to R
8
is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a cycloalkyl group; each of R
9
to R
11
is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; Q is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or Q is combined with R
9
to form a cyclic ring having 3 to 6 carbon atom members, or a residue represented by the following Formula (II):
wherein each of R
12
and R
13
is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a cycloalkyl group; and c denotes an integer of 1 to 3; each of D is independently a hydrogen atom, a 1,2-naphthoquinonediazidosulfonyl group or an acid-decomposable group, where at least one of D is a 1,2-naphthoquinonediazidosulfonyl group and at least one of D is an acid-decomposable group; each of a and b denotes an integer of 1 to 3; d denotes an integer of 0 to 3; and n denotes an integer of 0 to 3; and (C) a compound which generates an acid upon irradiation of light with a wavelength of 365 nm.
Preferably, part of phenolic hydroxyl groups in Ingredient (A) in the aforementioned positive photoresist composition is protected by an acid-decomposable group.
In the positive photoresist composition, a quinonediazide ester represented by the following Formula (I-a) may be contained as Ingredient (B):
wherein R
1
to R
8
, D, a, b and d have the same meanings as defined above; and m denotes an integer of 1 to 3.
Alternatively, a quinonediazide ester represented by the following Formula (I-b) may be contained as Ingredient (B):
wherein R
1
to R
6
, R
12
, R
13
, D, a, b and c have the same meanings as defined above.
In the invented positive photoresist composition, the acid-decomposable group may be a group represented by the following Structural Formula (a-1):
Alternatively, the acid-decomposable group may be a group represented by the following Structural Formula (a-2):
From 5% to 50% of the total phenolic hydroxyl groups of Ingredient (A) in the positive photoresist composition may be protected by an acid-decomposable group.
Alternatively, from 1
Doi Kousuke
Hirata Atsuko
Kohara Hidekatsu
Miyagi Ken
Nakayama Toshimasa
Chu John S.
Sughrue & Mion, PLLC
Tokyo Ohka Kogyo Co. Ltd.
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