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
2000-08-10
2003-01-28
Ashton, Rosemary (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
C430S914000, C430S921000, C430S927000
Reexamination Certificate
active
06511783
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a negative resist composition suitably used in an ultramicrolithography process or another photofabrication process for the production of very large-scale integrated circuits or high capacity microchips. More particularly, the invention relates to a negative resist composition which can form highly miniaturized patterns by use of X-rays or electron beams including excimer laser beams, and especially to a negative resist composition which can be suitably used in miniaturization processing of semiconductor elements by use of high energy beams such as electron beams.
BACKGROUND OF THE INVENTION
Integrated circuits have been progressively increased in their integration degree, and therefore processing of ultra-micro patterns having a line width of a half micron or less has become necessary in the production of semiconductor substrates for very large-scale integrated circuits. For fulfilling this necessity, the wavelength of light used in an exposure apparatus employed for photolithography becomes progressively shorter, and now, far ultraviolet light and excimer laser light (such as XeCl, KrF or ArF) has been studied. Further, the formation of more micro patterns with electron beams or X-rays has been studied.
In particular, electron beams or X-rays are placed as next or next-next generation technology of pattern formation, and the development of negative resists which can attain high sensitivity, high resolution and rectangular profile shape has been desired.
Electron beam lithography is technology in which accelerated electron beams emit energy in the course of colliding with atoms constituting resist materials to cause scattering, thereby exposing the resist materials. The use of highly accelerated electron beams increases the rectilinear propagation and reduces the influence of electron scattering, which makes it possible to form rectangular patterns having high resolution. On the other hand, it increases the permeability of electron beams, resulting in lowered sensitivity. As described above, in the electron beam lithography, there is the trade-off relationship between the sensitivity and the resolution/resist shape, and it has been a problem how to allow them to be compatible with each other. With respect to chemical amplification type negative resists, various acid generators have hitherto been proposed. JP-B-8-3635 (the term “JP-B” as used herein means an “examined Japanese patent publication”) discloses organic halogen compounds, JP-A-2-150848 (the term “JP-A” as used herein means an “unexamined published Japanese patent application) and JP-A-6-199770 disclose iodonium salts and sulfonium salts, JP-A-2-52348, JP-A-4-367864 and JP-A-4-367865 disclose acid generators containing Cl or Br, JP-A-4-210960 and JP-A-4-217249 disclose diazodisulfone and diazosulfone compounds, JP-A-4-226454 discloses triazine compounds, and JP-A-3-87746, JP-A-4-291259, JP-A-6-236024 and U.S. Pat. No. 5,344,742 disclose sulfonate compounds. However, these acid generators have failed to overcome the trade-off relationship between the sensitivity and the resolution/resist shape under irradiation of electron beams.
As to crosslinking agents, methylolmelamine, resol resins, epoxidated novolak resins and urea resins have hitherto been used. However, these crosslinking agents are unstable to heat, so that they have a problem with regard to storage stability when used in resist solutions. Further, they have failed to satisfy required characteristics of high sensitivity, high resolution and rectangular resist shape under irradiation of electron beams.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to solve the problems in respect to techniques for improving the original performance of the micro photofabrication using electron beams, and to develop chemical amplification system negative resist compositions for electron beams or X-rays satisfying the characteristics of sensitivity and resolution/resist shape to the use of the electron beams or the X-rays.
As a result of intensive studies, the present inventors have known that the above-mentioned various objects of the invention are attained by using specific photoacid generators and/or specific crosslinking agents, depending on the type of photosensitive composition, thus completing the invention.
That is to say, these and other objects of the invention are attained by the following:
(1) A chemical amplification system negative resist composition for an electron beam and/or an X-ray comprising an alkali-soluble resin, a radiation-sensitive acid generator and a crosslinking agent which initiates crosslinking by an acid, wherein the crosslinking agent is a phenol derivative having 3 to 5 benzene ring atomic groups in a molecule, having a molecular weight of 1,200 or less, and having two or more hydroxymethyl and/or alkoxymethyl groups in all in the molecule, the groups being combined with at least any of the benzene ring atomic groups;
(2) The negative resist composition according to claim 1, wherein the radiation-sensitive acid generator is a compound represented by any one of the following general formulas (I) to (III):
wherein R
1
to R
37
each represents a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, a halogen atom or a group represented by —S—R
38
wherein R
38
represents an alkyl group or an aryl group; R
1
to R
38
may be the same or different; two or more selected from R
1
to R
15
may be combined with each other directly at their ends, or through an atom selected from oxygen, sulfur and nitrogen to form a ring structure; R
16
to R
27
may also form a ring structure similarly; R
28
to R
37
may also form a ring structure similarly; X
−
is an anion of an acid, which is selected from benzenesulfonic acid, naphthalene-sulfonic acid and anthracenesulfonic acid; the acid is substituted by a fluorine atom, and has at least one organic group selected from the group consisting of an alkyl group, an alkoxyl group, an acyl group, an acyloxy group, a sulfonyl group, a sulfonyloxy group, a sulfonylamino group, an aryl group, an aralkyl group and an alkoxycarbonyl group; and moreover, the organic group is further substituted by at least one fluorine atom; and
(3) The negative resist composition according to claim 2, wherein each of the alkyl group and the alkoxyl group is any one of straight-chain, branched or cyclic groups.
Embodiments of the negative resist compositions of the invention include (1) and (2) described below:
(1) A negative resist composition comprising an alkali-soluble resin, a radiation-sensitive acid generator and a crosslinking agent, in which the crosslinking agent is a phenol derivative having 3 to 5 benzene ring atomic groups in a molecule, having a molecular weight of 1,200 or less, and having two or more hydroxymethyl and/or alkoxymethyl groups in all in the molecule, the groups being combined with at least any of the benzene ring atomic groups, and initiates crosslinking by an acid; and
(2) A negative resist composition comprising an alkali-soluble resin, a radiation-sensitive acid generator represented by any one of general formulas (I) to (III) and a crosslinking agent, in which the crosslinking agent is a phenol derivative having 3 to 5 benzene ring atomic groups in a molecule, having a molecular weight of 1,200 or less, and having two or more hydroxymethyl and/or alkoxymethyl groups in all in the molecule, the groups being combined with at least any of the benzene ring atomic groups, and initiates crosslinking by an acid.
In the invention, of the above-mentioned embodiments (1) and (2), the embodiment (1) is preferred in that the effects of the invention are achieved more significantly.
DETAILED DESCRIPTION OF THE INVENTION
The compounds used in the invention are described below:
(1) Alkali-Soluble Resins Used in the Invention
In the invention, the alkali-soluble resins are used together with the radiation-sensitive acid generators. Examples of the alkali-soluble resins used together with the radiation-sensitive acid genera
Ashton Rosemary
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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