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
2000-01-14
2002-05-07
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
Reexamination Certificate
active
06383713
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a chemical amplification type positive resist composition of usable in the fine processing in the production of semiconductor.
The fine processing in the production of semiconductor has usually been performed by adopting the lithography process using a resist composition. In the lithography process, principally, resolution can be improved by shortening wavelength for exposure, as indicated by the Rayleigh's equation for limit of diffraction. Accordingly, the wavelength of the light source for a lithography process used in the production of semiconductors has become shorter and shorter in such order of a g-ray at a wavelength of 436 nm, an i-ray at a wavelength of 365 nm, and a KrF excimer laser at a wavelength of 248 nm. The ArP excimer laser at a wavelength of 193 nm is expected the next generation light source.
Since lenses in exposing machines using an ArF excimer laser have a shorter lifetime as compared with the lenses for the conventional exposing light source, a shorter time period for exposing such lenses to ArF excimer laser rays preferred. In order to make the exposure time shorter, the sensitivity of the resists is to be increased, and for such purpose, so called chemical amplification type resists are used. The-chemical amplification type resist contains a resin having a group cleavable by the action of an acid, and utilizes a catalytic action of the acid generated by exposure to the ray.
It has been known that resins used in resists to be exposed to ArF excimer lasers preferably have no aromatic ring in order to insure the transmittance of the resists and have an alicyclic ring in place of an aromatic ring in order to confer a dry etching resistance. Various resins have been known as resins meeting such requirements. For example, D. C. Hofer, J. Photopolym. Sci. Technol., Vol. 9, No. 3, pages 387-398 (1996) describes much resins. The known resins, however, have a problem that peeling on development is liable to occur due to insufficient adherence during development, particularly when the polarity is not sufficient.
S. Takechi et al., J. Photopolym. Sci. Technol., Vol. 9, No. 3, pages 475-487 (1996) and JP-A-9-73173 describe that, when polymers or copolymers of 2-methyl-2-adamantyl methacrylate are used as resins for a chemical amplification type resist, a positive working action is realized by cleavage of the 2-methyl-2-adamantyl group by the action of an acid and a high dry etching resistance, high resolution and a good adherence to substrate are obtained. JP-A-10-274852 describes that the adherence to substrate is improved by using a resin having a butyrolactone residue in a part of the polymerization units, as a resin composing a chemical amplification type positive resist composition. In addition, JP-A-10-319595 describes a positive resist composition using a resin having a carboxyl group protected by a &ggr;-butyrolactone-3-yl residue.
On the other hand, since the chemical amplification type resists utilizes the action of an acid, the profiles are liable to be bottom-tailed by deactivation of the acid when the substrate is of a basic nature. It is known that this problem can be resolved by adding a large amount of a basic quencher substance. Addition of a large amount of such quencher substance, however, results in decrease of the sensitivity. When a ArF eximer laser is used as the light for exposure, the resist is often applied on a substrate having a low reflection, such as an organic or inorganic anti-reflection film. When such a substrate having a low reflection is used, the profile of the resist is generally deteriorated to a taper shape, although dimension uniformity is effectively improved. Therefore, chemical amplification type resists have a problem in that performances, particularly the profile, are varied depending on the kind of the substrate.
The object of the present invention is to provide a chemical amplification type positive resist composition, which contains a resin component and an acid generator; is suitable to use in a lithography process using ArF excimer laser, KrF excimer laser or the like; is superior in various resist performances such as sensitivity, resolution, adherence to substrate and so on; has a low substrate-dependency even when it is applied to a basic substrate or a low reflection substrate; and confer a good profile on every substrate.
The co-pending application Japanese Patent Application No. 11-238542, filed by the present applicant, describes that a resin having an adamantine polymerization unit with a specific chemical structure and a of polymerization unit with a high polarity is effective in improving adherence to substrate. The present inventors have carried out further studies on systems using the resin having a butyrolactone residue disclosed in JP-A-10-274852 and JP-A-10-319595 and the resin having an adamantine polymerization unit disclosed in a Japanese Patent Application No. 11-238542 in chemical amplification type positive resist composition. As the result, they have found that, in these compositions, the resolution is improved and profiles on a basic substrate or a low reflection substrate are also improved by using an acid generator having a specific chemical structure. Thus, the present invention has been completed.
SUMMARY OF THE INVENTION
The present invention provides a positive resist composition which comprises
a resin having 2-alkyl-2-adamantyl (meth)acrylate polymerization unit represented by the following formula (I):
wherein R
1
represents hydrogen or methyl and R
2
represents an alkyl, and being insoluble or barely soluble in alkali, but being converted to soluble in alkali by the action of an acid;
and an acid generator represented by the following formula (V):
wherein Q
1
, Q
2
and Q
3
independently represent hydrogen, a hydroxyl group, an alkyl having 1 to 6 carbon atoms or an alkoxy having 1 to 6 carbon atoms, and n is an integer of 4 to 8.
DETAILED DESCRIPTION OF THE INVENTION
The polymerization unit 2-alkyl-2-adamantyl (meth)acrylate represented by the formula (I) described above is a unit formed by opening the double bond of (meth)acrylic acid portion in the 2-alkyl-2-adamantyl acrylate or 2-alkyl-2-adamantyl methacrylate. The resin as a component of the resist composition of the present invention may be a polymer having 2-alkyl-2-adamantyl (meth)acrylate polymerization unit alone, but, it is preferably a copolymer having one or more of other polymerization units together with the above unit.
Examples of the polymerization unit, other than 2-alkyl-2-adamantyl (meth)acrylate, preferably used to form a copolymer include
3-hydroxy-1-adamantyl (meth)acrylate polymerization unit represented by the following formula (II):
wherein R
3
represents hydrogen or methyl;
&agr;-(meth)acryloyloxy-&ggr;-butyrolactone polymerization unit represented by the following formula (III):
wherein R
4
represents hydrogen or methyl, and R
5
, R
6
and R
7
independently represent hydrogen or an alkyl; and
&bgr;-(meth)acryloyloxy-&ggr;-butyrolactone polymerization unit represented by the following formula (IV):
wherein R
4
, R
5
, R
6
and R
7
are as defined above.
The polymerization Unit 3-hydroxy-1-adamantyl (meth)acrylate represented by the formula (II) can be formed by opening the double bond of (meth)acrylic acid portion in 3-hydroxy-1-adamantyl (meth)acrylate. The polymerization unit &agr;-(meth)acryloyloxy-&ggr;-butyrolactone represented by the formula (III) can be formed by opening the double bond of (meth)acrylic acid portion in &agr;-(meth)acryloyloxy-&ggr;-butyrolactone which may be substituted with an alkyl in the lactone ring. The polymerization unit &bgr;-(meth)acryloyloxy-&ggr;-butyrolactone represented by the formula (IV) can be formed by opening the double bond of (meth)acrylic acid portion in &bgr;-(meth)acryloyloxy-&ggr;-butyrolactone which may be substituted with an alkyl in the lactone ring.
The resin as a component of the resist composition of the present invention has 2-alkyl-2-adamantyl (meth)acrylate polymerizatio
Inoue Hiroki
Uetani Yasunori
Ashton Rosemary
Birch & Stewart Kolasch & Birch, LLP
Sumitomo Chemical Company Limited
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