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
2000-12-01
2003-10-14
Baxter, Janet (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
C430S905000, C430S910000, C560S120000, C526S281000
Reexamination Certificate
active
06632581
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a chemical amplifying type positive resist composition used in the minute processing of a semiconductor.
In general, a lithography process using a resist composition has been adopted in the minute processing of a semiconductor. In lithography, the resolution can be improved with a decrease in wavelength of exposure light in principle as expressed by the equation of Rayleigh's diffraction limited. A g-line with a wavelength of 436 nm, an i-line with a wavelength of 365 nm, and a KrF excimer laser with a wavelength of 248 nm have been adopted as exposure light sources for lithography used in the manufacture of a semiconductor. Thus, the wavelength has become shorter year by year. An ArF excimer laser having a wavelength of 193 nm is considered to be promising as a next-generation exposure light source. As exposure light sources after next-generation, an F2 excimer laser with a wavelength of 157 nm and an extreme ultra-violet with a wavelength of 13 nm (EUV) are being considered.
A lens used in an ArF excimer laser exposure machine or an exposure machine using a light-source of shorter wave-length has a shorter lifetime as compared with lenses for conventional exposure light sources. Accordingly, the shorter time required for exposure to ArF excimer laser light is desirable. For this reason, it is necessary to enhance the sensitivity of a resist. Consequently, there has been used a so-called chemical amplifying type resist, which utilizes the catalytic action of an acid generated due to exposure, and contains a resin having a group cleavable by the acid.
It is known that, desirably, resins used in a resist for ArF excimer laser exposure have no aromatic ring in order to ensure the transmittance of the resist, but have an alicyclic ring in place of an aromatic ring in order to impart a dry etching resistance thereto.
Among these resins, a copolymer of an alicyclic unsaturated carboxylic acid ester such as norbornene carboxylate or tetracyclododecene carboxylate and maleic anhydride is by far superior to a resin comprising an alicyclic (meth)acrylate in terms of raw material cost.
Among such alicylic unsaturated carboxylic acid ester resins, those having a tert-butyl group as an acid unstable group which is cleavable due to an action of acid and hence has a function of changing the solubility of the resin, for example, a resin having a unit of tert-butyl 5-norbornene-2-carboxylate represented by the formula below, have been reported and studied. However, resists using these resins have not necessarily exhibited satisfactory resist performance.
An object of the present invention is to improve various resist performance such as sensitivity and resolution by using a resin having a unit derived from a specified alicyclic unsaturated carboxylic acid ester in a chemically amplified positive resist composition comprising a resin component and an acid-generating agent which is suitable for excimer laser lithography utilizing ArF, KrF or the like. The inventors of the present invention have found the fact that use of a resin containing a copolymer of an alicyclic unsaturated carboxylic acid ester having a specified protective group and maleic anhydride in a resist enables the resist to exhibit an improved resolution. Thus, the present invention has been attained.
SUMMARY OF THE INVENTION
The present invention provides a chemically amplified positive resist composition which comprises a resin (X) which, per se, is insoluble or slightly soluble in alkali but becomes soluble in alkali by the action of acid, and has a polymeric unit (a) derived from an alicyclic unsaturated carboxylic acid ester in which a carboxylic acid ester group represented by the formula (I):
wherein R
1
represents an alkyl having 1 to 4 carbon atoms, R represents an alicyclic hydrocarbon residue which may be optionally substituted with a group selected from hydroxyl and oxo, and R
2
represents an alkyl having 1 to 4 carbon atoms, or R and R
2
, together with carbon atoms to which R
2
and R are bonded, form a ring, is bonded to an alicyclic hydrocarbon having a polymerizable: carbon-carbon double bond in its ring; and a polymeric unit (b) derived from maleic anhydride; and an acid-generating agent (Y).
EMBODIMENTS OF THE INVENTION
In the present invention, the resin (X), as a component of the resist composition, is a copolymer of polymeric unit (a) derived from an alicyclic unsaturated carboxylic acid ester in which a carboxylic acid ester group of the above formula (I) is bonded to an alicyclic unsaturated hydrocarbon and polymeric unit (b) derived from maleic anhydride. The resist composition of the present invention is largely characterized by the presence of a bulky protective group such that R is an alicyclic hydrocarbon residue optionally having a substituent, or R and R
2
, together with carbon atoms to which they are bonded, form a ring. By virtue of this characteristic, the resist composition exhibits improved sensitivity and resolution and is capable of providing a high contrast pattern.
The polymeric unit (a) has a carboxylic acid ester moiety represented in the formula (I), and is formed by opening an unsaturated bond (double bond) in the alicyclic unsaturated ring. The polymeric unit (a) can be represented by the following formula (II):
where R
1
, R and R
2
are as defined above, and a ring A represents an alicyclic hydrocarbon ring.
The polymeric unit (b) derived from maleic anhydride is formed by opening a double bond in maleic anhydride and can be represented by the following formula (III):
The resin (X) used in the present invention can be obtained by copolymerization of an alicyclic unsaturated carboxylic acid ester represented by the following formula (IV):
where R
1
, R and R
2
are as defined above, and a ring B represents an alicyclic hydrocarbon which becomes the ring A in the formula (II) when its double bond has been opened by polymerization, and maleic anhydride.
In the formulae (I), (II) and (IV), the alkyl group represented by R
1
or R
2
has 1 to 4 carbon atoms, and examples of such alkyl groups include methyl, ethyl, propyl, isopropyl and butyl. The alicyclic hydrocarbon residue represented by R may be combined with hydroxyl or oxo (═O). Examples of the alicyclic hydrocarbon residue represented by R include monocyclic ones such as cycloalkyl and alkylcycloalkyl in which an alkyl having 1 to 4 carbon atoms is bonded to cycloalkyl, and polycyclic ones such as norbornyl and adamantyl. The alicyclic hydrocarbon residue represented by R usually can have about 5 to about 12 carbon atoms, and specific examples of the alicyclic hydrocarbon residues include cyclohexyl, alkylcyclohexyl, hydroxycyclohexyl, oxocyclohexyl, norbornyl, and adamantyl. The ring formed by R and R
2
together with carbon atoms to which they are bonded is also an alicyclic hydrocarbon ring, and examples of such rings include monocyclic ones such as cycloalkyl and alkylcycloalkyl, and polycyclic ones such as norbornyl and adamantyl. The ring formed by R and R
2
together with carbon atoms to which they are bonded, also, can have about 5 to about 12 carbon atoms.
The ring A in the formula (II) may be either a monocylic one such as cyclohexane ring or a polycyclic one such as norbornane ring, tricyclodecane ring or tetracyclododecane ring. Particularly, polycyclic ones having two or more rings are preferable. Preferably, the polycyclic ring has 7 to 12 carbon atoms. Accordingly, preferable ones of the unit represented by the formula (II) can generally be represented by the following formula (IIa):
where R
1
, R and R
2
are as defined above, and a bivalent group D depicted by dotted line is either absent or a bivalent saturated hydrocarbon residue. More specifically, in the case where the ring A in the formula (II) is a norbornane ring, the unit can be represented by the formula (IIb) below. In the case where the ring A is a tricyclodecane ring, for example, tricyclo[5.2.1.0
2,6
]decane, the unit can be represented by the formula (IIc) belo
Kim Seong-Hyeon
Uetani Yasunori
Baxter Janet
Birch & Stewart Kolasch & Birch, LLP
Sumitomo Chemical Company Limited
Thornton Yvette C.
LandOfFree
Chemically amplified positive resist composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Chemically amplified positive resist composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chemically amplified positive resist composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3135136