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
2001-12-21
2004-04-27
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
C430S296000, C430S914000, C430S942000, C430S966000
Reexamination Certificate
active
06727040
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a positive resist composition to be irradiated with one of an electron beam and X-ray, in particular, relates to a chemical amplification system positive resist composition to be irradiated with one of an electron beam and X-ray, which is excellent in a pattern profile obtained by irradiation with electron beams or X-rays, and is high sensitivity.
BACKGROUND OF THE INVENTION
The degree of integration of integrated circuits has been heightened more and more, and processing of ultra-fine pattern comprising a line width of half a micrometer or less has been required in the manufacture of semiconductor substrates, such as ultra LSI. For satisfying the necessity, the wavelengths used in an exposure apparatus for photo-lithography have become short more and more, and the use of far ultraviolet rays and excimer laser rays (XeCl, KrF and ArF) has been discussed now. Still further ultra-fine pattern formation by electron beams or X-rays has been discussed.
In particular, electron beams or X-rays are positioned as the pattern forming technique of the next generation or the next of the next generation, and the development of positive and negative resist compositions capable of obtaining high sensitivity, high resolution power and a rectangular profile has been desired.
Further, positive resists for electron beams or X-rays are easily influenced by basic contaminants in the air, or liable to be influenced by being exposed to air in and out of an irradiation apparatus (drying of the film), and the surface of the resists becomes hardly soluble. As a result, there arises a problem that the resists become a T-top shape (the surface forms T-shaped eaves) in case of a line pattern, and the surface becomes a capping shape (eaves are formed on the contact hole surface) in case of a contact hole pattern.
On the other hand, there arises a problem of film decrease when the binder is made hydrophilic for the purpose of preventing the capping shape or the T-top shape.
As the mechanism of acid generation from an onium salt series acid generating agent by electron beams or X-rays in a chemical amplification resist, the mechanism that a secondary electron is emitted after almost all the radiation energy is absorbed by the matrix polymer, and the onium salt is reduced by the secondary electron, thereby an acid is generated is described in
Journal of Photopolymer Science and Technology
, Vol. 11, No. 4, pp. 577 to 580 (1998).
The entire process of electron beam or X-ray exposure is generally performed in a high vacuum, but when the resist is allowed to stand in a high vacuum after exposure, the stability of the resist performance is sometimes malignantly influenced.
From the above point of view, a resist excellent in sensitivity, resolution and PED (post exposure delay) stability in a vacuum has been desired. PED stability is the stability of a coated film in case of allowing the film to stand in and out of the irradiation apparatus during the time until heating treatment is performed after irradiation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a positive resist composition for electron beams or X-rays which is high sensitivity, high resolution and excellent in PED stability.
As a result of eager investigations aiming at high performances of resist compositions, the present inventors have found that a resist which is high sensitivity, high resolution and excellent in stability in a vacuum can be obtained by using a polymer having a group containing a structure having an ionization potential value (Ip) smaller than the Ip of a p-hydroxystyrene unit (p-ethylphenol) (Ip: about 8.9 eV). That is, the above object of the present invention has been achieved by the following positive resist composition for electron beams or X-rays of the present invention.
(1) A positive resist composition to be irradiated with one of an electron beam and X-ray, which comprises:
(a) a compound capable of generating an acid upon irradiation with one of electron beam and X-ray;
(b1) a resin: increasing the solubility in an alkali developer by the action of an acid; and having a group capable of leaving by the action of an acid, in which the leaving group includes a residue of a compound, the compound having a smaller ionization potential value than p-ethylphenol; and
(c) a solvent.
(2) A positive resist composition to be irradiated with one of an electron beam and X-ray, which comprises:
(a) a compound capable of generating an acid upon irradiation with one of electron beam and X-ray;
(b2) a resin: increasing the solubility in an alkali developer by the action of an acid; and having a repeating unit represented by formula (I):
wherein R
1
represents a hydrogen atom or a methyl group; R
2
and R
3
each independently represents a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms; W represents a divalent organic group; X represents an organic group which satisfies that the ionization potential value of a compound represented by H—O—X is smaller than that of p-ethylphenol; and n represents an integer of from 1 to 4, and when n represents from 2 to 4, a plurality of W's are the same or different; and
(c) a solvent.
(3) The positive resist composition as described in item (2), wherein X in formula (I) is represented by formula (II):
—L—Y (II)
wherein L represents a single bond or an alkylene group; and Y represents a group selected from the following formulae:
wherein R
4
represents a straight chain or branched alkyl group having from 1 to 6 carbon atoms; n1 represents an integer of from 0 to 3; n2 represents an integer of from 0 to 7; n3 represents an integer of from 0 to 9; n4 represents an integer of from 0 to 9; and n5 represents an integer of from 0 to 9.
(4) The positive resist composition as described in item (1), wherein the compound (a) contains at least one compound represented by formula (I′), (II′) or (III′):
wherein R
1
to R
37
, which are the same or different, each represents a hydrogen atom, a straight chain, branched or cyclic alkyl group, a straight chain, branched or cyclic alkoxyl group, a hydroxyl group, a halogen atom, or an —S—R
38
group; R
38
represents a straight chain, branched or cyclic alkyl group, or an aryl group; at least two of R
1
to R
15
, at least two of R
16
to R
27
, and at least two of R
28
to R
37
may be bonded to form a ring containing at least one selected from a single bond, carbon, oxygen, sulfur and nitrogen; and X
−
represents an anion of a sulfonic acid.
(5) The positive resist composition as described in item (4), wherein X
−
represents an anion of a benzenesulfonic acid, an anion of a naphthalenesulfonic acid or an anion of an anthracenesulfonic acid, each of which contains at least one member selected from the group consisting of:
at least one fluorine atom;
a straight chain, branched or cyclic alkyl group substituted with at least one fluorine atom;
a straight chain, branched or cyclic alkoxyl group substituted with at least one fluorine atom;
an acyl group substituted with at least one fluorine atom;
an acyloxy group substituted with at least one fluorine atom;
a sulfonyl group substituted with at least one fluorine atom;
a sulfonyloxy group substituted with at least one fluorine atom;
a sulfonylamino group substituted with at least one fluorine atom;
an aryl group substituted with at least one fluorine atom;
an aralkyl group substituted with at least one fluorine atom; and
an alkoxycarbonyl group substituted with at least one fluorine atom.
(6) The positive resist composition as described in item (1), wherein the solvent (c) contains propylene glycol monomethyl ether acetate.
(7) The positive resist composition as described in item (1), which further comprises (e) an organic basic compound.
(8) The positive resist composition as described in item (1), which further comprises (f) a surfactant containing at least one of a fluorine atom and a silicon atom.
(9) The positive resist composition as described in item (2), wherein th
Mizutani Kazuyoshi
Sasaki Tomoya
Shirakawa Koji
Ashton Rosemary
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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