Radiation sensitive compositions containing image quality...

Details Radiation sensitive compositions containing image quality... Radiation sensitive compositions containing image quality...

2000-07-20

2003-02-04

Huff, Mark F. (Department: 1756)

Radiation imagery chemistry: process, composition, or product th

Imaging affecting physical property of radiation sensitive...

Radiation sensitive composition or product or process of making

C430S283100, C430S322000, C430S920000

Reexamination Certificate

active

06514664

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to radiation sensitive compositions. More particularly, the present invention relates to chemically amplified resist compositions containing image quality and profile enhancement additives.
2. Description of Related Art
The complexity of integrated circuit (IC) devices and computer chips has increased dramatically as greater demands are placed on the semiconductor industry. Integrated circuits and computer chips are now manufactured with smaller critical dimensions, requiring the photolithographic image patterns formed on wafers be less than 0.3 micron (&mgr;m) in resolution. To achieve this objective, photoresists used for photolithographic imaging are required to have better resolution, improved sensitivity, and more vertical profile than the state-of-the-art photoresists of a decade ago.
To obtain higher resolution patterns, chemically amplified photoresists are generally used. These chemically amplified photoresists utilize a combination of a selected polymer resin such as a partially modified or protected poly(hydroxystyrene) resin or copolymer of a partially modified hydroxystyrene with other monomers such as acrylates or methacrylates, a photoacid generating compound (PAG), and a selected solvent.
Semiconductor manufacturers, however, are always seeking ways to improve the resolution and profile image acuity of these photoresist compositions. Thus, the present invention provides a means to further improve the resolution of resist patterns and provide resist patterns with vertical side walls profiles and flat tops.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a radiation sensitive composition comprising a polymer resin, a photoacid generator, a solvent, and a heterocyclic carbon and nitrogen containing additive selected from the group consisting of:
1-phenyl-2-pyrrolidinone and compounds of the formulas (I), (II), (III), and (IV):
where R
1
is —H, —NH
2
—, —OH, —N(CH
3
)
2
, —NH—CO—CH
3
, or
where R
2
is —CH
3
or benzoyl;
where R
3
is —H, or C
1
-C
4
alkyl;
W, X, Y, and Z are each independently selected from —CH
2
—,
 —CH(CH
3
)—, —C(CH
3
)
2
—, —NH—, or —N(CH
3
)—, with the proviso that at least one of W, X, Y, or Z is
 and at least one of W, X, Y, or Z is —NH— or —N(CH
3
)—;
where A is —CH═ or
R
4
is —H, —CH
3
, or —CH
2
—CH(CH
3
)
2
;
R
5
is —H, —CH
3
, or —CH
2
—CH(OH)—CH
2
(OH);
R
6
is —H;
B and D are identical and selected from
one p and q is 0 and the other p and q is 1, when A is —CH═; and
p and q are both 1, when A is
and mixtures thereof.
Optionally, the radiation sensitive composition may include one or more basic compounds in addition to the aforedescribed additives.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have discovered that inclusion of the specific heterocyclic additives in a radiation sensitive composition, i.e. a chemically amplified photoresist composition, will provide significantly improved resist patterns with crisper vertical side wall profiles, square corners, and flat tops.
The radiation sensitive composition contains a polymer resin, a photoacid generator, a solvent, and a heterocyclic additive.
Additives that are suitable for use in the present invention are, for example, compounds that have the formula shown in formulae (I), (II), and (III):
where R
1
is —H, —NH
2
—, —OH, —N(CH
3
)
2
, —NH—CO—CH
3
, or
where R
2
is —CH
3
or benzoyl;
where R
3
is —H, or C
1
-C
4
alkyl;
where W, X, Y, and Z are each independently selected from —CH
2
—,
 —CH(CH
3
)—, —C(CH
3
)
2
—, —NH—, or —N(CH
3
)—, with the proviso that at least one of W, X, Y, or Z is
 and at least one of W, X, Y, or Z is —NH— or —N(CH
3
)—.
Additives of the present invention also include, for example, compounds conforming to formula (IV):
where A is —CH═ or
R
4
is —H, —CH
3
, or —CH
2
—CH(CH
3
)
2
;
R
5
is —H, —CH
3
, or —CH
2
—CH(OH)—CH
2
(OH);
R
6
is —H;
B and D are identical and selected from
one p and q is 0 and the other p and q is 1,when A is —CH═; and
p and q are both 1, when A is
Preferably, the additive compound is 1-phenyl-2-pyrolidinone or a compound of formulas (I), (II) and (III), selected from the group consisting of:
Preferably, the additive compound of formula (IV) is selected from the group consisting of:
In the absence of a basic compound, the additive is included at about 0.01 to 20 parts by weight per 100 parts by weight of the photoacid generator used in the radiation sensitive composition. Preferably the additive is about 5 to 10 parts by weight, more preferably about 6 to 8 parts by weight per 100 parts by weight of the photoacid generator in the radiation sensitive composition, when the basic compound is not included.
Another essential component of the present composition is a polymer. The polymer may be a polymer or copolymer having one or more acid labile groups, capable of being released from the polymer in the presence of an acid to increase the solubility of the polymer in an alkaline developing solution can be used in the radiation sensitive composition of the present invention.
Polymers that are suitable are, for example, poly-1-cyclohexyl ethoxy/ethoxy styrene-co-hydroxy styrene, poly-1-cyclohexyl ethoxy/ethoxy styrene-co-hydroxy styrene-co-acetoxy styrene terpolymer, and poly-1-cyclohexyl ethoxy/ethoxy styrene-co-hydroxy styrene-co-t-butyl styrene terpolymer. The preferred polymer is poly-1-cyclohexyl ethoxy/ethoxy styrene-co-hydroxy styrene.
Additional polymers that may be used include, for example, polyhydroxystyrene and derivatives thereof. Preferred are those copolymers of polyhydroxystyrene and polyhydroxystyrene derivatives wherein hydrogen atoms of some OH groups of polyhydroxystyrene are replaced by any suitable acid labile groups. The acid labile group can be, for example, tert-butyl, tert-butoxycarbonyl, tert-butoxycarbonyl oxymethyl, and tetrahydropyranyl, methoxymethyl, trimethylsilyl, acetal groups, and tert-butyldimethylsilyl groups. The hydroxystyrene copolymers can be, for example, copolymers of hydroxystyrene and styrene, copolymers of hydroxystyrene and tert-butyl acrylate, copolymers of hydroxystyrene and tert-butyl methacrylate, copolymers of hydroxystyrene and tert-butyl vinyl benzoate, copolymers of hydroxystyrene and maleic anhydride, and copolymers of hydroxystyrene and di-tert-butyl maleate. The polyhydroxystyrene and derivatives thereof should preferably have a weight average molecular weight of about 5,000 to about 100,000.
Moreover, the polymer may be a copolymer containing an alicyclic moiety in a monomer. The alicyclic monomer can be substituted or unsubstituted. Such polymers are described in U.S. Pat. No. 5,843,624 and EP-0930541A1, which are incorporated herein by reference. For example, polymers such as norbornene, 1,5 cyclooctadiene, 1,5-dimethyl-1,5-cyclooctadiene, 5,6-dihydrodicyclopentadiene, and the like, may be used.
The present radiation sensitive composition includes a photoacid generator (PAG). The function of the PAG is to produce an acid upon exposure to radiation/photolysis, thereby increasing alkali solubility of the polymer resin by releasing acid-labile groups from the polymer.
Any suitable photoacid generator compound may be used in the photoresist composition. The photoacid generator compound may be, for example, onium salts such as diazonium, sulfonium, sulfoxonium and iodonium salts, sulfone compounds, sulfonate compounds, sulfonyloxyimide compounds, diazomethane compounds, and disulfone compounds. In addition, suitable photoacid generator compounds are disclosed in U.S. Pat. Nos. 5,558,978 and 5,468,589, which are incorporated herein by reference.
Sulfonium salts such as triphenylsulfonium perfluoro octane sulfonate and triphenylsulfonium perfluoro butane sulfonate are further examples of suitable photoacid generators. A comprehensive listing and description of sulfonium and iodonium photoacid generators that can be included in the present composition is found in U.S. Pat. No. 6,010,820, which is incorporated h

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