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
2001-03-05
2003-01-21
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
C430S326000, C430S322000, C430S320000, C430S286100, C560S126000
Reexamination Certificate
active
06509135
ABSTRACT:
This invention relates to (1) a polymer comprising specific units with a robust alicyclic structure having both polar groups and acid labile groups, (2) a resist composition comprising the polymer as a base resin, having improved reactivity, substrate adhesion and etching resistance, and especially suited as micropatterning material for VLSI fabrication, and (3) a patterning process using the resist composition.
BACKGROUND OF THE INVENTION
While a number of recent efforts are being made to achieve a finer pattern rule in the drive for higher integration and operating speeds in LSI devices, deep-ultraviolet lithography is thought to hold particular promise as the next generation in microfabrication technology. In particular, photolithography using a KrF or ArF excimer laser as the light source is strongly desired to reach the practical level as the micropatterning technique capable of achieving a feature size of 0.3 &mgr;m or less.
The resist materials for use in photolithography using light of an excimer laser, especially ArF excimer laser having a wavelength of 193 nm, are, of course, required to have a high transmittance to light of that wavelength. In addition, they are required to have an etching resistance sufficient to allow for film thickness reduction, a high sensitivity sufficient to eliminate any extra burden on the expensive optical material, and especially, a high resolution sufficient to form a precise micropattern. To meet these requirements, it is crucial to develop a base resin having a high transparency, rigidity and reactivity. None of the currently available polymers satisfy all of these requirements. Practically acceptable resist materials are not yet available.
Known high transparency resins include copolymers of acrylic or methacrylic acid derivatives and polymers containing in the backbone an alicyclic compound derived from a norbornene derivative. All these resins are unsatisfactory. For example, copolymers of acrylic or methacrylic acid derivatives are relatively easy to increase reactivity in that highly reactive monomers can be introduced and acid labile units can be increased as desired, but difficult to increase rigidity because of their backbone structure. On the other hand, the polymers containing an alicyclic compound in the backbone have rigidity within the acceptable range, but are less reactive with acid than poly(meth)acrylate because of their backbone structure, and difficult to increase reactivity because of the low freedom of polymerization. Therefore, some resist compositions which are formulated using these polymers as the base resin, fail to withstand etching although they have satisfactory sensitivity and resolution. Some other resist compositions are highly resistant to etching, but have low sensitivity and low resolution below the practically acceptable level.
SUMMARY OF THE INVENTION
An object of the invention is to provide (1) a polymer having improved reactivity, rigidity and substrate adhesion, (2) a resist composition comprising the polymer as a base resin and achieving significantly surpassing sensitivity, resolution and etching resistance over prior art compositions, and (3) a patterning process using the resist composition.
It has been found that a polymer comprising recurring units of the following general formula (1) and having a weight average molecular weight of 1,000 to 500,000 possesses improved reactivity, rigidity and substrate adhesion, and that a resist composition using the polymer as a base resin has a high sensitivity, high resolution and high etching resistance and is very useful in precise microfabrication.
In one aspect, the invention provides a polymer comprising recurring units of the following general formula (1) and having a weight average molecular weight of 1,000 to 500,000.
Herein R
1
is hydrogen, methyl or CH
2
CO
2
R
3
; R
2
is hydrogen, methyl or CO
2
R
3
; R
3
is a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms; R
4
is hydrogen, a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms, a straight, branched or cyclic alkoxyalkyl group of 2 to 15 carbon atoms, or a straight, branched or cyclic acyl group of 1 to 15 carbon atoms; R
5
and R
15
each are an acid labile group; at least one of R
6
to R
9
is a carboxyl or hydroxyl-containing monovalent hydrocarbon group of 1 to 15 carbon atoms, and the remainders are independently hydrogen or a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms, or R
6
to R
9
, taken together, may form a ring, and when they form a ring, at least one of R
6
to R
9
is a carboxyl or hydroxyl-containing divalent hydrocarbon group of 1 to 15 carbon atoms, and the remainders are independently a single bond or a straight, branched or cyclic alkylene group of 1 to 15 carbon atoms; at least one of R
10
to R
13
is a monovalent hydrocarbon group of 2 to 15 carbon atoms containing a —CO
2
— partial structure, and the remainders are independently hydrogen or a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms, or R
10
to R
13
, taken together, may form a ring, and when they form a ring, at least one of R
10
to R
13
is a divalent hydrocarbon group of 1 to 15 carbon atoms containing a —CO
2
— partial structure, and the remainders are independently a single bond or a straight, branched or cyclic alkylene group of 1 to 15 carbon atoms; R
14
is a polycyclic hydrocarbon group of 7 to 15 carbon atoms or an alkyl group containing such a polycyclic hydrocarbon group; Z is a trivalent hydrocarbon group of 1 to 10 carbon atoms, or Z forms a ring with R
1
, and in this event, R
1
is methylene and Z is a tetravalent hydrocarbon group of 1 to 10 carbon atoms; X is —CH
2
— or —O—; k is equal to 0 or 1, x is a number of more than 0, a, b, c and d are 0 or positive numbers, satisfying x+a+b+c+d=1.
Preferably, the acid labile groups represented by R
5
and R
15
in formula (1) are selected from the class consisting of groups of the following general formulae (L1) to (L4), tertiary alkyl groups of 4 to 20 carbon atoms, trialkylsilyl groups in which each alkyl moiety has 1 to 6 carbon atoms, oxoalkyl groups of 4 to 20 carbon atoms, and mixtures of any of the foregoing.
Herein R
L01
and R
L02
each are hydrogen or a straight, branched or cyclic alkyl group of 1 to 18 carbon atoms; R
L03
is a monovalent hydrocarbon group of 1 to 18 carbon atoms which may contain a hetero atom such as oxygen atom; a pair of R
L01
and R
L02
, R
L01
and R
L03
, or R
L02
and R
L03
may form a ring, each of R
L01
, R
L02
and R
L03
is a straight or branched alkylene group of 1 to 18 carbon atoms when they form a ring; R
L04
is a tertiary alkyl group of 4 to 20 carbon atoms, a trialkylsilyl group in which each alkyl moiety has 1 to 6 carbon atoms, an oxoalkyl group of 4 to 20 carbon atoms, or a group of formula (L1); R
L05
is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms or a substituted or unsubstituted aryl group of 6 to 20 carbon atoms; R
L06
is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms or a substituted or unsubstituted aryl group of 6 to 20 carbon atoms; R
L07
to R
L16
are independently hydrogen or monovalent hydrocarbon groups of 1 to 15 carbon atoms which may contain a hetero atom, R
L07
to R
L16
, taken together, may form a ring, and each of R
L07
to R
L16
represents a divalent hydrocarbon group of 1 to 15 carbon atoms which may contain a hetero atom, when they form a ring, or two of R
L07
to R
L16
which are attached to adjoining carbon atoms may bond together directly to form a double bond; y is an integer of 0 to 6, m is equal to 0 or 1, and n is equal to 0, 1, 2 or 3, satisfying 2m+n=2 or 3.
A resist composition comprising the polymer defined above is also provided.
In a further aspect, the invention provides a process for forming a resist pattern comprising the steps of applying the resist composition defined above onto a substrate to form a coating; heat treating the coating and then exposing it to high-energy radiation or electron beams through
Hasegawa Koji
Hatakeyama Jun
Kinsho Takeshi
Nishi Tsunehiro
Watanabe Takeru
Baxter Janet
Clarke Yvette M.
Millen White Zelano & Branigan P.C.
Shin-Etsu Chemical Co. , Ltd.
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