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
2000-10-27
2004-01-06
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
C430S325000, C430S326000
Reexamination Certificate
active
06673511
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel, chemically amplified resist composition suited for use in micro-lithography.
2. Description of the Related Art
The miniaturization of a pattern rule has been demanded in order to cope with a recent tendency of LSI technology to higher integration and higher speed. Under such a circumstance, far ultraviolet lithography has been regarded promising as the next-generation of micro-lithography. Even a pattern of 0.3 &mgr;m or less can be formed by far ultraviolet lithography, and use of a resist material exhibiting low light absorption makes it possible to form a pattern with side-wall angles nearly vertical to a substrate. In recent years, a technique making use of a high intensity KrF excimer laser as a far-UV light source has drawn attentions. There is accordingly a demand for the development of a low light absorbing and highly sensitive resist material which permits the use of the above-described technique for mass production.
From such a viewpoint, the recently-developed, chemically amplified positive type resist materials as described in Japanese Patent Publication (JP-B) No. 2-27660/'90 and Japanese Patent Provisional Publication (JP-A) No. 63-27829/'88 using an acid catalyst are particularly promising resist materials suited for far-UV lithography, because of their excellent characteristics such as high sensitivity, resolution and dry etching resistance.
Prior-art chemically amplified resists are however accompanied with the problems such as PED (Post Exposure Delay) that line patterns have a T-top profile, in other words, patterns become thick at the top, when the dwelling time from exposure to PEB (post exposure bake) is extended; and a so-called “trailing phenomenon” that patterns in the vicinity of a basic substrate, particularly, a substrate made of silicon nitride or titanium nitride are widened.
It is presumed that the T-top profile results from lowering in the solubility of the surface of a resist film, while the trailing phenomenon on a substrate results from lowering in solubility in the vicinity of the substrate.
In addition, during the time from exposure to PEB, a dark reaction for eliminating an acid-labile group proceeds, leading to a problem that the leaving size of the line of a positive resist decreases.
These problems are serious hindrance to practical use of the chemically amplified resist. Such problems of the conventional chemically amplified positive resist material not only make difficult dimensional control upon lithography but also impair dimensional control upon processing of a substrate by using dry etching [refer to: W. Hinsberg, et al., J. Photopolym. Sci. Technol., 6(4), 535-546(1993) and T. Kumada, et al., J. Photopolym. Sci. Technol., 6(4), 571-574(1993)].
It is understood that in these chemically amplified positive type resist materials, a basic compound in the air or on the surface of a substrate largely takes part in the problem of PED or trailing phenomenon on the substrate. An acid on the surface of a resist film generated by exposure to light reacts with a basic compound in the air and is thereby deactivated. The longer the dwelling time from exposure to PEB becomes, the more the amount of a deactivated acid increases, making it difficult to cause decomposition of an acid-labile group. An insolubilized layer is therefore formed on the surface and a pattern inevitably has a T-top configuration.
It is well known that addition of a basic compound is effective for overcoming PED, because it can suppress the influence of a basic compound in the air (as described in Japanese Patent Provisional Publication Nos. 5-232706/'93, 5-249683/'93, 5-158239/'93, 5-249662/'93, 5-257282/'93, 5-289322/'93, 5-289340/'93, 6-194834/'93, 6-242605/'94, 6-242606/'94, 6-263716/'94, 6-263717/'94, 6-266100/'94, 6-266111/'94, 7-128859/'95, 7-92678/'95, 7-92680/'95, 7-92681/'95, 7-120929/'95 and 7-134419/'95).
As the basic compound, a nitrogen-containing compound is well known and examples include amine compounds and amide compounds having a boiling point of 150° C. or greater. Specific examples include pyridine, polyvinyl pyridine, aniline, N-methylaniline, N,N-dimethylaniline, o-toluidine, m-toluidine, p-toluidine, 2,4-lutidine, quinoline, isoquinoline, formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, 2-pyrrolidone, N-methylpyrrolidone, imidazole, &agr;-picoline, &bgr;-picoline, &ggr;-picoline, o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 2-quinolinecarboxylic acid, 2-amino-4-nitrophenol, and triazine compounds such as 2-(p-chlorophenyl)-4,6-trichloromethyl-s-triazine. Among them, pyrrolidone, N-methylpyrrolidone, o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid and 1,2-phenylenediamine are typical examples.
SUMMARY OF THE INVENTION
Although the above-described nitrogen-containing compounds can ease the T-top problem at an acid dissociation constant pKa ranging from 2 to 6, they cannot control reaction, that is, acid diffusion upon use of a highly-reactive acid-labile group.
When a weak base is added, a dark reaction in PED proceeds at an unexposed portion, thereby causing a reduction in a line size (slimming) and a decrease in film thickness on the line surface. Addition of a strong base having a pKa of 7 or greater is effective for overcoming the above-described problem.
However, higher pKa does not always bring about good results. Even when a superstrong base such as DBU (1,8-diazabicyclo[5,4,0]-7-undecene) or DBN (1,5-diazabicyclo[4,3,0]-5-nonen), proton sponge or a quaternary amine such as tetramethylammonium hydroxide is added, a sufficient effect is not available.
The present inventors have carried out various investigations. As a result, it has been found that amines represented by formulas (I) to (III) and (1) to (4) having a carbonyl group, an ester group, or a carbonate group are highly effective for preventing a decrease in the thickness of a resist film and also for enlarging a focus margin and bringing about dimensional stability.
N
(X)
n
(Y)
3−n
(I)
wherein, n stands for 1, 2 or 3, preferably 1 or 2, side chains Xs may be the same or different and each independently represents —R
1
—O—R
2
or —R
1
—C(═O)—O—R
61
(in which R
1
s are the same or different and each independently represents an alkylene group of 1 to 5 carbon atoms, R
2
s are the same or different and each independently represents a linear, branched or cyclic alkyl group of 1 to 20 carbon atoms containing a carbonyl or ester group, and R
61
s are the same or different and each independently represents a linear, branched or cyclic alkyl group of 1 to 20 carbon atoms which may contain a carbonyl group, an ester group, an ether group, a hydroxyl group or a lactone ring, or R
1
and R
2
, or R
1
and R
61
in the same side chain may be coupled together to form a ring); and side chains Ys are the same or different and each independently represents a hydrogen atom or a linear, branched or cyclic alkyl group of 1 to 20 carbon atoms which may contain an ether or hydroxyl group.
In the above-described formulas, R
1
s are the same or different and each independently represents an alkylene group of 1 to 5 carbon atoms, R
2
s are the same or different and each independently represents a linear, branched or cyclic alkyl group of 1 to 20 carbon atoms containing a carbonyl or ester group, R
3
represents a hydrogen atom or a linear, branched or cyclic alkyl group of 1 to 20 carbon atoms, and R
4
s are the same or different and each independently represents a linear, branched or cyclic alkyl group of 1 to 20 carbon atoms which may contain a carbonyl, ester or ether group.
wherein, R
62
represents a linear or branched alkylene group of 1 to 5 carbon atoms, p stands for 0, 1 or 2 with the proviso
Hatakeyama Jun
Ohsawa Youichi
Watanabe Takeru
Ashton Rosemary
Myers Bigel & Sibley Sajovec, PA
Shin-Etsu Chemical Co. , Ltd.
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