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
2001-08-28
2004-08-17
Walke, Amanda (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
C430S311000, C430S315000
Reexamination Certificate
active
06777158
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for the preparation of a semiconductor device or, more particularly, to a high-yield method for the preparation of a semiconductor device of high reliability by decreasing the number of defects occurring in the process of photolithographic patterning of a photoresist layer.
As a trend in recent years, the requirement for a higher degree of integration in semiconductor devices is increasing year by year and mass production of LSIs having a fineness of the design rule of about 0.20 &mgr;m has now left the starting point and the schedule for the mass production of LSIs having fineness of the design rule of about 0.15 &mgr;m is rapidly approaching its starting point.
In connection with this trend toward greatly increased fineness of patterning in the manufacture of semiconductor devices, upgrading of the photoresist compositions, which are pattern-wise exposed to KrF excimer laser beams, is now required to comply with the 0.12 to 0.18 &mgr;m fineness of patterning for line-and-space patterns, hole patterns and isolated patterns.
Along with the above mentioned trend toward increased fineness of patterning of photoresist layers, on the other hand, another important problem to be solved is the number of defects occurring in the patterned resist layer after development, which was not taken as so serious heretofore. Namely, high-yield mass production of semiconductor devices having high electric reliability can be accomplished only by greatly decreasing the number of defects occurring in the photoresist layer.
The defects here implied include any of the defects found in the patterned resist layer such as adherence of scums, disordered patterning of the resist layer and others, which can be detected by inspecting the patterned resist layer after development just from above on a surface-defect inspection instrument such as the instrument Model KLA manufactured by KLA Tencole Co.
SUMMARY OF THE INVENTION
Under the above described circumstances, the present invention has an object to provide a method for the production of semiconductor devices of high electrical reliability in a high yield by greatly suppressing occurrence of defects in the patterned resist layer which was not taken as so serious heretofore from the standpoint of quality control.
Thus, the present invention provides an improvement in a method for the preparation of a semiconductor device by forming a patterned resist layer on the surface of a substrate by pattern-wise light-exposure of a photoresist layer of a chemical-amplification positive-working photoresist composition comprising (A) a compound capable of generating an acid by irradiation with actinic rays and (B) a resinous compound capable of being imparted with increased solubility in an aqueous alkaline solution in the presence of an acid, which improvement comprises decreasing the number of defects in the patterned resist layer by selecting the photoresist composition of which the photoresist layer before the pattern-wise light-exposure exhibits reduction of thickness at 23° C. in an aqueous alkaline solution at a rate in the range from 0.09 to 1.0 nm/second.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As is understood from the above given description, the unexpected discovery leading to the most characteristic feature of the invention is that the number of defects in the patterned photoresist layer obtained by development after pattern-wise light-exposure of a photoresist layer in the photolithographic process for the manufacture of semiconductor devices can be greatly decreased when the photoresist layer before the pattern-wise light-exposure exhibits reduction of the thickness in an aqueous alkaline solution at a specified rate.
The photoresist composition to which the present invention is applicable is a chemical-amplification positive-working photoresist composition comprising, as the essential ingredients, the above described components (A) and (B). It is essential in the present invention that the types and compounding proportion of these ingredients should be so selected that the photoresist layer of the composition before light-exposure exhibits a rate of film thickness reduction specified above in an aqueous alkaline solution which is a 2.38% by weight aqueous solution of tetramethylammonium hydroxide.
The component (A) comprised in the photoresist composition used in the present invention is a compound capable of generating an acid when irradiated with actinic rays. The component (A) is not particularly limitative and can be selected from those radiation-sensitive acid-generating compounds formulated in conventional chemical-amplification photoresist compositions. Examples of suitable radiation-sensitive acid-generating compounds include diazomethane compounds, nitrobenzyl compounds, sulfonic acid esters, onium salt compounds, benzoin tosylate compounds, halogen-containing triazine compounds, cyano group-containing oximesulfonate compounds and the like, of which diazomethane compounds and onium salt compounds having a C
1
-C
15
halogenoalkyl sulfonic acid as the anionic moiety are preferable.
Examples of the diazomethane compounds include bis(p-toluenesulfonyl)diazomethane, bis(1,1-dimethylethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane and bis(2,4-dimethylphenylsulfonyl)diazomethane.
Examples of the above specified onium salt compounds include diphenyliodonium trifluoromethanesulfonate, bis(4-methoxyphenyl)iodonium trifluoromethanesulfonate, bis(p-tert-butylphenyl)iodonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, (4-methoxyphenyl)diphenylsulfonium trifluoromethanesulfonate and (p-tert-butylphenyl)diphenylsulfonium trifluoromethanesulfonate as well as those substituted by nonafluorobutanesulfonate for the trifluoromethanesulfonate in the above named onium salt compounds.
It is optional in the present invention that the above named various radiation-sensitive acid-generating compounds are used singly or as a combination of two kinds or more. The amount of the radiation-sensitive acid-generating agent as the component (A) in the photoresist composition used in the invention is in the range from 1 to 20 parts by weight per 100 parts by weight of the resinous compound as the component (B). When the amount of the component (A) is too small, formation of a patterned latent image can hardly be accomplished by the pattern-wise light-exposure. When the amount of the component (A) is too large, on the other hand, the photoresist composition in the form of a uniform solution can be obtained only with difficulties or, even if it ever be obtained, the solution suffers a decrease in the storage stability.
It is desirable that the acid-generating agent as the component (A) is selected by taking into consideration the acid-dissociability of the acid-dissociable solubility-reducing groups substituting on the resinous ingredient as the component (B). When the acid-dissociability of the acid-dissociable substituent groups is low as in the resinous compounds belonging to the class (B-2) described later, for example, the component (A) should preferably be selected from those releasing an acid of high acid strength such as the onium salt compounds or, in particular, iodonium salt compounds and sulfonium salt compounds having a fluoroalkyl sulfonic acid ion as the anionic counterpart. When the substituent groups have high acid-dissociability as is the case with (B
2
) in the class (B-1) resinous compounds described later, on the other hand, the component (A) is preferably a diazomethane compound.
The component (B) comprised in the photoresist composition used in the invention is a resinous compound capable of being imparted with increased solubility in an aqueous alkaline solution in the presence of an acid or when interacted by an acid. Suitable resinous compounds to meet the requirement for the component (B) can be classified into two classes of (B-1) and (B-2) described below.
The resinous compound as the component (B) belonging to the class (B-1) i
Kinoshita Yohei
Maemori Satoshi
Nitta Kazuyuki
Oomori Katsumi
Sato Kazufumi
Tokyo Ohka Kogyo Co. Ltd.
Walke Amanda
Wenderoth, Lind&Ponack LLP
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