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
2001-08-14
2004-09-07
Huff, Mark F. (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
C430S281100, C430S270100, C430S326000, C430S328000, C430S330000, C430S331000, C430S905000, C430S914000
Reexamination Certificate
active
06787290
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a positive-working photoresist composition having excellent storage stability to exhibit high pattern resolution and capable of giving a patterned resist layer with well controlled little temperature dependency of size changes by the thermal flow process as well as to a method for the formation of a patterned resist layer by using the same.
In the photolithographic patterning technology in recent years for the manufacture of fine electronic devices, a great variety of chemical-amplification positive-working photoresist compositions are proposed and widely employed by virtue of the excellent pattern resolution and high photosensitivity as compared with conventional positive-working photoresist compositions of old types such as those formulated with a naphthoquinone diazidosulfonic acid ester as the photosensitive ingredient and a novolak resin as the film-forming base resin ingredient. Some grades of the chemical-amplification positive-working photoresist compositions are already under practical applications in the patterning process of the design rule 0.25 to 0.18 &mgr;m.
On the other hand, the technology of semiconductor devices is under an increasing trend toward a higher and higher density of integration and, along with proceeding of mass production of LSIs with a design rule of about 0.15 &mgr;m, the photoresist compositions are required to comply with the demand for patterning of line-and-space patterns, hole patterns and isolated patterns with fineness of 0.12 to 0.18 &mgr;m by using KrF excimer laser beams as the exposure light.
A so-called crosslinked photoresist composition is disclosed in Japanese Patent Kokai 6-148889, 6-230574, 8-62844 and 9-274320 and elsewhere, which is a novel type of chemical-amplification positive-working photoresist composition compounded with a polyvinyl ether or polyvinyloxy compound.
When the crosslinked photoresist composition is applied to a substrate surface followed by a pre-baking treatment to form a dried photoresist layer, a thermal crosslinking reaction proceeds between the polyvinyl ether compound and the base resin ingredient and, by subjecting the photoresist layer to pattern-wise light exposure and post-exposure baking treatment, an acid compound is generated in the resist layer from the acid-generating agent contained therein and the acid acts to dissociate the acid-dissociable solubility-reducing groups in the resinous ingredient and the crosslinks formed in the pre-baking treatment so that the subsequent development treatment with an alkaline developer solution produces a patterned resist layer with high contrast between the exposed and unexposed areas and high pattern resolution where the patterned resist layer has excellent resistance against dry etching.
The above mentioned chemical-amplification positive-working photoresist composition of the crosslinked type, however, has a serious defect of low storage stability that the pattern resolution, cross sectional profile of the excellent patterned resist layer, photosensitivity and other properties of the composition as prepared are subject to degradation within several hours to several days.
As a recent development in the photolithographic patterning technology, the so-called thermal flow process is proposed in Japanese Patent Kokai 2000-188250 for accomplishing an increase in the fineness of the resist pattern by subjecting a patterned resist layer formed by a conventional photolithographic patterning process including the steps of pattern-wise light exposure, post-exposure baking treatment and development to a heat treatment to cause thermal flow of the resist layer.
This thermal flow process is applicable to any conventional photoresist compositions from which a patterned resist layer of improved fineness can be obtained in a relatively simple process without the disadvantage of great investment. On the other hand, this process has a problem that the temperature dependency of the size reduction of the resist pattern is uncontrollably great so that good reproducibility of pattern size reduction can hardly be obtained by the heat treatment of a patterned resist layer formed by development by using a conventional chemical-amplification photoresist composition.
SUMMARY OF THE INVENTION
Under the above described situations, the present invention has been completed with an object to provide a novel and improved positive-working photoresist composition having good storage stability and capable of giving a high-resolution patterned resist layer having excellent resistance against dry etching by applying the thermal flow process with a small dimensional change per unit temperature elevation.
Thus, the positive-working photoresist composition provided by the present invention comprises, as a uniform solution in an organic solvent:
(A) 100 parts by weight of a copolymer of hydroxystyrene as a resinous base ingredient of which at least a part of the phenolic hydroxyl groups or carboxyl groups are substituted for the hydrogen atoms thereof by acid-dissociable groups;
(B) from 1 to 20 parts by weight of a radiation-sensitive acid-generating compound;
(C) from 0.1 to 25 parts by weight of a polyvinyl ether compound having at least two vinyloxy groups in a molecule and susceptible to crosslinking;
(D) from 0.01 to 5 parts by weight of a carboxylic acid compound consisting of atoms of carbon, oxygen and hydrogen alone; and
(E) from 0.01 to 1 part by weight of an amine compound.
Further, the method of the present invention for the formation of a patterned resist layer on the surface of a substrate comprises the steps of:
(a) coating the surface of a substrate with a positive-working photoresist composition defined above followed by drying to form a dried photoresist layer;
(b) exposing the dried photoresist layer on the substrate surface pattern-wise to light to form a latent image of the pattern;
(c) subjecting the photoresist layer after pattern-wise light exposure to a heat treatment;
(d) subjecting the photoresist layer to a development treatment with an aqueous alkaline solution as a developer to form a patterned resist layer; and
(e) subjecting the patterned resist layer to a heat treatment to effect reduction of the pattern size by thermal flow of the resist layer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The photoresist composition of the present invention is a chemical-amplification positive-working photoresist composition in the form of a uniform solution in an organic solvent, of which the resinous base ingredient as the component (A) is a hydroxystyrene-based homopolymeric or copolymeric resin substituted for at least a part of the hydrogen atoms of the phenolic hydroxyl groups or carboxyl groups by acid-dissociable groups.
The acid-dissociable substituent groups on the resinous base ingredient as the component (A) have an effect of decreasing the solubility of the resin in an aqueous alkaline solution and, while the resist layer containing the resin as the component (A) is insoluble in an aqueous alkaline solution, the resist layer is imparted with increased alkali-soluble in the areas pattern-wise exposed to light by interacting with the acid generated and released from the radiation-sensitive acid-generating agent as the component (B) in the light-exposed areas of the resist layer. The acid-dissociable solubility-reducing substituent group on the hydroxystyrene-based polymeric resinous ingredient is not particularly limitative including lower alkoxyalkyl groups, tertiary alkoxycarbonyl groups, tertiary alkoxycarbonylalkyl groups, tertiary alkyl groups and cyclic ether groups as the preferable ones in respect of their acid-dissociability and heat resistance and cross sectional profile of the patterned resist layer obtained from the photoresist composition containing the same.
Examples of the lower alkoxyalkyl groups include 1-ethoxyethyl and 1-methoxypropyl groups. Examples of the tertiary alkoxycarbonyl groups include tert-butoxycarbonyl and tert-amyloxycarbonyl groups. Examples of the tertiary alkoxycarb
Kawana Daisuke
Nitta Kazuyuki
Sato Kazufumi
Shimatani Satoshi
Huff Mark F.
Lee Sin J.
Tokyo Ohka Kogyo Co. Ltd.
Wenderoth Lind & Ponack LLP
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