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
2001-04-06
2003-04-29
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, C430S905000, C430S906000, C430S907000, C430S910000, C430S914000, C526S258000, C526S262000, C526S271000, C526S279000, C526S270000
Reexamination Certificate
active
06555289
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a positive photoresist composition for use in the production of a semiconductor integrated circuit device, a mask for the production of an integrated circuit, a printed board, a liquid crystal panel and the like.
BACKGROUND OF THE INVENTION
In the formation of a pattern for the production of electronic parts of semiconductor device, magnetic bubble memory, integrated circuit and the like, a method of using a photoresist sensitive to ultraviolet ray or visible light has heretofore been widely used in practice. The photoresist includes a negative type photoresist where the area irradiated with light is insolubilized in the developer and a positive type photoresist where the area is solubilized. The negative type photoresist is predominating until recent years because the sensitivity is high as compared with the positive type and the properties necessary for the wet etching are excellent, namely, adhesive property to the substrate and resistance against chemicals.
However, with the progress of high-densification and high-integration semiconductor devices and the like, the pattern is extremely reduced in the line width or space. Furthermore, dry etching is employed for the etching of the substrate and to keep up with this, the photoresist is demanded to have high resolution and high dry etching resistance. Because of these reasons, the positive photoresist occupies the major part at present.
Furthermore, in recent years, with the progress of multifunction and high-performance electronic equipment, a finer pattern is strongly demanded so as to attain higher densification and higher integration.
More specifically, the integrated circuit is not so much reduced in the vertical dimension as compared with the reduction in the transverse direction and therefore, the ratio of the height to the width of the resist pattern must be necessarily large. Due to this, as the pattern becomes finer, the resist pattern on a wafer having a complicated structure with different heights encounters more difficulties in suppressing its dimensional change.
Furthermore, in various exposure systems, a problem arises accompanying the reduction of the minimum dimension. For example, in the exposure by light, the interference action of the reflected light ascribable to the difference in height on a substrate greatly affects the dimensional precision and in the electronic beam exposure, the ratio of the height to the width of a fine resist pattern cannot be increased due to the proximity effect generated by the back scattering of electrons.
It has been found that a large number of these problems can be solved by using a multi-layer resist system. The multi-layer resist system is generally described in
Solid State Technology,
74 (1981) and other than this, many publications report the studies on this system.
In general, the multi-layer resist system includes a three-layer resist system and a two-layer resist system. The three-layer resist system is a method of coating an organic flattening film on a substrate having different heights, superposing thereon an inorganic intermediate layer and a resist, patterning the resist, dry-etching the inorganic intermediate layer using the resist as the mask, and patterning the organic flattening film by O
2
RIE (reactive ion etching) using the inorganic intermediate layer as the mask. In this system, conventional techniques can be fundamentally used, therefore, studies thereon have been started from an early time. However, this system has a problem in that the process is very complicated or since three layers different in the physical properties, namely, organic film, inorganic film and organic film, are superposed, cracks or pinholes are readily generated in the intermediate layer.
As compared with this three-layer resist system, the two-layer resist system uses a resist having properties both of the resist and the inorganic intermediate layer of the three-layer resist system, namely, a resist having resistance against oxygen plasma, and therefore, cracks or pinholes are prevented from occurring. Furthermore, the reduction from three layers to two layers simplifies the process. However, unlike the three-layer resist system where a conventional resist can be used as the upper layer resist, the two-layer resist system must disadvantageously develop a new resist having resistance against oxygen plasma.
Under these circumstances, it has been demanded to develop a high-sensitivity and high-resolution positive photoresist having excellent oxygen plasma resistance and capable of use as the upper layer resist in the two-layer resist system or the like, particularly an alkali development-system resist for which the current process can be used without any change.
In the production of VLSI comprising lines having a width of half micron or less, the wavelength used in the exposure apparatus for lithography becomes shorter and shorter and at the present time, studies are being made even on the use of KrF excimer laser ray or ArF excimer laser ray. In the photolithography using such a short wavelength, a resist called chemical amplification-type resist is generally used.
Particularly, in the case of using ArF excimer laser ray, it is not suitable in view of the optical transparency of the film to introduce a phenol structure into the binder resin as a main component of the resist. The binder generally used is a resin polymer containing, as an image-forming site, a structure capable of decomposing by an acid and generating a carboxylic acid, such as tertiary ester (e.g., tert-butyl ester), 1-alkyladamantyl ester and THP protected entity of carboxylic acid.
As an example of the Si-containing resist having an image-forming site transparent to ArF excimer laser rays, a polymer comprising maleic acid anhydride-unsaturated tert-butyl carboxylate-allyltrimethylsilane-ethoxyethyl methacrylate is disclosed in JP-A-11-231542 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). This resist has a problem in that the resolution in the processing of an ultrafine pattern and the edge roughness of a line pattern are bad. The term “edge roughness” as used herein means a phenomenon that due to the properties of the resist, the edges at the top and bottom of a resist line pattern irregularly fluctuate in the direction perpendicular to the line direction and irregularities are observed on the edges when the pattern is viewed from right above. Furthermore, the coated film has high hydrophobicity and therefore, the exposed area shows poor permeability to an alkali developer, as a result, a large number of development defects are disadvantageously generated.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a positive photoresist composition for use in the production of semiconductor devices, which ensures high resolution, excellent edge roughness of a line pattern, and reduced development defects.
As a result of extensive investigations on the resist composition in the positive chemical amplification system, the present inventors have found that by using an acid-decomposable resin obtained by copolymerizing specific repeating units, the object of the present invention can be attained. More specifically, the present invention provides the following positive photoresist composition.
(1) A positive photoresist composition comprising (A) a resin which comprises (a) a repeating unit represented by formula (I) shown below, (b) at least one repeating unit represented by formula (IIa) or (IIb) shown below, (c) a repeating unit represented by formula (III) shown below and (d) a repeating unit (IV) satisfying the following conditions:
to be copolymerizable with monomers corresponding to the repeating units represented by formulae (I) to (III),
to contain at least one functional group selected from the group consisting of a group containing a lactone structure, a group containing a lactam structure, —OH, —OCH
3
, —OCORa, —NHCORa, —NHSO
2
Ra, —N(R)CORa, —N(R)SO
2
Ra, —COOH, —COORa, —CONHRa, —CONHSO
Mizutani Kazuyoshi
Sasaki Tomoya
Yasunami Shoichiro
Baxter Janet
Fuji Photo Film Co. , Ltd.
Lee Sin J.
Sughrue & Mion, PLLC
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