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
2001-12-19
2002-11-12
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
C522S148000
Reexamination Certificate
active
06479213
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a positive photoresist composition for use in the production of semiconductor integrated circuit device, mask for the production of integrated circuit, printed wiring board, liquid crystal panel and the like.
BACKGROUND OF THE INVENTION
In the formation of a pattern for the production of electric 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 is a predominant photoresist until recent years because the sensitivity is high as compared with the positive type and excellent properties necessary for the wet etching are ensured, namely, adhesive property to the substrate and resistance against-chemicals.
However, with the progress of the semiconductor device and the like toward higher densification and higher integration, 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. Particularly, out of the positive photoresists, an alkali development-type positive photoresist using as a base an alkali-soluble novolak resin described, for example, in J. C. Strieter,
Kodak Microelectronics Seminar Proceedings
, 116 (1976), is excellent in the sensitivity, resolution and dry etching resistance and therefore, predominating in the current process.
However, in recent years, the electronic equipment tends to have multiple functions and higher performance and in order to attain higher densification and higher integration, the pattern is strongly demanded to be finer.
More specifically, the integrated circuit is not so much reduced in the vertical dimension as compared with the reduction in the transverse direction, 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 publications also 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 problems 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 the properties both of the resist and the inorganic intermediate layer of the three-layer resist system, namely, a resist having resistance against oxygen plasma, 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 being used as the upper layer resist in the two-layer resist system and the like, particularly an alkali development-system resist for which the current process can be used without any change.
For this, a photosensitive composition obtained by combining an alkali solubility-imparted silicon polymer such as polysiloxane and polysilyl methylene, with a conventional orthoquinonediazide photosensitive material has been proposed and examples thereof include photo-sensitive compositions described in JP-A-61-144639 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-61-256347, JP-A-62-159141, JP-A-62-191849, JP-A-62-220949, JP-A-62-229136, JP-A-63-90534, JP-A-63-91654 and U.S. Pat. No. 4,722,881, and a photosensitive composition obtained by combining an effective amount of an onium salt to a polysiloxane/carbonate block copolymer described in JP-A-62-136638.
These silicon polymers all are imparted with the alkali solubility by the introduction of a phenolic OH group or a silanol group (≡Si—OH). In the case of imparting the alkali solubility by the introduction of a phenolic OH group, the production is very difficult and in the case of imparting the alkali solubility by the silanol group, the aging stability is not sufficiently high or the film loss after the development is disadvantageously large and a rectangular shape cannot be obtained.
Japanese Patent No. 2736939 and JP-A-9-274319 disclose a photoresist containing polysiloxane having within the molecule a group capable of decomposing under the action of an acid. However, these photoresists are disadvantageous in that the resolution is low, a rectangular shape cannot be formed, and the dimensional shift increases at the transfer of the pattern to the lower layer in the subsequent oxygen plasma etching step.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a positive photoresist composition for use in the production of a semiconductor device, which gives a photoresist having high sensitivity and high resolution of 0.2 &mgr;m or less and at the same time, having a rectangular shape.
Another object of the present invention is to provide a positive photoresist composition which is, when used as an upper layer resist in the two-layer resist system, reduced in the dimensional shift at the transfer of the pattern to the lower layer in the oxygen plasma etching step.
Still another object of the present invention is to provide a polysiloxane capable of imparting the above-described excellent properties to a positive photoresist composition.
According to the present invention, the following polysiloxanes and positive photoresist compositions are provided and by these, the above-described objects of the present invention can be attained.
(1) A positive photoresist composition comprising a polysiloxane 1 containing as a copolymerization component at least a structural unit represented by the following formula (I):
wherein L represents a single bond or an arylene group, A′ represents an aromacyclic or alicyclic structure which may have a substituent, and n r
Mizutani Kazuyoshi
Yasunami Shoichiro
Ashton Rosemary
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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