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
2000-10-30
2003-01-14
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
C430S281100, C430S286100, C430S905000, C526S281000, C526S319000, C526S321000
Reexamination Certificate
active
06506535
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a positive working photoresist composition for use in the production of semiconductor integrated circuit devices, mask for the production of integrated circuits, printed wiring boards, liquid crystal panels and the like.
BACKGROUND OF THE INVENTION
In the formation of a pattern for the production of electric parts of a semiconductor device, a magnetic bubble memory, an 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 working photoresist where the area irradiated with light is insolubilized in the developer, and a positive working photoresist where the area is solubilized. The photoresist has been predominated by the negative working photoresist until recent years because the sensitivity of the negative working photoresist is higher than that of the positive working photoresist and also is favored with excellent properties necessary for the wet etching, 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 working photoresist occupies the major part at present. Particularly, out of the positive working photoresists, an alkali development-type positive working photoresist using as the 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, formation of a finer pattern is strongly demanded.
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 in general is described in
Solid State Technology,
74 (1981) and other publications also report studies on this system.
Generally, 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 foil 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 working 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.
In the production of ultra-LSI 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 on the use of KrF eximer laser ray or ArF eximer laser ray. In the formation of a pattern for lithography using such a short wavelength, a resist called chemical amplification-type resist is generally used.
Particularly, in the case of using ArF eximer laser rays, 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 such that 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 or THP protected entity of carboxylic acid, is contained as the image-forming site. The Si-containing polymer containing an image-forming site transparent to ArF eximer laser rays is disclosed, for example, in JP-A-8-160623 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-10-324748, JP-A-11-60733 and JP-11-60734.
SPIE,
Vol. 3678, Item 241, discloses a chemical amplification-type resist using a vinyl polymer containing a tris(trimethylsilyl)silylethyl group at the acid-decomposable ester terminal. Also,
SPIE,
Vol. 3678, Items 214 and 562, discloses a chemical amplification-type resist using a vinyl polymer containing a trimethyl-bis(trimethylsilyl)disilaheptylmethylpropyl ester at the acid-decomposable ester terminal. However, these techniques have a problem in the exposure margin. The term “exposure margin” as used herein means a phenomenon such that when the exposure amount is changed, the line width of the pattern obtained is changed in accordance therewith.
The storage stability of the resist solution is also in need of improvements. For example, when a chemical amplification-type photoresist is stored in the liquid state, due to the poor compatibility between the resin and the photo-acid generator, particles may be generated in the solution or the resist performance may be deteriorated.
Also, the above-described techniques have a problem in the defocus latitude depended on line pitch. Recent devices have a tendency to contain various patterns, therefore, the resist is required to have various capabilities. One of these capability is the defocus latitude depended on line pitch. More specifically, a device has a portion where lines are crowded, a pattern where the space is broad as compared with lines, and isolated lines. Therefore, it is important to resolve various lines with high reproducibility. However, reproduction of various lines cannot be easily
Kodama Kunihiko
Mizutani Kazuyoshi
Sato Kenichiro
Baxter Janet
Clarke Yvette M.
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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