Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1990-05-23
1992-10-20
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C08F 1820
Patent
active
051570912
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to an ultraviolet-absorbing polymer material. More particularly, this invention relates to an ultraviolet-absorbing polymer material which fits excimer laser working and, when used as a resist material and exposed to the excimer laser, allows formation of a pattern of high resolution with an easy etching operation. This invention further relates to an ultraviolet-absorbing polymer material which possesses high sensitivity to shortwave radiations of not more than 400 nm in wavelength (ultraviolet light, electron beam, and X ray), particularly to the Kr-F laser beam (249 nm) in addition to exhibiting the property mentioned above.
The present invention also relates to a photoetching process. More particularly, the present invention relates to a process for photoetching which is capable of producing patterns of high resolution within 1 .mu.m in line width.
2. Background Art
Generally, in the construction of semiconductor devices such as IC's, LSI's and super-LSI's, the introduction of a desired impurity distribution, namely the control of an impurity distribution, constitutes a very important task. Today the manufacture of such semiconductor devices as mentioned above has advanced to the point at which the accuracy of position of a pn junction parallel to the crystal face relative to the direction of depth is notably improved by the introduction of the technique of impurity dispersion and the accurate distribution of impurity in the direction of crystal face is rendered feasible by the adoption of the technique of selective diffusion capable of covering the portion abhorring diffusion of impurity with a substance impermeable to the impurity during the course of impurity dispersion.
For the formation of the pattern with a substance impermeable to the impurity on the surface of a semiconductor, there has been generally used in most cases an applied photographic technique which comprises coating the surface of a substrate with a resist material, superposing a masking sheet on the layer of the resist material, exposing the masked surface of the layer of the resist material to the light emanating from a light source disposed above, then removing the masking sheet, stripping the layer of the resist material of the sensitized part or non-sensitized part (optionally by the developing treatment), and etching the part of the substrate not covered with the resist material with a solvent. Further, in the manufacture of a semiconductor device, this technique is similarly utilized to advantage as in the formation of an electrode hole, the removal of unfused vacuum-deposited metal after the vacuum deposition of an electrode, and the formation of a gate, for example.
Incidentally, polyalkyl (meth)acrylates represented by polymethyl methacrylate (PMMA) form resist materials possessing high degrees of resolution and have been heretofore finding extensive utility in various applications as resist materials useful with electron beam, far-ultraviolet light, and X ray. In the aforementioned manufacture of a semiconductor device, therefore, the use of these resist materials is expected to allow formation of patterns of high degrees of resolution.
When the resist material of a polyalkyl (meth)acrylate is used in the manufacture of a semiconductor device, however, the resist material is fasted to pose a serious problem from the standpoint of the etching treatment.
As semiconductor devices of the kind described above, silicon devices are preponderantly used today. As the substance impermeable to impurity which is used for covering the surface of a silicon wafer, a SiO.sub.2 film is generally used. A mixed liquid of NH.sub.4 F and HF has been used for etching the SiO.sub.2 film on the silicon wafer and a mixed liquid of hydrofluoric acid (HF) and nirtric acid for etching silicon. Polyalkyl (meth)acrylates are not sufficiently resistant to these etching liquids. When the resist material made of a polyalkyl (meth)acrylate is used, therefore, there arises the possibility that the surfa
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Masataka Murahara
Takeshi Shimomura
Toru Takahashi
Sarofim N.
Schofer Joseph L.
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