Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – Insulative material deposited upon semiconductive substrate
Reexamination Certificate
2001-01-02
2002-09-24
Ghyka, Alexander G. (Department: 2812)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
Insulative material deposited upon semiconductive substrate
C438S781000, C438S680000, C438S681000, C427S489000, C427S569000, C427S412100
Reexamination Certificate
active
06455442
ABSTRACT:
The present invention relates to a process for the preparation of UV protective coatings via plasma-enhanced vacuum deposition, which process comprises using hydroxyphenyl-s-triazines as UV absorbers. This invention also relates to the use of hydroxyphenyl-s-triazines in plasma-enhanced vacuum depositions and to the substrates coated by this process.
The generation of low-temperature plasmas and plasma-enhanced deposition of thin organic or inorganic coatings have been known for some time and have been described, inter alia, by A. T. Bell, “Fundamentals of Plasma Chemistry” in “Technology and Application of Plasma Chemistry”, edited by J. R. Holahan and A. T. Bell, Wiley, N.Y. (1974), and by H. Suhr, Plasma Chem. Plasma Process 3(1),1, (1983).
Such coatings can often be used to specifically change substrate properties. In particular, these processes can bring about surface changes without altering, or even impairing, the other properties of the material very much.
EP-A-0 734 400 describes, for example, the deposition of phosphorus-containing compounds for achieving flame-retarding properties of fibers and fabrics.
U.S. Pat. No. 5,156,882 describes the plasma-enhanced deposition of UV absorbant layers consisting of TiO
2
or other transition metal oxides. One problem in the case of the deposition of inorganic oxides is that the adhesion achieved on polymer substrates is usually only insufficient, thus making it necessary to build up additional intermediate layers of e.g. SiO
2
. The UV absorbant inorganic layers are usually not fully transparent in the visible range which is disadvantageous for many applications.
Attempts have therefore also been made to obtain UV absorbant coatings by depositing purely organic compounds via plasma processes. DE 195 22 865 describes, for example, a PECVD process (“plasma enhanced chemical vapour deposition”) for the preparation of UV absorbant coatings using compounds containing a structural element of formula (A)
JP 6-25448, published on Feb. 1st, 1994, describes a process for the plasma polymerisation of known UV absorbers, such as phenylsalicylates, 2-hydroxybenzophenones, hydroxyphenylbenzotriazoles and cyanoacrylates, on plastic materials.
The plasma-enhanced deposition of organic compounds often results in unpredictable changes of the molecular structures. This is often the case when functional groups, for example OH groups, are present in the molecule. These groups can either be oxidised or deposited. The deposited film can therefore have absorption properties completely different from those of the original compound. Apart from the absorption properties, the photochemical resistance of the deposited compound in the film can also be different from that of the original compound, so that the long-term protection of the deposited film can deviate substantially from that which one would expect when using the original compound in a conventional coating.
Surprisingly, it has now been found that the UV absorber class of the hydroxyphenyl-s-triazines is very particularly suitable for the preparation of UV absorbant layers by plasma-enhanced deposition.
The absorption spectra of the deposited compounds show only a minor change as compared to the spectra in solution, indicating good retention of the molecular structure. They can be evaporated in a wide temperature range without degradation and form, under the conditions of plasma deposition, clear transparent coatings. In combination with a mono- or polyolefinically unsaturated monomer, which is evaporated concomitantly, it is possible to prepare highly adhesive coatings on polymeric substrates.
Because of their good evaporability—without degradation even at higher temperatures—it is also possible to concomitantly evaporate higher molecular weight chromophoric substances such as pigments or dyes and thus to prepare highly UV absorbant coloured coatings.
It is also possible to first deposit the UV absorbers and then to deposit thereon a plasma-enhanced scratch resistant layer of SiO
2
.
In another of its aspects, this invention relates to a process for the preparation of a continuous UV absorbant layer on organic or inorganic substrates via plasma-enhanced vacuum deposition, which comprises evaporating a UV absorber of the hydroxyphenyl-s-triazine class under vacuum while exposing it to a plasma and allowing it to deposit on the substrate.
Preferred substrates are metals, semiconductors, glass, quartz or thermoplastic crosslinked or structurally crosslinked plastic materials.
A semiconductor substrate to be mentioned in particular is silicium which can be present, for example, in the form of wavers.
Metals to be mentioned are in particular aluminium, chromium, steel, vanadium, which are used for manufacturing high quality mirrors such as telescope mirrors or automobile headlight mirrors. Aluminium is particularly preferred.
Examples of thermoplastic crosslinked or structurally crosslinked plastic materials are listed below.
1. Polymers of monoolefins and diolefins, for example polypropylene, polyisobutylene, polybut-1-ene, poly-4-methylpent-1-ene, polyisoprene or polybutadiene, as well as polymers of cycloolefins, for instance of cyclopentene or norbornene, polyethylene (which optionally can be crosslinked), for example high density polyethylene (HDPE), high density and high molecular weight polyethylene (HDPE-HMW), high density and ultrahigh molecular weight polyethylene (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), (VLDPE) and (ULDPE).
Polyolefins, i.e. the polymers of monoolefins exemplified in the preceding paragraph, preferably polyethylene and polypropylene, can be prepared by different, and especially by the following, methods:
a) radical polymerisation (normally under high pressure and at elevated temperature).
b) catalytic polymerisation using a catalyst that normally contains one or more than one metal of groups IVb, Vb, VIb or VIII of the Periodic Table. These metals usually have one or more than one ligand, typically oxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls that may be either &pgr;- or &sgr;-coordinated. These metal complexes may be in the free form or fixed on substrates, typically on activated magnesium chloride, titanium(III) chloride, alumina or silicon oxide. These catalysts may be soluble or insoluble in the polymerisation medium. The catalysts can be used by themselves in the polymerisation or further activators may be used, typically metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, said metals being elements of groups Ia, IIa and/or IIIa of the Periodic Table. The activators may be modified conveniently with further ester, ether, amine or silyl ether groups. These catalyst systems are usually termed Phillips, Standard Oil Indiana, Ziegler (-Natta), TNZ (DuPont), metallocene or single site catalysts (SSC).
2. Mixtures of the polymers mentioned under 1), for example mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (for example PP/HDPE, PP/LDPE) and mixtures of different types of polyethylene (for example LDPE/HDPE).
3. Copolymers of monoolefins and diolefins with each other or with other vinyl monomers, for example ethylene/propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene/but-1-ene copolymers, propylene/isobutylene copolymers, ethylene/but-1-ene copolymers, ethylene/hexene copolymers, ethylene/methylpentene copolymers, ethylene/heptene copolymers, ethylene/octene copolymers, propylene/butadiene copolymers, isobutylene/isoprene copolymers, ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylate copolymers, ethylenetvinyl acetate copolymers and their copolymers with carbon monoxide or ethylene/acrylic acid copolymers and their salts (ionomers) as well as terpolymers of ethylene with propylene and a diene such as hexadiene, dicyclopentadiene or ethylidene-norbornene; and mixtures of such copolymers with
Bauer Michael
Kaufmann Werner
Rytz Gerhard
Ciba Specialty Chemicals Corporation
Ghyka Alexander G.
Stevenson Tyler A.
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