Coating processes – Direct application of electrical – magnetic – wave – or... – Plasma
Reexamination Certificate
1999-11-03
2003-06-03
Turner, Archene (Department: 1775)
Coating processes
Direct application of electrical, magnetic, wave, or...
Plasma
C423S446000
Reexamination Certificate
active
06572936
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hard carbon film-coated substrate which has a hard carbon film formed on a substrate surface and to a method for fabricating the hard carbon film-coated substrate. The present invention further relates to a method for providing a hard carbon film on a substrate, more particularly to a method for providing a protective film such as on inner and outer blades of an electric shaver, magneto-optical disks, thin film magnetic heads and surface acoustic wave (SAW) devices; an antireflection film for lithography; a protective film on sliding surfaces of compressors; or a hard carbon film such as on constituent layers of solar batteries, decorative articles and optical parts.
2. Description of Related Art
It has been conventionally known that the formation of a diamond-like carbon film directly on a substrate results in poor adhesion between the diamond-like carbon film and the substrate. In order to overcome such a disadvantage, proposals have been made which interpose a Si interlayer between the diamond-like carbon film and the substrate (see, for example, Japanese Patent Laying-Open Nos. 2-182880(1990), 3-115572(1991) and 1-138611(1989)).
Japanese Patent Laying-Open Nos. 7-41386(1995) and 7-316818(1995) disclose that the adhesion between a hard carbon film and a substrate can be improved by providing an interlayer of Si, Ru or Ge therebetween even when the substrate is made of a metal or an alloy principally formed of Ni or Al, suitably used such as for an electric shaver blade, or of a stainless steel.
The above-described prior art interlayer is effective in improving adhesion and peel resistance between the substrate and the hard carbon film, e.g. the diamond-like carbon film if interposed therebetween. However, considering the technological abundance in the field and applicability to various technological situations, there still remains a need for the other type of interlayer which is also capable of improving the adhesion and peel resistance between the substrate and the hard carbon film.
The above-described conventional interlayers have been formed by vapor phase epitaxial methods such as a sputtering method and a plasma CVD method. This requires that the thickness of the interlayer be made greater, or alternatively, the substrate position be changed during the interlayer formation if the substrate has a complicated three-dimensional configuration.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a hard carbon film-coated substrate which exhibits improved adhesion and peel resistance between a hard carbon film and a substrate, and a method for providing the hard carbon film-coated substrate.
It is another object of the present invention to provide a method for providing a hard carbon film on a substrate whereby an interlayer can be uniformly formed even on a substrate having complicated three-dimensional configurations and a satisfactory adhesion can be imparted between the hard carbon film and the substrate.
The hard carbon film-coated substrate in accordance with a first aspect of the present invention includes a substrate, a hard carbon film and an interlayer formed between the substrate and the hard carbon film. The interlayer is principally comprised of at least one selected from the group consisting of Al, Cr, Sn, Co and B, oxides, nitrides and carbides thereof.
Any method such as sputtering can be employed to form the interlayer in accordance with the first aspect of the present invention. In the event that the sputtering method is employed, it is preferred to form the interlayer while applying a radio frequency voltage to a substrate so that a self-bias voltage is produced across the substrate. Preferably, the self-bias voltage produced in the substrate is controlled not to exceed −20 V to assure the enhanced adhesion of the hard carbon film to the substrate.
The interlayer in accordance with the first aspect of the present invention may be formed using other physical deposition or chemical vapor phase epitaxial methods. Plating may be employed to form a metallic interlayer, for example.
The term “hard carbon film” as used in the first aspect of the present invention is intended to include an amorphous diamond-like carbon film, a diamond-like carbon film having amorphous and crystalline portions, and a crystalline diamond-like carbon film.
A method of forming the hard carbon film in the first aspect of the present invention is not particularly limited. The hard carbon film can be formed such as by a CVD method, e.g. a plasma CVD method. Analogously to the interlayer formation, it is preferred to form the hard carbon film while applying a radio frequency voltage to a substrate so that a self-bias voltage is produced across the substrate. Preferably, the self-bias voltage produced in the substrate is controlled not to exceed −20 V. In the plasma CVD method, an electron cyclotron resonance (ECR) plasma CVD apparatus can be employed as a means for generating a plasma, for example. The use of such an apparatus increases a plasma density and enables a high-quality hard carbon film to be formed at low temperatures.
The hard carbon film-coated film in accordance with the first aspect of the present invention is applicable to inner and outer blades of an electric shaver, for example. Those inner and outer electric shaver blades are typically formed of a metal or an alloy principally comprised of Ni or Al, or of a stainless steel. Accordingly, a substrate formed of these materials can be employed as a substrate in the first aspect of the present invention.
The substrate is not limited to the inner and outer blades of an electric shaver, but is also applicable to magneto-optical disks, thin film magnetic heads and surface acoustic wave (SAW) devices. The hard carbon film may be provided thereon to serve as a protective film therefor. Also, the hard carbon film may be provided to serve as an antireflection film which can be used during exposure in a lithography method. Furthermore, the hard carbon film may be provided to serve as a protective film for sliding parts of a compressor such as a rotary compressor, as a solar cell protective film layer, as an optical part, or as a part of decorative articles.
The material types of the substrate in accordance with the first aspect of the present invention include cast irons such as Mo—Ni—Cr cast irons, steel such as high-speed tool steel, stainless steel such as SUS 304, ferrous alloys, non-ferrous metallic materials, ceramics, noble metals, and carbons. The non-ferrous metallic materials and ceramics include a single, alloy or sintered form of Ti, Al, Zr, Si, W, Mo, In, Ta, Fe, Ni, Co, Mn, Cr or Zn; and oxides, nitrides and carbides thereof. The noble metals include Au, Ag, Pt, Ru and Pd. The carbons include aluminum-impregnated carbons.
A method for providing a hard carbon film on a substrate, in accordance with the second aspect of the present invention, includes the steps of forming an interlayer on the substrate by plating and forming the hard carbon film on the interlayer.
In accordance with a narrower, second aspect of the present invention, a method includes the steps of deposition-forming a substrate on a mold through electroforming, forming an interlayer on the substrate by plating, and forming a hard carbon film on the interlayer.
In the step of forming the interlayer by plating, the interlayer can be formed while the substrate is held on the mold. This eliminates the necessity of disengaging the substrate from the mold to thereby increase the productivity of the resulting hard carbon film-coated articles.
The hard carbon film in accordance with the second aspect of the present invention includes an amorphous diamond-like carbon film and a diamond-like carbon film containing crystallites. It further includes a crystalline diamond-like carbon film.
In the second aspect of the present invention, a method of forming the hard carbon film is not particularly limited. The hard carbon film can be formed suc
Domoto Yoichi
Hirano Hitoshi
Kiyama Seiichi
Kuramoto Keiichi
Rader & Fishman & Grauer, PLLC
Sanyo Electric Co,. Ltd.
Turner Archene
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