Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2000-08-04
2001-12-11
Nguyen, Nam (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S298060, C204S298120, C204S298140, C204S298260
Reexamination Certificate
active
06328857
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method for forming a coating on an entire surface of a substrate by sputtering in a vacuum apparatus equipped with a film-forming chamber capable of controlling a vacuum atmosphere, and a sputtering apparatus used to carry out the method.
BACKGROUND OF THE INVENTION
A sputtering technique has conventionally been attempted in which two sputtering cathodes having a target attached thereto are adjacently arranged and a coating comprising the target material is formed on a substrate moving in one direction in front of the targets. In this case, a method has been employed that power sources for applying a negative voltage to the two cathodes are provided with respect to the respective sputtering cathode, and a negative voltage is applied to each cathode through electrically separate lines.
This technique has recently developed into a DMS method in which an inversion voltage is alternately applied to the two sputtering cathodes adjacently arranged and while destaticizing the targets, a coating is formed on the substrate moving in one direction in front of the targets. The DMS method is used as a method suitable to high-rate sputtering.
In order to cover the entire surface of a bulky substrate or both sides of a flat plate-like substrate simultaneously with a coating, the sputtering apparatus must be provided with a driving part so as to coat the substrate while rotating the substrate. On the other hand, electron beam deposition or arc plasma ion plating which achieves a high coating rate and can coat a wide area has problems such that the substrate material to be coated is limited and the composition of the coating is deviated from that of the evaporation material because a component or an element, having different vapor pressure has a different rate of evaporation. It has therefore been demanded to develop a sputtering technique and an apparatus therefor that can form a coating on the entire surface of a substrate by a sputtering method which is relatively free from those problems.
SUMMARY OF THE INVENTION
The present invention has been made to overcome the above-described conventional problems.
One object of the present invention is to provide a method for forming a coating of various metal oxides, nitrides, etc., on the entire surface of a bulky substrate or on both sides of a flat plate-like substrate at a high rate.
Another object of the present invention is to provide a sputtering apparatus for carrying out the coating formation method.
According to one embodiment of the present invention, there is provided a method for forming a coating on a substrate, which comprises setting at least one pair of sputtering cathodes as coating cathodes in a film-forming chamber capable of controlling a vacuum atmosphere and applying a voltage to each pair of the sputtering cathodes by alternately inverting their polarities such that when one cathode functions as a cathode, another cathode functions as an anode, and when the another cathode functions as a cathode, the one cathode functions as an anode, sputtering targets attached to the coating cathodes by a glow discharge induced between the two sputtering cathodes of the one pair of coating cathodes, and forming a coating on a substrate disposed substantially in front of the targets attached to the coating cathodes.
According to the present invention, the coating can be formed on both sides of a flat plate-like substrate at the same time. Since the polarity of the potential applied to each sputtering cathode alternates between positive and negative, the target surface is always destaticized even where the target is an electrically insulating substance such as a metal oxide, and as a result, electrification phenomenon does not occur. This enables both sides of a substrate to be simultaneously coated with an insulating metel oxide film. Further, even where the substrate has a bulky shape, such as a spherical shape or a columnar shape, a coating can be formed over the entire surface of the substrate.
REFERENCES:
patent: 5611899 (1997-03-01), Maass
patent: 6096174 (2000-08-01), Teschner et al.
patent: 6103320 (2000-08-01), Matsumoto et al.
Merriam Webster's Collegiate Dictionary, Tenth Edition, 1996, p. 14.
Anzaki Toshiaki
Ogino Etsuo
Nguyen Nam
Nippon Sheet Glass Co. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
VerSteeg Steven H.
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