Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2001-01-18
2002-07-16
Ver Steeg, Steven H. (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S298080, C204S298170, C204S298230, C204S298280
Reexamination Certificate
active
06419800
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a film-forming apparatus that forms an optical film on optical members by sputtering in a vacuum apparatus with an adjustable reduced pressure atmosphere, to a method therefor and to film-formed substrates with films formed thereby.
DESCRIPTION OF THE PRIOR ART
It has been attempted in the past to place two sputtering targets adjacently on the same plane on respective cathodes, and coat the substrate with a coating comprising the components of the target material. In such cases, the method adopted is to provide each cathode with a power source for application of a negative voltage to the cathodes, i.e., to supply a negative voltage to each cathode with electrically separate systems.
This has been developed in recent years into an apparatus such as shown in
FIG. 13
, where alternately reversed voltages are applied to two targets on the same plane and a film is formed on a substrate while destaticizing the targets.
In the abbreviated cross-sectional view of a film-forming apparatus shown in
FIG. 13
, argon gas or, if necessary, oxygen, nitrogen, methane, alcohol, a hydrocarbon, fluorocarbon or other gas is introduced into the film-forming apparatus through a gas introduction tube (not shown), while the inside of the film-forming apparatus is simultaneously evacuated with an evacuation pump (not shown) to prepare a space reduced to a given pressure; when a negative voltage is applied from the power source
7
to the cathodes
1
A,
1
B arranged in a row, the glow discharge plasma
3
produced on the surface of the respective targets
2
A,
2
B situated on each cathode
1
A,
1
B accomplishes sputtering of the target
2
A and the target
2
B. When the cathode
1
A is a positive electrode, the cathode
1
B is a negative electrode. When the cathode
1
A is a negative electrode, the cathode
1
B is a positive electrode.
A gas retainer plate/anti-adhesion plate/film thickness control plate
6
is mounted surrounding the two cathodes
1
A,
1
B, and this prevents unnecessary flying of the sputtered particles while also closing off spread of the plasma
3
to stabilize the process. A substrate
4
on which the film is to be formed is situated at a position opposite the target
2
A and target
2
B outside the openings of the gas retainer plate/anti-adhesion plate/film thickness control plate
6
. The substrate
4
is conveyed in the same direction as the direction in which the pair of targets
2
A,
2
B are oriented.
A magnetron power source
7
applies a negative voltage to the cathodes
1
A and
1
B. At this time, an oscillator, switching circuit or AC electric generator
8
alternately reverses the polarity of the cathodes
1
A and
1
B so that the cathode
1
B is the positive electrode when the cathode
1
A is the negative electrode and so that the cathode
1
A is the positive electrode when the cathode
1
B is the negative electrode, to destaticize the charge accumulated on the surface of the targets
2
A,
2
B, while from an instantaneous point of view, the alternating reverse glow discharge plasma
3
produced by applying a negative voltage to one of the cathodes
1
A or
1
B and a positive voltage to the other of the cathodes
1
B or
1
A causes sputtering of the targets
2
A and
2
B situated on the surfaces of the two cathodes
1
A and
1
B.
On the other hand, there are methods for forming films on the ends of optical three-dimensional parts by vacuum evaporation, whereby films can be coated on the ends or sides of numerous small optical (three-dimensional) parts, which uses the combined effect of rotating a dome loaded with the optical parts and using activating means such as a plasma assist.
Problems to be Solved by the Invention
There has been a limit to the number of optical parts that can be charged by the aforementioned optical part vacuum evaporation process, and productivity has not been very high.
In addition, there are also limits on the materials that can be used for conventional film formation by such vacuum evaporation, and in principle compounds comprising elements of different vacuum evaporation pressures have different vacuum evaporationization rates for each element, such that composition of the vacuum evaporation source has often differed from the composition of the film.
It is an object of the present invention to provide a film-forming method for fabrication of compact optical parts using a bell jar (or “carousel-shaped”) apparatus whereby the number of parts that can be placed in the apparatus at a time can be increased, and to provide an apparatus therefor.
SUMMARY OF THE INVENTION
The aforementioned objects of the invention can be achieved by the following construction.
(1) A film-forming apparatus comprising a magnetron sputtering cathode, a target situated on the cathode and a film-forming substrate positioned opposite the target, in a vacuum apparatus with an adjustable reduced pressure atmosphere, the film-forming apparatus characterized by being provided with a pair of cathodes located proximally to each other and situated in a straight line in the direction perpendicular to the conveying direction of the substrate, with at least one row situated in the conveying direction of the substrate, and a power source device (a power source, an oscillator, switching circuit or AC electric generator etc.) that alternately reverses the polarity of the pair of cathodes so that when the first of the pair of cathodes is used as a negative electrode the second of the pair of cathodes is used as a positive electrode, and when the second of the pair of cathodes is used as a negative electrode the first of the pair of cathodes is used as a positive electrode, in order to apply a glow discharge-producing voltage to a pair of targets corresponding to each of the pair of cathodes, situated on the surface of each cathode.
(2) A film-forming method in which a magnetron sputtering cathode, a target situated on the cathode and a film-forming substrate positioned opposite the target, are situated in a vacuum apparatus with an adjustable reduced pressure atmosphere, to form a film on the surface of the substrate, the film-forming method being one which comprises situating a pair of cathodes located proximally to each other in a straight line in the direction perpendicular to the conveying direction of the substrate, with at least one row situated in the conveying direction of the substrate, alternately reversing the polarity of the pair of cathodes so that when the first of the pair of cathodes is used as a negative electrode the second of the pair of cathodes is used as a positive electrode, and when the second of the pair of cathodes is used as a negative electrode the first of the pair of cathodes is used as a positive electrode, in order to apply a glow discharge-producing voltage to a pair of targets corresponding to each of the pair of cathodes, situated on the surface of each cathode, and simultaneously sputtering the pair of targets by the produced glow discharge to form a film comprising the structural material of the targets on the surface of the substrate.
(3) A film-formed substrate characterized by being obtained by the film-forming method of (2) above.
It is preferred to provide an oscillator, switching circuit or AC electric generator between the power source and cathodes for alternate reversal of the polarity of the pair of cathodes. In the film-forming apparatus of the invention, as shown by the plan view of the surfaces of the targets
2
A,
2
B in
FIG. 1
, the pair of targets
2
A,
2
B are situated adjacent to each other and they are arranged serially in the direction perpendicular to the conveying direction, with at least one row situated in the conveying direction of the substrate
4
.
The film-forming apparatus of the invention, in which the pair of targets
2
A,
2
B are situated adjacent to each other and they are arranged serially in the direction perpendicular to the conveying direction, with at least one row situated in the conveying direction of the substrate, alternately reverses the pola
Anzaki Toshiaki
Mori Kenji
Conlin David G.
Edwards & Angell LLP
Jensen Steven M.
Nippon Sheet Glass Co. Ltd.
Ver Steeg Steven H.
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