Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
1998-12-03
2001-04-24
McDonald, Rodney (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S298070, C204S298090, C204S298190, C204S298200
Reexamination Certificate
active
06221217
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates in general to the field of magnetron sputtering systems, and more particularly to a high magnetic flux cathode apparatus and method for high productivity physical vapor deposition.
BACKGROUND OF THE INVENTION
The deposition of films using a magnetron sputtering system provides enhanced deposition rates through the creation of a magnetic field at the target surface. It is advantageous in magnetron sputtering systems to increase the magnetic field strength at the target surface. This can be especially true when the target is a magnetic material.
One barrier to the strength of the magnetic field is the backing plate upon which the target is bonded. The backing plate serves the purpose of cooling the target and providing part of the chamber wall for forming the vacuum chamber for deposition of the target onto a substrate. In conventional systems, the backing plate experiences a pressure differential from the vacuum chamber to atmospheric pressure. This pressure places limits on the material properties of the backing plate.
Conventional systems have attempted to increase the magnetic field at the target using a number of methods. Some conventional systems have attempted to strengthen the magnetic field at the target by decreasing the thickness of the backing plate. However, bowing, deflection and buckling of the backing plate can be caused by the pressure differential between the vacuum inside the chamber and atmospheric pressure outside the chamber.
SUMMARY OF THE INVENTION
In accordance with the present invention, a high magnetic flux cathode apparatus and method for high productivity physical vapor deposition is provided that substantially eliminates or reduces disadvantages and problems associated with previously developed magnetron sputtering systems.
According to one embodiment of the present invention, a magnetron sputtering system is provided that includes a backing plate with cooling channels. The magnetron sputtering system also generates low pressure region in the magnetron assembly such that the backing plate sees a pressure differential much lower than atmospheric pressure. The backing plate is reduced in thickness and provides less of a barrier to the generated magnetic field on the target. In another embodiment, the present invention includes a backing plate supported with a center post.
A technical advantage of the present invention is the thinning of the backing plate to provide less of a barrier to the magnetic field generated by the magnet array, thus increasing the magnetic field seen by the target.
A further technical advantage of the present invention is the use of a cooling fluid to cool the backing plate and the target by circulating the cooling liquid through cooling channels in the magnetron assembly.
An additional technical advantage of the present invention is the use of low-vapor-pressure liquid in the magnetron assembly so that the liquid does not evaporate at the lower pressures therein.
Still another technical advantage of the present invention is the use of low pressure region in conjunction with a thin backing plate to reduce buckling, bowing and deflection of the backing plate.
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Davis Cecil J.
Heimanson Dorian
Moslehi Mehrdad M.
Omstead Thomas R.
CVC, Inc.
Gary Cary Ware & Freidenrich LLP
McDonald Rodney
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