Patent ID: 8070917

Claim:
A reactive sputtering method for application of a bias voltage to a supporting substrate in formation of a film of a metal compound on the supporting substrate according to a bias sputtering method; wherein a supporting substrate conveyor unit and a cathode that includes a target facing the supporting substrate conveyor unit are provided, and the supporting substrate is conveyed between the supporting substrate conveyor unit and the target for formation of a film of a metal compound on the supporting substrate, magnets are provided adjacent to the supporting substrate conveyor unit on a side thereof opposite to that of the supporting substrate, such that a magnetic field is closed and a continuing tunnel part of parallel or nearly parallel arched magnetic force lines forms an oval or a polygon on, the supporting substrate, the magnets each having a first magnetic pole of an S pole or an N pole and a second magnetic pole opposite to the first magnetic pole, the second magnetic pole surrounding the first magnetic pole and, in film formation on the supporting substrate, the magnets are rotated inside a drum in an opposite direction from that in which the supporting substrate is conveyed outside of the drum, so as to secure uniform plasma application along the supporting substrate.