Sputtering apparatus

1 . A sputtering apparatus for applying a thin film coating to a substrate comprising:

a vacuum chamber;

at least two cylindrical targets or two planar targets in the vacuum chamber; and

at least two magnets each juxtaposed respectively to each of the targets so as to generate a magnetic field in a vicinity of an outer surface of the target,

wherein:

(i) the thin film coating is formed by applying a voltage to each of the targets while a discharge gas and a reactive gas are introduced into the vacuum chamber,

(ii) Formula (1) is satisfied in the vacuum chamber,

d 1≦3 d 2  Formula (1)

provided that d1 is a distance between the outer surfaces of the two targets and d2 is any one of distances between the outer surfaces of the targets and the substrate.

2 . The sputtering apparatus of claim 1 , wherein, Formula (2) is satisfied in the vacuum chamber.

d 1≦2 d 2  Formula (2)

3 . The sputtering apparatus of claim 1 , wherein, Formula (3) is satisfied in the vacuum chamber.

θ≦160  Formula (3)

provided that:

(i) when the two targets are cylindrical, θ is defined as an angle between two normal lines drawn on outer circles of the targets in a cross-section plane containing the two targets, which is perpendicular to a side surface of one of the cylindrical targets, each normal line being drawn at a point where the magnetic field is strongest in the outer circle; and

(ii) when the two targets are planar, θ is defined as an angle between two perpendicular lines of the targets in a cross-section plane containing the two targets, which is perpendicular to a side line of one of the planar targets.

4 . The sputtering apparatus of claim 3 , wherein, Formula (4) is satisfied in the vacuum chamber.

45°≦θ≦100°  Formula (4)

5 . The sputtering apparatus of claim 1 , wherein, the targets are cylindrical and the targets rotate in circumferential directions while sputtering.

6 . The sputtering apparatus of claim 1 further comprising a protection container which surrounds the targets and has an aperture open to a front,

wherein, the protection container has a discharge gas inlet on a back wall, while a reactive gas inlet is provided at a portion of the vacuum chamber between the targets and the substrate.

7 . The sputtering apparatus of claim 1 , wherein, polarities of electrical power supplied to the two targets are different from each other and change with time.