PURPOSE: To form a thin film having a gradient structure of arbitrary composition by making target temp. variable by means of the temp. of a fluid flowing through a backing plate and the irradiation of a target surface with a ray of light.
CONSTITUTION: A fluid 3 is circulated through a backing plate 2 of a target 1, and the temp. of the fluid 3 is regulated to an arbitrary temp. by means of an external temp. controller. Further, the surface of the target 1 is irradiated with a ray of light from a light source 4, such as infrared ray lamp, to heat the target 1 surface. By using this device and forming the target 1 into a powder of Bi oxide, a thin film is deposited onto a base material 5 by means of high frequency sputtering. At this time, if the change in the temp. of the fluid 3 is made gradual with respect to deposition velocity, the gradient distribution of composition can be formed in a film thickness direction. If the temp. of the fluid 3 is kept constant and the target 1 surface is heated by irradiation with a ray of light, the composition of the deposited film is momentarily changed and a steep laminated film interface can be attained.