Patent ID: 7220315

Claim:
A method of producing a polycrystalline thin film on a film forming surface of a polycrystalline substrate, the polycrystalline thin film comprising oxide crystal grains having a C-type rare earth crystal structure represented by a formula Yb 2 O 3 and showing a value of full width at half maximum of 20° or less in X-ray diffraction with the θ-2θ method, the method comprising: depositing constituent grains emitted from a target comprising constituent elements of the polycrystalline thin film; setting a temperature of the polycrystalline substrate within a range from 150° C. to 250° C. during depositing the constituent grains; generating an ion beam of at least one of Ar + , Kr + , and Xe + from an ion source; adjusting the ion beam energy of the ion beam within a range from 175 eV to 225 eV; and irradiating the ion beam, having the adjusted ion beam energy, on the film forming surface of the substrate at an angle of incidence from 50° to 60° with respect to the normal of the film forming surface while depositing the constituent grains on the substrate.