Patent ID: 7198700

Claim:
A method of forming a thin film comprising the step of: forming an AgPd alloy thin film using a sputtering target material, the AgPd alloy thin film comprising Pd in an amount ranging from 0.5 to 2.5 atomic % and Cu in an amount ranging from 0.1 to 3.5 atomic % wherein the thin film has a reflection coefficient of 70% or more for light having a wavelength of 400 nm or more, the sputtering target material comprising an AgPd alloy in which palladium is disposed at grain boundaries of the silver, the disposition of the palladium at the grain boundaries of the silver having been effected at the time of preparation of the AgPd alloy by adding a given quantity of palladium to silver and dispersing the palladium into grain boundaries of the silver in a uniform manner.