Method of making an oxide superconducting thin film

摘要

A method of making a superconducting thin film of a Y-Ba-Cu-O series material by using a diode parallel plate type sputtering apparatus including a vacuum chamber, a substrate disposed within the vacuum chamber and having a substantially flat surface on which the superconducting thin film is to be formed, and a plate-shaped target functioning as a cathode and disposed within the vacuum chamber to parallelly face to the flat surface of the substrate, the target being made of the same material as the superconducting thin film, a plasma gas being introduced into the vacuum chamber, and a voltage being applied between the cathode and the substrate, wherein the method comprises the steps of applying a high frequency voltage having a frequency higher than 40 MHz between the cathode and the substrate to generate plasma of the introduced gas, superimposing a DC voltage (V) on the high frequency voltage in a polarity that the cathode becomes negative, and setting the DC voltage at a value where the DC voltage is substantially unchanged with variation of a cathode current flowing through the target when adjusting the DC voltage and controlling a value of the DC current while maintaining the DC voltage substantially at the set value.