RESPUTTERING OF THE SUPERCONDUCTING BI-SR-CA-CU-O THIN-FILMS

Oxygen is normally used as a sputtering gas with or without argon for the sputter deposition of the Bi-Sr-Ca-Cu-O superconductor. Then the grown films are frequently found to have poor qualities by severe resputtering. The purpose of this study is to identify the resputtering particle during the sputter deposition and to investigate its effect on the film growth. The experimental results support the assertion that the resputtering particle is the oxygen anion. We speculate that the oxygen anions pass through the plasma and arrive on the substrate surface nearly in a straight line. The bombardment by the oxygen caused a decrease in the crystallinity and the increase in the surface roughness of the film, and caused the a-axis orientation. A method to prevent the resputtering of the film by the oxygen anions was developed and the very smooth film of the 2212 phase with the c-axis orientation could be grown.