Electrochemical etching used on UHV/CVD epitaxial thin films

Abstract

Ultra High Vacuum Chemical Vapor Deposition (UHV/CVD) is carried out to deposit silicon. The deposition is carried out in the temperature range of 550 to 800/spl deg/C. Electrochemical etching is used to test the defects in epitaxial films. Two different ways of etching were performed to validate the thin film etching. The results is almost the same. The defects are visible by the microscope at about 600/spl times/. It is found that the film quality is good in two extreme temperature ranges, i.e. 500 to 700/spl deg/C and above 750/spl deg/C, which was also observed by other authors. The defect density is estimated to be in the order of 10/sup 6/ to 10/sup 8/ cm/sup -2/, including line defects, even micro-defects because of the poor environment cleanliness.