Plasma-Enhanced Chemical Vapor Deposition of Silicon Nitride

Abstract

The optimum condition of plasma-enhanced chemical vapor deposition to deposite silicon nitride (SiN x ) film and its application as a gate insulator of a-Si thin-film transistor (TFT) have been investigated. The internal stress of SiN x in the range of 4.3×10 9 dyn/cm 2 tensile to 8.0×10 9 dyn/cm 2 compressive is found to be controllable by changing the ratio of H 2 and N 2 in the source gases without affecting the optical band gap. Satisfactory TFT characteristics and high reliability are realized by using a gate insulator of SiN x having either stoichiometric or N-rich composition which shows the large optical band gap.