Effect of annealing on the defect structure in a-SiC:H films

The annealing behavior of amorphous, hydrogenated silicon carbide films in the range 400-900 degrees C was studied by optical characterization methods, N-15 hydrogen profiling, and defect profiling using a variable energy positron beam. The films were deposited in an electron cyclotron resonance chemical vapor deposition system using ditertiary butyl silane [SiH2(C4H9)(2)] as the monosource for silicon and carbon. As-deposited films were found to contain large concentrations of hydrogen, both bonded and unbounded. Under rapid thermal annealing in a N-2 atmosphere, the bonded hydrogen effuses giving rise to additional Si-C bond formation and to film densification. After annealing at high temperatures in N-2, a marked decrease in the total hydrogen content is observed. After annealing in vacuum, however, the hydrogen effusion promotes void formation in the films. (C) 1996 American Institute of Physics.