Heteroepitaxial SiC films grown in Si by CH4 plasma immersion ion implantation: Conditions and mechanisms of their formation

Thin SiC films in Si are formed by pulse biasing a Si wafer to a high volta ge in a methane (CH4) RF plasma (plasma immersion ion implantation, PIII). The composition and structure of the resulting layers in dependence on the preparation conditions - mainly the implantation temperature - are elucidat ed by means of Rutherford backscattering spectrometry (RBS), nuclear resona nce analysis (NRA) for hydrogen depth profiling and transmission electron d iffraction (TED). It is shown that by using PIII all C/Si ratios from 0 to 1/0 can be obtained. The hydrogen, which is implanted from the precursor ga s as well, has a depth profile, which is not a typical implantation profile . Rather, the hydrogen depth profile is chemically governed by the carbon d epth distribution. SiC with its stoichiometry close to unity can trap by fa r the most hydrogen. Increasing or lowering the C/Si ratio results in a dec reasing trapping possibility for hydrogen. The hydrogen depth profile for S iC films also depends strongly on the implantation temperature. Films witho ut hydrogen contamination can be grown at 850 degreesC. TED shows that thes e films grow heteroepitaxially aligned with the Si matrix. (C) 2001 Elsevie r Science B.V. All rights reserved.