Heteroepitaxial SiC films grown in Si by CH 4 plasma immersion ion implantation: Conditions and mechanisms of their formation

Abstract

Thin SiC films in Si are formed by pulse biasing a Si wafer to a high voltage in a methane (CH 4) 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 elucidated by means of Rutherford backscattering spectrometry (RBS), nuclear resonance analysis (NRA) for hydrogen depth profiling and transmission electron diffraction (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 gas as well, has a depth profile, which is not a typical implantation profile. Rather, the hydrogen depth profile is chemically governed by the carbon depth distribution. SiC with its stoichiometry close to unity can trap by far the most hydrogen. Increasing or lowering the C/Si ratio results in a decreasing trapping possibility for hydrogen. The hydrogen depth profile for SiC films also depends strongly on the implantation temperature. Films without hydrogen contamination can be grown at 850°C. TED shows that these films grow heteroepitaxially aligned with the Si matrix.