Growth of the carbide, nitride and oxide of silicon by plasma immersion ion implantation

Plasma immersion ion implantation (PIII) has been applied to the formation of silicon carbide, silicon nitride and silicon oxide thin films on Si, offering the possibility of growth on three-dimensional objects. SiC is a semiconductor that is applicable in high-temperature, high-frequency and high-power electronics. Si3N4 and SiO2 are insulators, which are also necessary for semiconductor design. The thin films on Si were formed by pulse-biasing Si wafers in methane (CH4), ammonia (NH3), nitrogen (N2), water (H2O) and oxygen (O2) RF plasmas. The composition of the resulting layers as a function of the preparation conditions—namely the implantation temperature and the number of pulses received by the wafers—was elucidated by means of Rutherford backscattering spectrometry (RBS) and, for H depth profiling, nuclear resonance analysis (NRA). We have shown that, using CH4 PIII, all C/Si ratios from 0 to ∞ can be obtained, whereas for N2, NH3, O2 and H2O implantation, a saturation concentration of nitrogen and oxygen, in the range of the stoichiometric nitride and oxide, exists. Using the H-containing precursor gases, higher saturation concentrations are always observed compared to the pure O2 and N2 precursors. The trapping behavior of H is strongly dependent on the precursor gas used and is most pronounced for CH4, followed by H2O and NH3. However, H incorporation can be avoided by increasing the implantation temperature.