Back Channel Degradation and Device Material Improvement by Ge Implantation

Because of potential “back channel” leakage problems in silicon-oninsulator (SOI) metal-oxide-semiconductor (MOS) devices, especially n-channel MOS devices which must operate in an ionizing radiation environment, it is desirable to produce Separation by IMplantation of OXygen (SIMOX) wafers which have a layer of poor quality silicon near the Si/buried SiO2 interface. At the same time, these wafers must have low defect, high quality silicon near the wafer surface for device fabrication.We have demonstrated that with Ge ion implantation and solid phase epitaxy regrowth, the surface region of the silicon top layer of the SIMOX wafer is improved and the region adjacent to the buried SiO2 is degraded. These results have been observed by RBS/channeling, XTEM, and plane view TEM.