Residual strain and defects in solid phase epitaxial regrown Si and SiGe on sapphire and device applications.

摘要

This work represents the first systematic study of the effect of solid phase epitaxial (SPE) regrowth on the physical material properties of silicon on sapphire (SOS). Implanted SOS samples were subject to various heat treatments and the residual material strain analyzed using X-ray diffraction. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied to catalog residual defects and study surface morphology. The residual strain in the SPE SOS film can be predicted by the thermal expansion mismatch between the silicon and the sapphire, although sufficient time at temperature is required for the silicon to fully relax. Higher temperature anneals provide a significant reduction in residual defect densities. The defects which remain after the high temperature anneals appear to be correlated with the original twinning defects in the film during the island dominated deposition.; The deposition of SiGe directly on sapphire was also studied. This work represents the first known deposition of single crystal SiGe directly on sapphire using rapid thermal chemical vapor deposition (RTCVD). Substrate surface history was found to effect the orientation of the epitaxial SiGe film. SiGe with an (011) orientation was found to deposit on new sapphire substrates, whereas substrates which had been damaged using an implant or a plasma etch favored (001) oriented SiGe.; The first reported CMOS FET test structures were fabricated in SiGe on SOS and tested for both DC and high frequency characteristics. It is clear from the results that a modest increase in p-FET is realized.