Defect-minimized SiGe layer using ion beam synthesis

Ion Beam Synthesis for SiGe layers was performed to study the end-of-range(EOR) defects and strain-induced dislocations. High Ge doses of 5×10¹⁶/cm², 3×10¹⁶/cm² and 2×10¹⁶/cm² at 120 keV were implanted to obtain 12 at%, 7 at% and 5 at% of Ge peak concentrations respectively. RBS spectra show a projected range(R_p) at a depth of 65nm and an amorphous thickness of 170nm on a wafer with 12 at% of Ge peak concentration. Ge ion implantation was performed both at room temperature(RT) and at liquid nitrogen temperature(LNT), in order to investigate the effect of implantation temperature on reducing EOR defect density. Solid phase epitaxial(SPE) annealing for all SiGe layers was done in nitrogen ambient at 800°C. The EOR defect density is considerably reduced by LNT implantation and the strain-induced dislocations have a threshold Ge peak concentration(about 6 at%) for their abrupt generation. For SiGe layer with 12 at% Ge peak concentration, the amorphous-crystalline(a/c) interfacial morphology changes from a planar interface into a faceted interface during SPE growth at 550°C.