Selective epitaxial growth of Si_(1-x)Ge_x on SiO_2-patterned Si substrate using elemental source molecular beam epitaxy

摘要

The selectrive epitaxial growth (SEG) of Si_(1-x)Ge_x(0.0 <=x<=1.0) on SiO_2-patterned Si(100) substrate was investigated using the elemental source molecular beam epitaxy. The dependence of the behavior of incident Si and Ge atoms was studied on the subtrate temperature and the flux. The fluxes of source beams and the substrate temperatures were in the range of 1.0 x10~(13)-2.9x10~(14)cm~(-2)s~(-1) and 600-800 deg C, respectively. Under SEG condition, the Ge atoms were reevaporated from the oxide surface and were not solely effective in etching SiO_2. However, Ge contributed to etch the oxide layer with accompanying si flux. The etch rate at a Si flux of 1.0x10~(13) cm~(-2)s~(-1) was about 0.85A/min, and then increased to 1.7A/min with accompanying Ge flux of about 2.0x10~(13)cmm~(-2)s~(-1). It was also shown that the SEG of Si_(1-x)Ge_x was achieved by the SiO_2 etch due to the concurrent atomic fluxes of Si and Ge, and in part by the reevaporation of Ge atoms rom SiO_2 surface. The effect of source ions and electrons naturally generated form an electron beam evaporator was also investigated on the SEG characteristics of Ge. The result exhibited that the incident charged particles enhanced the nuceleation of source atoms on SiO_2 surface to negatively affect the SEG of Si_(1-x)Ge_x.