High-dose Ge + implantation into silicon at elevated substrate temperature

Abstract

Germanium ions with a dose of 6 × 10 16 cm −2 and at an energy of 160 keV were implanted into (100) Si wafers at room temperature (RT) and elevated substrate temperatures up to 500°C. Post-implant annealing was performed at 950°C for 1 h in N 2. Experimental results from XTEM micrographs show that the substrate temperature has a considerable effect not only on the as-implanted, but also on the annealed behavior of Ge +-implanted Si. Higher substrate temperatures would be beneficial to improve the crystallinity of surface SiGe layer by the elimination of the surface defects. The influence of different substrate temperatures could be divided into two types. For implantation from RT to 100°C, an amorphous layer still exists in as-implanted silicon, extended dislocations and a high density of surface defects remain in the recrystallized SiGe layer after annealing. For implantation above 200°C up to 500°C, where the amorphous layer could not be generated due to dynamic annealing, a layer of about 150 nm thickness at the surface is nearly defect-free. Only extended disclocations, however large in size and low in density, exist at the depth of 350 nm from surface. No EOR defects were observed in any of the samples.