Identification of BetaSiC Precipitate Formed in p-Type Silicon Single Crystals during Annealing

Abstract

Using high energy reflection electron diffraction, Newman (1) identified a precipitate of PSiC structure below the surface of silicon single crystals annealed in the range of 1000°-1250°C. This structure is cubic with SG: TD2 and ao = 4.358 Å. Most crystals were in the size range: 0.3-0.7μ. PSiC was not detected unless the silicon contained both aluminum and an n-type doping impurity such as phosphorus. Dislocation densities to 3 × 104/cm2 were present.Similar studies at this Laboratory showed that βSiC structure could be detected in silicon single crystals without the presence of aluminum and n-type impurities. In our work, accelerating voltage for electron diffraction was 100 kV; a double condenser was the only lens; camera length was 50 cm; direct beam spot size was 35-50μ at the plate plane. Specimens were p-type (111) Si wafers grown by Czochralski methods; resistivities were 50-60 ohm cm; boron was the major impurity.