Depth effect of the morphology change induced by hydrogen annealing of grown-in defects in silicon

We study the depth dependence of the morphology of grown-in defects in as-g rown in silicon and after hydrogen annealing. Recently, it has been reporte d through atomic force microscopy observation that the morphology of grown- in defects depends on the thermal annealing temperature. However, it is not possible to fully observe the detailed morphology of grown-in defects from the etched surface. In this paper, we discuss the dependence of the morpho logy of grown-in defects relative to their depth from the surface in silico n crystals after hydrogen annealing at 1200 degrees C for 1 h transmission electron microscopy observation. Near the surface, the morphology of grown- in defects is a 122-sided polyhedral. With increasing depth, the morphology of grown-in defects approaches an octahedron. It is concluded that the mor phology of grown-in defects becomes polyhedral because of oxygen outdiffusi on and the movement of silicon atoms under high temperature annealing. (C) 2000 The Electrochemical Society. S0013-4651(99)12-079-2. All rights reserv ed.