CHARACTERIZATION OF CRYSTALLOGRAPHIC DEFECTS IN THERMALLY OXIDIZED SIMOX MATERIALS

Crystallographic defects present in thermally oxidized SIMOX (separati on by implanted oxygen) materials have been characterized by means of plan view transmission electron microscopy (PVTEM) and defect etching studies. It has been observed that oxidation induced stacking faults ( OISF) are formed in the silicon overlayer of SIMOX substrates during t hermal oxidations at temperatures varying from 900 to 1100 degrees C. In this range of temperature, the OISF length increases continuously w ith time and temperature while the OISF density shows a decrease with oxidation temperature. It has also been observed that at temperatures of 1275 degrees C and higher no OISFs are formed in the silicon overla yer of SIMOX substrates. This behaviour may be explained by a decrease in the flux of interstitials emitted during oxidation due to visco-el astic deformation of the thermal oxide at high temperatures.