AN INVESTIGATION OF AS-IMPLANTED MATERIAL FORMED BY HIGH-DOSE 40 KEV OXYGEN IMPLANTATION INTO SILICON AT 550-DEGREES-C

Device grade [100] single crystal silicon wafers have been implanted w ith 40 keV oxygen ions (O-16+) over the dose range of 1 X 10(17)-8 X 1 0(17)/cm2 at a temperature of 550 +/- 10-degrees-C. Transmission elect ron microscopy, ion channeling, and secondary ion mass spectroscopy st udies show that during implantation the critical dose required to form a buried oxygen-rich amorphous (SiOx, x < 2) layer is lower than 1 X 10(17) O+/cm2. As the dose increases from 1 X 10(17) to 4 X 10(17)/cm2 the thickness of the buried SiOx layer increases and there is a corre sponding decrease in the thickness of the single crystal silicon top l ayer, with the oxygen concentration and residual radiation damage play ing important roles in determining its position and thickness. A dose of 5 X 10(17)/cm2 results in a continuous surface amorphous layer, wit h a buried SiO2 sublayer being formed in the region corresponding to t he implanted oxygen peak. With further increasing dose, the buried SiO 2 sublayer grows primarily towards the surface. The results for the sa mple implanted at a dose of 1 X 10(17)/cm2 show that surface defects c an be attributed to agglomeration of interstitial silicon atoms create d by the internal oxidation process.