Comparison of buried oxide in silicon by oxygen implantation made by wafer and beam scanning

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Abstract
Buried oxide in silicon was formed by high dose oxygen implantation using either slow mechanical wafer scanning or the usual rapid beam scanning. Transmission electron microscopy and Auger depth profiling were used to characterize the samples after high‐temperature annealing: 1150 °C for 2 h, followed by 1210 °C for 6 h. Oxygen‐denuded zones of single crystal silicon are formed for both types of samples in the upper region of the top silicon layer (for the wafer‐scanned samples, an oxygen‐denuded zone had not formed after the usual 1150 °C anneal for 2 h). The dislocation density in the top silicon layer was much lower (7 cm−2) for wafer‐scanned samples than for beam‐scanned samples (2×109 cm−2). The density of oxide precipitates in the top silicon layer and of silicon ‘‘islands’’ within the buried oxide was greater for wafer‐scanned samples. These microstructural differences may produce differences in electrical properties.