| 摘要 |
A SIMOX structure having a reduced number of defects is formed by performing a two step anneal. In one embodiment, a conventional anneal is followed by an H2/Si anneal. The conventional anneal first densifies the buried oxide layer in order to make the oxide less reactive with hydrogen. The H2/Si anneal forms a quasi-equilibrium at the superficial semiconductor layer surface, thus there is no etching of the silicon surface and there is only a negligible amount of silicon deposition. The H2 reacts with the oxide precipitates and dissolves them. In a second embodiment the two step anneal comprises a low temperature H2 anneal followed by a conventional anneal. At low temperature, H2 can diffuse through silicon, but is much less reactive. Thus, etching of the superficial silicon and silicon dioxide buried layer is minimal. The conventional anneal is at a higher temperature, thus H2 can react with the oxygen precipitates to remove them.
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