Rapid thermal processing to improve the epitaxy of (100) silicon on (1102) sapphire.

The heteroepitaxial quality of (100) Si films on (1102) sapphire substrates (SOS) as measured by Rutherford Backscattering (RBS) and x-ray pole figure analysis is improved by a rapid thermal anneal (RTA) after deposition which brings the Si temperature above 1350C for at least several seconds. For a 6000angstrom (100) SOS film the ratio of the RBS yield in the (100) to random direction at the front and back interfaces improves from the as-grown values of 10% and 54%, respectively, to as low as 3.2% and 13% after the RTA. The microtwin volume shows a corresponding decrease to under 1% from the as-grown value of 2.7%. A model based on isothermal solid phase epitaxial regrowth from the untwinned material near the front surface is proposed to account for these results.