Suppressing Al outdiffusion in implantation amorphized and recrystallized silicon on sapphire films

Abstract

In this work we have used a dual implant and anneal process to significantly improve the crystalline quality of 0.3-μm silicon on sapphire films while simultaneously minimizing the outdiffusion of free Al from the sapphire into the Si layer. The crystalline quality, as measured by MeV 4He+ ion channeling closely approached 〈100〉 bulk Si values and the Al concentration, as measured by secondary ion mass spectrometry, was less than 3×1015 cm−3. An explanation for why similar techniques result in large amounts of aluminum outdiffusion when applied to 0.5-μ films is proposed.