Comparison of properties of solid phase epitaxial silicon on sapphire films recrystallized by rapid thermal annealing and furnace annealing

Chemically vapour deposited silicon on sapphire (SOS) films 0.25 μm thick were implanted with 28Si+ and recrystallized in solid phase by furnace annealing (FA) and IR rapid thermal annealing (RTA) in our laboratory. An improvement in crystalline quality can be obtained using both annealing procedures. After FA, it is hard to retain the intrinsic high resistivity value (104–105 Ω cm) observed in as-grown SOS films, so the improvement process cannot be put to practical use effectively. However, it is demonstrated that by properly adjusting the implantation and RTA conditions, significant improvements in both film quality and film autodoping can be accomplished. This work describes a modified double solid phase epitaxy process in which the intrinsic high resistivities of the as-grown SOS films are retained. The mechanism of suppression of Al autodoping is discussed.