Interface Charges at the Back Surface of Silicon Films Seeded

Interface charges at the back of seeded, recrystallized sil icon films on insulating oxide layers were investigated and compared to those at the back of unseeded films. Both the fixed charge density and the interface trap density were found to be appreciably lower for the seeded devices than for unseeded devices. A recrystall ization technique which melted the sil icon film a min imum number of t imes produced the lowest interface charge d nsities. The differences be-tween seeded and unseeded structures may be related to the higher charge densit ies xpected for grain orientations other than {100} or to traps located at the grain boundaries near the back surface of the silicon film. Control of charges at the Si-SiO ~ interfaces in metal-oxide-semiconductor transistors has long been a source of concern for reliable and reproducible device fabrica-tion. In sil icon-on-insulator (SOI) structures, an additional Si-SiO ~ interface is present below the thin silicon film. Charges at the underlying interface can influence the be-havior of MOS transistors in the film. n-Channel transis-tors are especially affected because a positive charge ca