Zone-Melting Recrystallization of Si Films on SiO2

摘要

Large-area, device-quality Si films on SiO2 have been prepared by zone-melting recrystallization using graphite strip heaters. A composite SiO2/Si3N4 encapsulation layer prevents agglomeration of the molten Si, insures a smooth film surface, and induces (100) texture. The recrystallized films contain widely-spaced grain boundaries, which can be eliminated by seeded growth techniques, and many sub-boundaries within each grain. Sub-boundaries can be entrained along parallel lines underneath a photolithographically defined optical absorber or reflector pattern. Extensive electrical measurements have been made on the recrystallized films. Sub-boundaries have no significant effect on MOSFET device performance, and high-yield CMOS test circuits have been made in films on 2-inch-diameter wafers. Radiation-hardened CMOS devices, lateral bipolar transistors, and dual-gate MOSFETs have been fabricated in recrystallized films.