SILICON-ON-INSULATOR PRODUCED BY HELIUM IMPLANTATION AND THERMAL-OXIDATION

A novel technique that produces a high quality low cost silicon-on-insulator is described. The method takes advantage of the formation of a buried porous layer in silicon implanted with light ions. Trenches are then formed in such a way that O2 can be transported into the cavities. Finally, an oxidation in dry O2 produces a buried oxide layer. Helium ions at energies of 40 or 300 keV and fluences up to 2×1017/cm2 were uniformly implanted into 5 in. silicon wafers. The oxidations were performed in a rapid thermal oxidation system by using dry O2 at a temperature of about 1000°C and for times up to 5 min. Transmission electron microscopy on cross sectional samples revealed that high quality buried oxide layers were formed and defect free single crystal silicon remained at the surface.© 1995 American Institute of Physics.