Technique for forming electric field shielding layer in oxygen-implanted silicon substrate

Abstract

A process for forming an electric field shielding layer in a SIMOX substrate entails carrying out a high beam-current oxygen implant over a manufacturing-acceptable period of time, which increases the wafer temperature (on the order of 500.degree. C.) causing in situ annealing of the substrate and suppresses the initial formation of an EFS layer. After the oxygen implant step and prior to subsequent annealing, however, the oxygen implanted silicon substrate is subjected to a medium dose silicon implantation (10.sup.15 -10.sup.16 Si.sup.+ cm.sup.-2) with projected ion range near the interface of the silicon-on-insulator film and the buried oxide layer. This high-throughput implantation can be carried out at or near room temperature in only several minutes and effectively creates an oxygen-doped amorphous silicon precursor EFS layer atop the buried dielectric layer, while leaving the overlying surface silicon layer relatively undamaged. Subsequent annealing of the dual oxygen/silicon-implanted substrate at a temperature on the order of 1,150.degree. C.-1,250.degree. C. then leads to the formation of an oxygen-doped polycrystalline EFS layer atop the buried dielectric silicon dioxide layer and separated from the top device-quality crystalline silicon film by a thin interfacial oxide layer. Thus, this technique results in a high-volume front-end microelectronics process for producing SIMOX wafers that incorporate an EFS layer tailored by an intermediate self-implant amorphization step.

Dependencies are inferred from the claim text.