Buried oxide formation by plasma immersion ion implantation

Although separation by implantation of oxygen (SIMOX) is an attractive approach for fabricating silicon-on-insulator (SOI) materials for radiation-hardened electronic devices and high-speed CMOS circuits, the production cost is high. The novel technique of plasma immersion ion implantation (PIII) emulates the traditional beamline technique in many aspects. Some of the advantages are: no mass selection, no beam transport optics, large area implantation, high ion flux, short implantation time, and low costs. We used PIII and oxygen implantation (nominal dose: 5 × 10¹⁷ atoms/cm²) to form thin buried oxide layers in the sub-mtorr operating pressure regime. A 20-50 nm thick buried oxide layer with a Si overlayer thickness of 20-50 nm was fabricated in about 5 min. The implanted wafers were capped with a nitride layer and subsequently annealed for 6 h at 1300 °C in a nitrogen ambient to remove the damage. The resulting wafers were analyzed using a variety of techniques, including RBS and XTEM.