Novel LSI/SOI wafer fabrication using device layer transfer technique

A device layer transfer technique, wherein a device layer already fabricated on a silicon wafer is transferred onto an insulating substrate, has been developed for achieving an LSI/SOI wafer. This technique is based on preferential polishing, newly developed with a more than 100 Si/SiO2polishing rate ratio. A bipolar LSI active layer, formed in a 1 µm thick epitaxial layer, has been successfully transferred to a 4 inch diameter quartz glass. No change in IC-VCEcharacteristics of the transistor and leakage current of CB junction were observed. Isolation breakdown voltage was markedly improved after transfer. The device transfer technique is a promising method for realizing an LSI/SOI wafer with both large diameter and high crystal quality.