Silicon-on-insulator technology has attracted more attention than ever before because of its numerous unique features which are suitable to proliferating multimedia applications. In terms of its low-capacitance structure, SOI devices are seemingly identical to SOS devices. However, SOI devices differ from SOS counterparts in their high quality of material, various advantages ranging from low-power but high-speed operation, soft-error hardness, easy isolation, to capability to build 3D circuits and so on. SOI substrates can be obtained by thinning one of the two wafers down to a few microns or below. Crystal quality of SOI material was inferior to what is available, so that the application of SOI devices was limited to certain specialized areas such as radiation-hardened equipment. Considering the trend in the 90’s toward personalized multimedia computer systems, SOI technology is very attractive from viewpoints of low power consumption, high-speed operation, and low cost.