The progress of microelectonics technology has chronically required aggressive developmenmts of materials as well as device processes. The requirements of silicon wafer as a very primary material have been changed quite predictable based on the device development progresses so far. However, the ruquirements of the next generation devices is heading to the limits of their functions and materials and aksing the very specific silicon wafer such ans SOI(Silicon On Insulator) wafer. The talk covers the domestic and world-wide status of SOI wafter technology development, several matured technology directions and their comparisons, and properties of SOI devices. The presentation also treats some predictions such as SOI developmet, schedules, impacts on the bulk wafer developments, market development and size, SOI wafer prices, and other applications of SOI technology. Fnally it covers technicla details which are silicon oxide conditions for bonding, point defects and their behaviours, surface contaminations, and so on. These points will be hopefully overcome by people who face to SOI or the related technology developments.