Ultra-thin-film SOI technology and its application to next generation CMOS devices

Although silicon-on-insulator (SOI) technology has been developed for over a quarter of a century, it has been in use only in specialized niche applications such as space and defense electronics systems. This is mainly because SOI manufacturing yields have been considered to be lower than their conventional bulk counterparts. In spite of the recent development of fully depleted SOI devices fabricated in ultra-thin silicon on insulator films which are considered very attractive for high-speed submicron ULSI applications because of the reduced short-channel effect in addition to the generic SOI advantages of latchup immunity and reduced parasitic capacitances, several problems which should be overcome still remain, both in materials and device technology as well as in manufacturing aspects,before thin-film SOI can be considered mainstream. The major potential application for ultra-thin SOI films is quarter micron CMOS devices for advanced logic circuits. It is anticipated that CMOS devices having design rules of 0.25 /spl mu/m or less will be in mass production by the end of this century, and conventional bulk silicon seems to be unsuitable for such ULSI devices mainly because of severe short channel effects. Instead, thin-film SOI with fully depleted silicon films is expected to be an alternative. >