High performance bulk MOSFET fabricated on SOI substrate for ESD protection and circuit applications

With the rapid advancement of SOI technology, SOI device and circuit performances keep steadily improving. However, some fundamental problems such as self-heating and ESD are still un-resolved. Such adverse effects can be easily dealt with by combining bulk technologies with current SOI technologies on the same wafer. It has been shown that NMOS buffers built on the substrate of SOI wafers can provide significant improvement in ESD protection for SOI circuits. Also, the availability both SOI and bulk technologies can facilitate the design of high performance circuits. Integration of SOI and bulk technologies can easily be done after selectively etching of the silicon film and buried oxide. However, due to the difference in surface quality, the performance of these substrate MOSFETs is not very clear. Issues such as electron mobility, gate oxide quality and hot carrier reliability have to be addressed. In this paper, the performance of substrate MOSFETs fabricated on SIMOX wafers are evaluated and compared with normal bulk wafers fabricated in the same process lot.