Low-Voltage SOI CMOS VLSI Devices and Circuits

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SOI CMOS Devices–Part I

Behaviors of SOI CMOS devices are quite different from those of the bulk ones. Understanding the unique behavior of the SOI CMOS devices is important for designing SOI CMOS VLSI circuits. In this chapter, fundamental SOI CMOS technology is described first, followed by the phenomena of SOI CMOS devices. The back gate bias effects of SOI CMOS devices are introduced. Then short and narrow channel effects are described, followed by mobility including the velocity overshoot phenomenon. Unique phenomena of SOI CMOS devices caused by their floating body structure may cause peculiar drain current characteristics–kink effects. In this chapter, floating body effects and subthreshold characteristics of SOI CMOS devices are analyzed. Also depicted are impact ionization, snapback, bipolar leakage, and bipolar history effects derived from the floating body structure. Because of the insulating buried oxide below the active thin-film region, SOI CMOS devices are susceptible to thermal effects–self-heating. In the final portion of this chapter, self-heating of SOI CMOS devices is presented, followed by the transient analysis of SOI CMOS devices.

2.1 BASIC SOI TECHNOLOGY

The fabrication process of SOI CMOS technology is similar to the bulk CMOS counterpart except for the starting silicon wafers. In this section, fundamental SOI CMOS technology in terms of SOI wafers and ...