Alternative body contact for fully-depleted silicon-on-insulator

Abstract

Two preferred embodiments for an alternative body contact are disclosed for fully-depleted silicon-on-insulator transistors. In one preferred embodiment, body contact is made by extending the mesa ends of the body ties down to, and merging them with, mesa regions of an nFET source and using self-aligned silicide (commonly known as salicide) to make a connection to an underlying nFET well. In this first embodiment, the mesas of the body ties merge with the mesa of the source and salicide is used to short out these regions. In another preferred embodiment, body contact is made by extending the mesa ends of the body ties down to the nFET source; however, the mesas are not merged. In this second embodiment, metal routing, which is commonly used to electrically connect circuit elements, is extended to connect to the mesa regions of the body ties. In both embodiments, the body ties are active until the onset of full depletion; however, at the onset of full depletion, the body ties are electrically severed.