Method of making semiconductor-on-insulator device with closed-gate electrode

摘要

A body-tied MOSFET (14) is used in a protection circuit (10) of an SOI device (20) where the MOSFET's drain regions (38) lie outside MOSFET's closed-gate electrode (34). Electrical characteristics of the body-tied MOSFET (14) can be changed by varying the ratio of the total source region area to the total body-tied region area (tie frequency). The total electrical device width is the sum of the individual source region (36) widths. More charge can be placed on the drain region (38) compared to a drain region on the inside because the interfacial area between the drain region and channel region is larger. The device (20) can be formed without having to develop new processing steps or use marginal processing steps. Body ties to an underlying substrate are unnecessary.