Substrate-bias effect and source-drain breakdown characteristics in body-tied short-channel SOI MOSFET´s

The substrate-bias effect and source-drain breakdown characteristics in body-tied short-channel silicon-on-insulator metal oxide semiconductor field effect transistors (SOI MOSFET´s) were investigated. Here, “substrate bias” is the body bias in the SOI MOSFET itself. It was found that the transistor body becomes fully depleted and the transistor is released from the substrate-bias effect, when the body is reverse-biased. Moreover, it was found that the source-drain breakdown voltage for reverse-bias is as high as that for zero-bias. This phenomenon was analyzed using a three-dimensional (3-D) device simulation considering the body-tied SOI MOSFET structure in which the body potential is fixed from the side of the transistor. This analysis revealed that holes which are generated in the transistor are effectively pulled out to the body electrode, and the body potential for reverse-bias remains lower than that for zero-bias, and therefore, the source-drain breakdown characteristics does not deteriorate for reverse-bias. Further, the influence of this effect upon circuit operation was investigated. The body-tied configuration of SOI devices is very effective in exploiting merits of SOI and in suppressing the floating body-effect, and is revealed to be one of the most promising candidates for random logic circuits such as gate arrays and application specific integrated circuits