Schottky Source/Drain SOI MOSFET with Shallow Doped Extension

Abstract

Silicon-on-insulator metal-oxide-semiconductor field-effect-transistor (SOI MOSFET) whose source and drain are composed of deep Schottky contact and shallow-doped extension is investigated. This new structure aims at reducing the floating body effect of a partially depleted SOI MOSFET while keeping its current drive at the same level as that of the conventional pn junction SOI MOSFET. The shallow doping was performed by implanting Sb to form n-channel devices. Incorporation of the shallow extensions into the Schottky source and drain SOI MOSFET can increase the current drive by about 2 orders of magnitude owing to the reduction of the effective Schottky barrier. It can also decrease the leakage current owing to the reduced field at the drain Schottky contact. The effect of the new source and drain structure on the floating body effect is investigated by fabricating devices with body contact. The body current in MOSFET operation and tests in lateral bipolar operation show that the proposed source/drain structure is effective in reducing the floating body effect and therefore suppressing the early drain breakdown of the SOI MOSFET.