MOBILITY IMPROVEMENT OF N-MOSFETS WITH NITRIDED GATE OXIDE BY BACKSURFACE AR+ BOMBARDMENT

Low-energy (550 eV) argon-ion beam was used to bombard directly, the b acksurface of nitrided n-MOSFET's after the completion of all conventi onal nMOS processing steps. The interface characteristics and inversio n layer mobility of the MOS devices were investigated. The results sho w that, as bombardment time increases, interface state density and fix ed charge density decrease first, and then the change slows down or ev en turns around. Correspondingly, the carrier mobility iind drain cond uctance of the MOS devices are found to enhance first, and then satura te or turn around, Therefore, this simple technique, which is readily compatible with existing IC processing, is effective for restoring som e of the lost device performance associated with gate-oxide nitridatio n.