ELECTRON-MOBILITY IN ULSI MOSFETS - EFFECT OF INTERFACE TRAPS AND OXIDE NITRIDATION

We provide a comprehensive set of electron mobility measurements at 30 0 K and 77 K on standard and NaO-nitrided MOSFET's, with channel dopin g in the range 3.8 x 10(17)-1.25 x 10(18) cm(-3), In such heavily-dope d devices, the Fermi level always lies very close to the conduction ba nd edge, where interface traps reach the highest density and the short est lifetimes, We show that these traps contribute to the gate-channel capacitance, leading to a systematic overestimate of the channel char ge, This effect has the largest impact precisely in the roll-off regio n of the mobility curves, which has been the subject of recent theoret ical investigations.