Abstract
In this thesis, four types of devices are fabricated:NMOS and PMOS with 4-nm gate-oxide grown in either O2 or NO2 atmosphere. Gate leakage current, threshold voltage shift, mobility degradation, oxidetrapped charge(Qot) and interface-trapped charge (Qit) generated after different electrical stresses are studied. Both Qot and Qit cause stress-induced threshold voltage shift and mobility degradation. For 4nm gate-oxide MOSFETs, the generated Dit after VG<0 Fowler-Nordheim stress of a IG=80mA/cm2 at 50 sec is 1.3×1011cm-2 .The generated Qot is 2.5×1010cm-2 .Qit is therefore more dominant than Qot for the both issues by. The generation of Qit by different stresses is studied. It is conchuded that the energy released in the impact ionization event is one of the primary reasons for interface-trap generation by VG<0 FN stress. Hot holes impacting the interface is another. The stress-induced Qit of gate-oxides grown with N2O and O2 are compared in this work. N2O-grown gate-oxide has better hole-injection prevention than O2-grown oxide. For PMOS, hot holes generate less interface traps at N2O-grown gate-oxide. Beside, N2O-grown gate-oxide has good boron-penetration prevention and better polysilicon depletion prevention.In the future, N2O-grown gate-oxide will be the trend for VLSI gate-oxide process.