The performance and reliability of NMOSFET asymmetric lightly doped drain (LDD) devices (with no LDD on the source side) are compared with those of conventional LDD devices. At a fixed Vdd, asymmetric LDD devices exhibit higher Idsat and shorter hot-carrier lifetime. To maintain the same hot-carrier lifetime, asymmetric LDD devices must operate at lower Vdd while higher Idsat is retained. For the same hot-carrier lifetime, ring oscillators with NMOSFET asymmetric LDD devices can achieve 5% (10% if PMOSFET also had asymmetric LDD) higher speed and 10% lower power. The hot-carrier reliability of inverter, NAND, and NOR structures with asymmetric and conventional LDD devices is also simulated and compared.
- Hot carriers
- Integrated circuit reliability
- Semiconductor device reliability