0.35-MU-M ASYMMETRIC AND SYMMETRICAL LDD DEVICE COMPARISON USING A RELIABILITY SPEED/POWER METHODOLOGY/

The reliability and performance of NMOSFET asymmetric LDD devices (wit h no LDD on the source side) are compared with that of conventional LD D devices. The results show that asymmetric LDD devices exhibit higher I-dsat and larger I-sub. To maintain the same hot-carrier lifetime, a symmetric LDD devices must operate at lower V-dd. For the same hot-car rier lifetime, we show that ring oscillators with asymmetric LDD devic es can achieve 5% (10% if PMOSFET also had asymmetric LDD) higher spee d and 10% lower power.