45nm high-k + metal gate strain-enhanced CMOS transistors

At the 45 nm technology node, high-k + metal gate transistors were introduced for the first time on a high-volume manufacturing process [1]. The introduction of a high-k gate dielectric enabled transistors with a 0.7x reduction in Tox (electrical gate oxide thickness) while reducing gate leakage 1000x for the PMOS and 25x for the NMOS transistors. Dual-band edge workfunction metal gates were introduced, eliminating polysilicon gate depletion and providing compatibility with the high-k gate dielectric. High-k + Metal gates have also been shown to have improved variability at the 45 nm node [2]. In addition to the high-k + metal gate, the 35 nm gate length CMOS transistors have been integrated with a third generation of strained silicon and have demonstrated the highest drive currents to date for both NMOS and PMOS. An SRAM cell size of 0.346 mum
²
has been achieved while using 193 nm dry lithography. High yield and reliability has been demonstrated on multiple single, dual-, quad- and six-core microprocessors.