1.5-V single work-function W/WN/n/sup +/-poly gate CMOS device design with 110-nm buried-channel PMOS for 90-nm vertical-cell DRAM

This letter reports on 1.5-V single work-function W/WN/n/sup +/-poly gate CMOS transistors for high-performance stand-alone dynamic random access memory (DRAM) and low-cost low-leakage embedded DRAM applications. At V/sub dd/ Of 1.5-V and 25/spl deg/C, drive currents of 634 /spl mu/A//spl mu/m for 90-nm L/sub gate/ NMOS and 208 /spl mu/A-/spl mu/m for 110-nm L/sub gate/ buried-channel PMOS are achieved at 25 pA//spl mu/m off-state leakage. Device performance of this single work function technology is comparable to published low leakage 1.5-V dual work-function technologies and 25% better than previously reported 1.8-V single work-function technology. Data illustrating hot-carrier immunity of these devices under high electric fields is also presented. Scalability of single work-function CMOS device design for the 90-nm DRAM generation is demonstrated.