Gate materials consideration for submicron CMOS

Abstract

The selection of the gate materials for submicron CMOS devices were discussed in respect to work function, resistivity and other properties. Dual polysilicon gates and single mid-gap metal gate are two viable approaches. The pros and cons for each approach are discussed. In general, the single mid-gap metal gate approach is simpler in process as compared with the dual polysilicon gate approach, and has better performance down to 0.5 μm CMOS regime due to its lower resistivity and the contribution to higher electron mobility. However, the selection of the new materials and the development of the new processes will not be simple. Sputtered tungsten was carefully studied and chosen as the mid-gap gate material. Submicron tungstn gate NMOSFET devices were fabricated, characterized and compared with the n+ polysilicon gate devices to reach to the conclusions. © 1989.