Polycrystalline silicon/metal stacked gate for threshold voltage control in metal–oxide–semiconductor field-effect transistors

A stack structure for the gate electrode of metal–oxide–semiconductor (MOS) transistors is proposed, analyzed, and simulated. The stack consists of a very thin polycrystalline silicon (polysilicon) layer and metal. By changing the thickness of the polysilicon layer, one can change the effective work function of the gate. Thus, the stacked-gate structure allows for a method to continuously adjust MOS field-effect transistor threshold voltage through gate work-function engineering while retaining the proven SiO₂/polysilicon interface. © 2000 American Institute of Physics.