Method for preventing dopant diffusion in dual gate device

摘要

A method for preventing the diffusion of dopants in a dual gate device includes the steps of providing a semiconductor substrate having wells and isolating structures thereon, and then forming a gate oxide layer over the well regions. Thereafter a polysilicon layer is formed over the gate oxide layer, and then a first conductive layer is formed over the polysilicon layer. Subsequently, a plasma treatment using gaseous nitrogen or gaseous ammonia is conducted to form a barrier layer. Finally, a second conductive layer is formed over the barrier layer.