| 摘要 |
PROBLEM TO BE SOLVED: To prevent dopant atoms from migrating during a post gate conductor heat cycle by forming a gate electrode from a stack of doped polysilicon layer, tungsten nitride dopant barrier layer and tungsten silicide layer. SOLUTION: A MOSFET gate stack 27 is composed of a silicon dioxide gate oxide film 18, doped polysilicon control 20, tungsten nitride layer 22, tungsten silicide layer 24 and silicon nitride cap layer 26 in an insulation process. In the polysilicon-WSiX structure, an adequate dopant diffusion barrier is formed to suppress the dopant from outwards diffusing min. in the WSiX from the polysilicon layer. The diffusion barrier prevents the dopant from depleting in the polysilicon during a post-WSiX deposition annealing, the equivalent oxide thickness from increasing and associated MOSFET characteristics from deteriorating. |
