| 摘要 |
A method for forming a gate of a semiconductor device is provided to reduce gate depletion and to control an out-diffusion of p-type impurity from a poly silicon layer to a metal layer by forming a silicon layer where the n-type impurity is ion-implanted on the metal layer of a PMOS forming region as a diffusion preventing layer. A semiconductor(200) where a P-well(202a) and an N-well(202b) are formed is provided. A gate dielectric(210) is formed on the semiconductor substrate. A non-doped poly silicon layer is formed on the gate dielectric. N-type impurities are selectively ion-implanted into the non-doped poly silicon layer part formed on the P-well. P-type impurities are selectively ion-implanted into the non-doped poly silicon layer part formed on the N-well. A metal layer(230) and a silicon layer(235) are formed in turn on the resultant structure. N-type impurity is selectively ion-implanted into the silicon layer part formed on the N-well. The silicon layer, the metal layer, the poly silicon layer, and the gate dielectric are etched in turn.
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