US Patent 7723176 Method for manufacturing semiconductor device

Element characteristics disadvantageously fluctuate because the composition of the resultant silicide varies according to the change of the gate length when a full silicide gate electrode is formed by sintering a metal/poly-Si structure. The element characteristics also fluctuate due to element-to-element non-uniformity of the resultant silicide composition. By first forming full silicide having a metal-rich composition, depositing a Si layer thereon, and sintering the combined structure, the metal in the metal-rich silicide diffuses into the Si layer, so that the Si layer is converted into silicide. The entire structure thus is converted into full silicide having a smaller metal composition ratio.