US Patent 7338898 MOS transistor and fabrication thereof

A method for fabricating a MOS transistor is described. A gate dielectric layer, a first barrier layer, an interlayer, a work-function-dominating layer, a second barrier layer and a poly-Si layer are sequentially formed on a substrate. The interlayer is capable of adjusting the work function of the work-function-dominating layer and wetting the surface of the first barrier layer. The above layers are then patterned into a gate, and a source/drain is formed in the substrate beside the gate.