FinFET gate structure and method for fabricating the same

A semiconductor device, comprising:

• a semiconductor substrate;
• a semiconductor fin on the semiconductor substrate;
• and
• a gate structure over the semiconductor fin, the gate structure comprising:
• a high-k dielectric layer;
• a metal layer over the high-k dielectric layer, wherein an atomic concentration of a metal within a first region of the metal layer is different than an atomic concentration of the metal within a second region of the metal layer;
• a blocking metal layer over the metal layer;
• and
• a first metal filler peripherally enclosed by the blocking metal layer.

A semiconductor device, comprising:

• a n-type gate structure;
• and
• a p-type gate structure, wherein each of the n-type gate structure and the p-type gate structure comprise:
• a high-k dielectric layer;
• a first TiN layer over the high-k dielectric layer;
• a TaN layer over the first TiN layer;
• a second TiN layer over the TaN layer;
• and
• a TiAl layer over the second TiN layer, wherein an atomic concentration of a metal within a first region of the TiAl layer is different than an atomic concentration of the metal within a second region of the TiAl layer.