Patent ID: 8659077

Claim:
A field-effect transistor (FET) replacement gate apparatus, comprising: a channel structure including a base and side walls defining a trench; a high-dielectric constant (high-k) layer formed on the base and side walls of the trench and having an upper surface conforming to a shape of the trench; a first layer formed on the high-k layer and conforming to the shape of the trench, the first layer comprising an aluminum-free metal nitride; a second layer formed on the first layer and conforming to the shape of the trench, the second layer comprising aluminum and at least one other metal, a ratio of aluminum to the at least one other metal is a gradient having a higher ratio at a center portion of the second layer and a lower ratio at ends of the second layer; and a third layer formed on the second layer and conforming to the shape of the trench, the third layer comprising an aluminum-free metal nitride.