A Novel Approach for Integration of Dual Metal Gate Process Using Ultra Thin Aluminum Nitride Buffer Layer

Abstract

We report and demonstrate a novel approach for dual metal gate CMOS process integration using an ultra thin aluminum nitride (AlNX) buffer layer between metal gate and gate dielectric. The buffer layer prevents the gate oxide from being exposed to a metal etching process and plays a key role in determining the work functions at the metal/dielectric interface. During annealing, this buffer layer is completely consumed through the reaction with metal gate and converted into a new metal alloy, resulting in no increase of EOT. The work functions of the original gate metals are modified as a result of this reaction, making this approach extremely attractive for dual metal gate CMOS applications.