AVD and MOCVD TaCN-based Films for Gate Metal Applications on High k Gate Dielectrics

Abstract

Atomic Vapor Deposition (AVD®) and MOCVD of TaCN-based films are studied for high work function needed for PMOS Gate-first designs. Work functions as high as 4.85eV and 4.92eV are achieved on HfSiON and HfSiO high k dielectrics, respectively. The film composition was varied from pure Ta2N to TaC films which improve the work function as well as thermal stability. The high work function was different depending on whether different underlying high k dielectrics and N compositions were used. The approaches for obtaining high work function and the impact of underlying high k films are discussed. After detailing the physical and chemical characteristics of MOCVD and AVD® TaCN films, this paper correlates the deposition technologies to the high work function values obtained by extraction from flatband voltage / equivalent oxide thickness (EOT) measurements.