Limitation of WSix/WN Diffusion Barrier for Tungsten Dual Polymetal Gate Memory Devices

We compared WSix/WN and Ti/WN diffusion barriers for tungsten dual polymetal gate (W-DPG) application, in terms of device performance and gate oxide reliability. WSix/WN diffusion barrier shows degradation of gate oxide, which is found to be due to the B-N dielectric formation and subsequent breakdown of diffusion barrier. Relatively, Ti/WN diffusion barrier shows excellent device performance in terms of R/O delay and gate oxide reliability.