A VFB tunable Single Metal Single Dielectric approach using As I/I into TiN/HfO2 for 32nm node and beyond

Abstract

Easily integrable cost effective gate first Single Metal Single Dielectric (SMSD) solution based on As implantation into TiN/HfO2 with ∼ 1 nm EOT is presented. A consistent n-type shift of 250 mV down to 35 nm Lg is obtained by As I/I compared to the reference stack. Symmetrical threshold voltages (∼ ±0.5 V) are met for the bulk planar devices using this technique, which would corresponds to low-VT (±0.2V) target for the FD FETs. The possible counter-doping effects were evaluated electrically and physically with backside SIMS. It was found to be negligible implying negligible concentration of As in the channel region. As I/I technique opens up possibility of multiple VT tuning without adding any process complexity.