Improvement of Aluminum Diffusion in HKMG Process

Excess aluminum diffusion is always the main concern in the high-k metal gate (HKMG) process at 28/22nm node. In this work, we try to add extra ALD TaN film before TiAl and Al eletrode and the thickness of bilayer TaN, SIMS analysis, Vt variation, fail bin and the mechanism was well studied in this paper. Experiment result show excess Al was well suppressed with extra TaN added before TiAl. CP bin Trans_AVS and Vmin_HPM performance was significantly improved. A good performance was achieved finally.