Impact on 1/f Noise due to Gate Electrodes in High-k. Based MOSFETs - A Comparison Study Between Poly-Si Vs Metal Vs FUSI

Abstract

This work summarizes the effects of using three different gate electrodes -poly-Si, fully silicided (FUSI) and metal (TiN-TaN) on drain current low-frequency (1/f) noise in devices with HfO 2 as gate dielectric oxide. While 1/f β type spectra were observed, the frequency exponent β was found to vary. Number fluctuations were found to be the dominant mechanism for 1/f noise. 1/f noise in poly-Si based oxides show the highest noise while FUSI based devices show the lowest noise. A specific behavior was observed in SiO 2 and HfO 2 regions of oxide, when the trap profiles are assessed using f x S Vg spectra. Constant, decreasing and increasing trap distribution profiles were observed in the HfO 2 region for poly-Si, FUSI and metal gate electrodes respectively. Investigations reveal that the oxygen transport during the gate electrode processing were mainly responsible for the observed differences in 1/f noise.