Bias-temperature instability on fully silicided-germanided gates/high-k Al2O3CMOSFETs

Abstract

We have studied bias-temperature instability (BTI) on fully nickel-silicided (NiSi) and germanided (NiGe) gates on high-k Al2O3 n metal oxide semiconductor field effect transistors (MOSFETs) and pMOSFETs, respectively. At an equivalent oxide thickness of 1.7 nm, the NiSi/Al2O3 pMOSFETs and NiGe/Al2O3 nMOSFETs have a comparable threshold voltage (V-t) change of -34 and 33 mV at 85° C and 10 MV/cm stress for 1 h. This result is different from the more severe negative BTI (NBTI) degradation measured in oxynitride pMOSFET than positive BTI (PBTI) in nMOSFET. The extrapolated maximum voltage for 10 years' lifetime is 1.16 and -1.12 V from NiSi-NiGe/Al2O3 complementary MOSFETs (CMOSFETs) that can barely meet the required 1 V operation with 10% safety margin. Further improvement is still required because the 1.8 nm oxynitride CMOSFETs have higher 10 years' lifetime operation voltages of 2.48 and -1.52 V for PBTI and NBTI, respectively. © 2005 The Electrochemical Society. All rights reserved.