On the electro-mechanical reliability of NEMFET as an analog/digital switch

Abstract

In this article, we identify and evaluate the major reliability issues (Negative Bias Temperature Instability, Hot Carrier Injection, and Creep) of Nano-Electro-Mechanical Field Effect Transistor (NEMFET) when used as an analog or digital switch. We use Euler-Bernoulli equation to model the static and dynamic behavior of NEMFET and couple it with classical theories of NBTI, HCI and creep to predict the associated lifetime of the device. Since NBTI and HCI are regularly observed in classical Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET), we compare NBTI and HCI induced degradation in NEMFET with that of a MOSFET. We find that, NBTI time-evolution in NEMFET is comparable to that of a MOSFET. In spite of this similarity, while NBTI causes only parametric degradation in MOSFET, it changes the pull-in/pull-out voltage of NEMFET that could lead to catastrophic failure due to stiction. Next, we study HCI, which is a persistent reliability concern for MOSFET, and find that NEMFET may be immune to HCI degradation due to NEMFET's intrinsic pull-in and release dynamics. Finally, we study time dependent mechanical creep in NEMFET for below pull-in operation and find that a time dependent increase in the off-state capacitance and power consumption may negate one of the major advantages of NEMFET as a replacement for MOSFET.