ALD tungsten NEMS switches and tunneling devices

In this paper we present a novel low-temperature, CMOS compatible, top-down nanofabrication process employing ALD tungsten (WALD) as a structural material for nano-electro-mechanical systems (NEMS). Using this process, doubly-clamped suspended NEMS switches/tunneling devices have been successfully fabricated and demonstrated. The devices have been observed to perform comparably to two-terminal electrostatic carbon nanotube (CNT) switches, graphene-based switches, and MEMS tunneling devices. A lifetime of ∼50,000 cycles has been observed when these devices are operated in full contact switching mode, and a lifetime in excess of 5 × 106 cycles has been observed under low-current-limited operating conditions. In the tunneling regime a work function of 0.0682 eV has been calculated using experimental data coupled with finite element model (FEM) approximations. Under low-current-limited conditions the device behavior is stable and reproducible, resembling that of MEMS tunneling devices.