Single-contact, four-terminal microelectromechanical relay for efficient digital logic

Nano and microelectromechanical relays can be used in lieu of transistors to build digital integrated circuits that can operate with zero leakage current at high operating temperatures and radiation levels. Four-terminal (4-T) relays facilitate efficient logic circuits with greatly reduced device counts compared to three-terminal (3-T) relay implementations. Existing 4-T relays, however, require two moving contacts to simultaneously land on two stationary electrodes, which can adversely impact reliability, or have complex out-of-plane fabrication methods that can reduce yield and increase cost while having poor scalability. In this work an in-plane four-terminal relay with a single moving contact is demonstrated for the first time, through successful fabrication and characterization of prototypes with a critical dimension of 1.5 µm. Body biasing is shown to reduce the pull-in voltage of this 4-T relay compared to a 3-T relay with the same architecture and footprint. The potential of the 4-T relay to build efficient logic circuits is demonstrated by fabricating and characterizing a 1-to-2 demultiplexer (DEMUX) circuit using only two devices, a saving of eight devices over a 3-T relay implementation