Single-device “XOR” and “AND” gates for high speed, very low power LSI mechanical processors

Abstract

Here we demonstrate the feasibility of micro-electro-mechanical system (MEMS) functional devices where a single device functions as a logic gate. This novel approach reduces the number of MEMS devices needed to implement a mechanical processor by a factor of 10. MEMS processors are suitable for operation in harsh environment in engines and in the presence of ionizing radiations inside nuclear reactors or in space applications. MEMS devices have overall lower speed and are less reliable than the complementary metal-oxide-semiconductor (CMOS) devices. By reducing the number of devices needed for a given operation, our approach improves yield, reproducibility, speed and simplifies implementation of MEMS circuits such as adders and multiplexers. Specifically, we discuss XOR and AND gates fabricated on Si3N4 and polysilicon as bridge materials using W electrodes. The XOR gates with ∼1.5V turn-on voltage at 50MHz with >109 cycles of reliable operations and low operational power consumption (leakage current <10−9A at V∼0.5V, and power <1μW) were tested. We also present data showing the operation of XOR without deterioration at high temperature and in 90kW ionizing radiation for 120min. Related circuits such as a 2-bit full adder and a multiplexer are also discussed.