Reducing Dynamism in DRAM With Bistable MEMS Switch as Sleep Transistor

Abstract

We demonstrate the bistable microelectromechanical system (MEMS) sleep-transistor for CMOS integrated circuits (ICs). The sleep transistor has infinite sleep mode resistance and ~2.5-Ω resistance in active mode. The hold bias in active mode is zero for the bistable MEMS sleep transistor. The proposed bistable MEMS switch is an ideal candidate for gating the power-hungry digital circuits. The dynamic random access memory (DRAM) supply rails gated with bistable MEMS sleep transistors offer ~6 order reduction in refresh rate. This article also reports on the design guidelines for the CMOS compatible fabrication of bistable MEMS sleep transistor. Only ~0.31 pJ of energy is consumed, in toggling between the modes of bistable MEMS sleep transistor. The MEMS gate can drive large area CMOS circuit blocks with fuse current density of ~0.5 mA/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Furthermore, the fabrication of the bistable MEMS sleep transistor is critical in the aspect that its design is a play between restoring and adhesion forces.