Monolithic arrays of micromachined pixels for infrared applications

Abstract

Small micromachined structures (typically 10/sup -5/ cm/sup 2/) have been fabricated with very small thermal mass (C) of about 10/sup -9/ J/K, which are suspended from the underlying silicon substrate by supports of such delicacy that the structures are extremely well thermally isolated from the substrate having a thermal conductance to the substrate of about 10/sup -7/ W/K. This thermal conductance (G) is close to the smallest value possible, about 10/sup -8/ W/K, due to radiative energy exchange. This high thermal isolation allows the microstructure temperature to be readily controlled by very small heating currents, or very small amounts of infrared (IR) incident flux. Large arrays of such microstructures have been fabricated on silicon wafers, with complex integrated electronic circuits, and operated as (1) sensitive room-temperature IR sensors ("microbolometers") and (2) large arrays of individually controllable IR microemitters.