Process for in-plane and out-of-plane single-crystal-silicon thermal microactuators

A process to manufacture single-crystal thermal actuators using silicon fusion bonding and electrochemical etch stop is presented. The process permits the simultaneous creation of in-plane and out-of-plane thermal actuators together with levers suitable for both directions of actuation. A final dry-release step is used, permitting the manufacture of MOS or bipolar devices in conjunction with actuators. Out-of-plane actuation of vertically levered devices has been demonstrated. The −3 dB response frequency of out-of-plane actuators is approximately 1000 Hz in air. Novel levered in-plane devices which achieve deflections of up to 200 μm have been fabricated. An estimate of the upper bound of thermal actuator efficiency is presented.