Methods of fabricating in-plane mems thermal actuators

Abstract

A MEMS thermal actuator device is provided that is capable of providing linear displacement in a plane generally parallel to the surface of a substrate. Additionally, the MEMS thermal actuator of the present invention may provide for a self-contained heating mechanism that allows for the thermal actuator to be actuated using lower power consumption and lower operating temperatures. The MEMS thermal actuator includes a microelectronic substrate having a first surface and at least one anchor structure affixed to the first surface. A composite beam extends from the anchor(s) and overlies the first surface of the substrate. The composite beam is adapted for thermal actuation, such that it will controllably deflect along a predetermined path that extends substantially parallel to the first surface of the microelectronic substrate. In one embodiment the composite beam comprises two or layers having materials that have correspondingly different thermal coefficients of expansion. As such, the layers will respond differently when thermal energy is supplied to the composite. An electrically conductive path may extend throughout the composite beam to effectuate thermal actuation. In one embodiment of the invention a two layer composite beam comprises a first layer of a semiconductor material and a second layer of a metallic material. The semiconductor material may be selectively doped during fabrication so as to create a self-contained heating mechanism within the composite beam. The invention also comprises a MEMS thermal actuator that includes two or more composite beams. The two or more composite beams may be disposed in an array or a ganged fashion, such that the multiple composite beams benefit from overall force multiplication and are therefore capable of greater and more linear displacement distances. The invention is also embodied in a method for fabricating the MEMS thermal actuators of the present invention.