Methods for fabricating spatial light modulators with hidden comb actuators

Abstract

Described are methods for fabricating Micro-Electro-Mechanical Systems (MEMS) actuators with hidden combs and hinges. The ability to hide the combs renders the actuators useful in digital micro-mirror devices. Comb actuators provide increased torque, which facilitates the use of stiffer, less fragile hinge structures. Also important, comb actuators do not require mechanical stops to define stable states, and thus avoid problems associated with physical contact. The actuators are infinitely variable through a range of angles.

1 . A method of forming a comb actuator, the method comprising:
 a. depositing a first conductive layer;   b. patterning the first conductive layer to define a first comb;   c. depositing a first sacrificial layer over the first comb;   d. planarizing the first sacrificial layer to expose the first comb;   e. depositing a second conductive layer over the exposed first comb;   f. forming a mask on the second conductive layer, the mask defining a second comb; and   g. etching the second conductive layer through the mask to form the second comb.