A novel design and fabrication method of a pyramidal shape chip for scanning micro mirror

In this paper, we present a novel scheme for designing and fabricating a base chip, which is an approximation of a pyramid shape, and is not limited by the natural slope of 54.7° obtained with wet anisotropic etching of silicon. The application for such a pyramid shape, in our case, is for a single axis scanning micro mirror. The paper presents the methodology for designing and fabricating a surface with an arbitrary slope, as required by the application. In our case, it is an approximation of a desired very moderate slope. The moderate slope serves as an electrostatic actuator with relatively low operating voltage. On top of the base, we bond a mirror chip that includes the opposite side of the actuator, the reflector of the mirror, the mechanical structure of the mirror and the hinges. We present in this paper the motivation to use a pyramidal shaped base. The design is simple and requires knowledge of etch rates in several crystal planes, which can be easily measured. The fabrication tools and methods used herein are based on wet etching of silicon wafers. There is no need for DRIE processes or SOI wafers.