A micro optical filter using polysilicon surface micromachining process

Abstract

Surface micromachining fabrication process offers a novel approach for realizing micro-optical system onto a chip. A new micromachined micro optical filter which relies on intensity changes due to the interaction between a light beam and the optical shutter has been designed, fabricated and tested. The micro optical filter consists of a 2 micron thick polysilicon shutter suspended from the substrate by springs which are 200 micron long polysilicon folded beams. The sacrificial layer which is sandwiched between the silicon substrate and the structure is removed with a hydrofluoric acid wet etch, and a selfassembled monolayer coating is used to prevent friction. The filter is designed as a mass-spring system that moves in response to acceleration force. An application of accelerometer with higher sensitivity in a lower acceleration range is expected.