Large area molded silicon nitride micro mirrors

• Published in: IEEE photonics technology letters Vol. 15; no. 10; pp. 1407 - 1409
• Main Authors: Lutzenberger, B.J., Dickensheets, D.L., Kaiser, T.J.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2003; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Chemical vapor deposition; Construction; Deposition; Deviation; Etching; Fins; Micromirrors; Mirrors; Molds; Noise levels; Optical films; Optical switches; Optical switching; Semiconductor thin films; Silicon; Silicon nitride; Sputtering; Temperature distribution
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2003.818046

Large area molded torsional micromirrors have been fabricated from thin films of low-pressure chemical vapor deposition silicon nitride. Optical surfaces as large as 400 μm in diameter with surface deviations less than 0.33 μm have been fabricated from 1.5-μm-thick layers of silicon nitride. Surface flatness was achieved by molding latticed silicon nitride fins to the backside of the mirrors. Fins as deep as 28 μm were constructed by deep reactive ion etching bulk silicon to produce molds for the fins prior to silicon nitride deposition. Mirrors with fins were shown to be insensitive to temperature effects within the range of 50-120 /spl deg/C. An optical switch with insertion loss less than 2 dB was constructed with the mirrors, demonstrating their potential as switch elements in optical systems.