Fabrication of smooth 45° micromirror using TMAH low concentration solution with NCW-601A surfactant on <100> silicon

Yi Wei Xu; Aron Michael; Chee Yee Kwok

doi:10.1117/12.759343

9 January 2008 Fabrication of smooth 45° micromirror using TMAH low concentration solution with NCW-601A surfactant on <100> silicon

Yi Wei Xu, Aron Michael, Chee Yee Kwok

Author Affiliations +

Proceedings Volume 6800, Device and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV; 68001W (2008) https://doi.org/10.1117/12.759343
Event: SPIE Microelectronics, MEMS, and Nanotechnology, 2007, Canberra, ACT, Australia

Abstract

Paper reports improved results in the fabrication of 45° micromirrors using low concentration of TMAH with NCW-601A surfactant. 45° micro mirror is an essential component for obtaining 90° out-of-plane reflection of the optical beam. TMAH anisotropic wet etching on (100) silicon wafer with features aligned to the flat so that 45° slope is formed on (110) plane. This requires the etch rate of <110> planes to be lower than <100> planes. Etching rate selectivity depends on: temperature, concentration, and additives. Substantial undercutting of mask needs to be taken into consideration during the design. TMAH concentrations ranging from 2.5% to 10% with different concentrations of surfactant have been studied to achieve improved smoothness of the micromirror surface and better selectivity. SEM/AFM measurement show the roughness of mirror is less than 1nm. Results also show that the surface roughness varies along the 45° slope with the roughest portion at the top of the mirror. This paper will describe the techniques to reduce the size of the rough portion of the mirror.

Citation Download Citation

Yi Wei Xu, Aron Michael, and Chee Yee Kwok "Fabrication of smooth 45° micromirror using TMAH low concentration solution with NCW-601A surfactant on <100> silicon", Proc. SPIE 6800, Device and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV, 68001W (9 January 2008); https://doi.org/10.1117/12.759343

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