Design and experiments for tunable optical sensor fabrication using (111)-oriented silicon micromachining

Abstract The paper presents the design and the experiments performed for integration of a micromechanical voltage tunable Fabry–Perot interferometer structure with a silicon p–n photodiode in order to obtain a tunable optical sensor. The Fabry–Perot interferometer can be used as a voltage tunable filter for the input radiation or as a voltage controlled attenuator to regulate the light from a monochromatic source. In our approach, the top mirror of the Fabry–Perot cavity is an Au/SiO 2 movable membrane, formed by anisotropic etching of (1 1 1)-oriented Si wafers. The Au layer provides a good reflectivity of the upper mirror. The air–silicon surface acts as the lower mirror, as the anisotropic etching of (1 1 1)-oriented Si wafers provides very smooth surfaces. The upper movable mirror can be electrostatically actuated. This Fabry–Perot interferometer was realized on the top of a p–n photodiode.

[1]  Bruce C. S. Chou,et al.  Micromachining on (111)-oriented silicon , 1999 .

[2]  W. Tsai,et al.  A novel structure for the intrinsic Fabry-Perot fiber-optic temperature sensor , 2001 .

[3]  E. Mozdy,et al.  Surface micromachined Fabry-Perot tunable filter , 1996, IEEE Photonics Technology Letters.

[4]  Dana Cristea,et al.  Experiments for microphotonic components fabrication using Si 〈1 1 1〉 etching techniques , 2002 .

[5]  D. Abeysinghe,et al.  A novel MEMS pressure sensor fabricated on an optical fiber , 2001, IEEE Photonics Technology Letters.

[6]  Gerhard Lammel,et al.  Free-standing, mobile 3D porous silicon microstructures , 2000 .

[7]  Tae Song Kim,et al.  Performance of Fabry–Perot microcavity structures with corrugated diaphragms , 2000 .

[8]  M. Gretillat,et al.  Reflective duplexer based on silicon micromechanics for fiber-optic communication , 1999 .

[9]  Carles Cané,et al.  A surface micromachining process for the development of a medium-infrared tuneable Fabry–Perot interferometer , 2004 .

[10]  Flat free-standing silicon diaphragms using silicon-on-insulator wafers , 2000 .

[11]  Mingzheng Jiang,et al.  A simple strain sensor using a thin film as a low-finesse fiber-optic Fabry–Perot interferometer , 2001 .

[12]  Dong-il Dan Cho,et al.  A New Micromachining Technique with (111) Silicon , 1999 .

[13]  Anders Hanneborg,et al.  Etch rates of (100), (111) and (110) single-crystal silicon in TMAH measured in situ by laser reflectance interferometry , 2000 .

[14]  O. Parriaux,et al.  Micromachining of high-contrast optical waveguides in [111] silicon wafers , 2000, IEEE Photonics Technology Letters.

[15]  Sadao Adachi,et al.  Optical Constants of Crystalline and Amorphous Semiconductors , 1999 .