Fabrication and characterization of IC-Compatible Linear Variable Optical Filters with application in a micro-spectrometer

This paper reports on an IC-Compatible process for the fabrication of Linear Variable Optical Filter (LVOF). The LVOF is integrated with a detector array to result in a micro-spectrometer. The technological challenge in fabrication of an LVOF is fabrication of a well-controlled tapered cavity layer. Very small taper angles, ranging from 0.001 degrees to 0.1 degrees. are fabricated in a resist layer by just one lithography step and a subsequent reflow process. The 3D pattern of resist structures is subsequently transferred into SiO(2) by an appropriate etching. Complete LVOF fabrication involves CMOS-compatible deposition of a lower dielectric mirror using a stack of dielectrics on the wafer, tapered layer formation and the deposition of the top dielectric mirror. The design principle, IC-Compatible processing and the characterization results on fabricated LVOFs are presented. (C) 2010 Elsevier B.V. All rights reserved.