Structure Design And Fabrication Of Micro F-P Cavity Tunable Filter

Micro F-P cavity tunable filter, one of the Micro-opto-electro-mechanical devices, has been widely applied in the area of hyperspectral imaging, DWDM optical communication and self-adaptive optics. The Micro F-P cavity tunable filter may be the selective optical filter device for the future Space Target Detection System, because of its superior speed, large spectral range, high definition and high contrast. With the development of the micro fabrication technology, the micro tunable filter array, the key element of hyperspectral imaging device, will be made and applied in the area of Space Target Detection System. Compared with traditional devices,such as electro-optical and acuosto-optical devices, micro tunable filter arrays help to realize the hyperspectral imaging with high frequency, small volume and simple structure.This paper presents the modeling, design and experimental research on 10×5 electrostatic-drived micro tunable filter arrays. The main contents are as follows:(1)The mechanism and structural characteristics of micro tunable filter are analyzed systematically. The dimensions are given by combining the structural design principles and process conditions. A micromaching process is put forward to fabricate the micro tunable filter and correspondent masks have been designed by LEDIT for the fabrication processes.(2)Finite element analysis software ANSYS is employed to simulate the electrical and mechanical characteristics of micro tunable filter, by which the static and dynamical characteriastics are analyzed, such as stress, modal, transient respondence, etc. The simulation results indicate the designing is reasonable.(3)The micro-fabrication processes are studied specifically, especially the cantilever and sacriface layer processes. Metal lift-off, PECVD SiO2 as dielectrics cantilever and reactive ion etching of SiO2 are presented for patterning cantilever. Furthermore, the characteristics of ZKPI are analyzed, and then, the desired pattern on sacrificial layer are achieved by UV photolithography technology which has been optimized. Eventually. The sacrificial layer with designed hight, flat surface, stable chemical and mechanical performance is acquired by adjusting multi-coating and post annealing. Additionally, the optimal conditions to release the sacrificial layer with O2 plasma is also presented in this article. (4)The Ni/Cr layer is achieved on the SiO2 etching resistance layer by Ion Beam Sputtering, to form electricity interconnection.