Fabrication and characterization of multilayer porous silicon filter considering the natural-drifts in Etch Rate

초록

We reported on the characterization and fabrication of multilayer porous silicon (PS) free-standing filter. The Fabry-Perot structures containing two distributed Bragg reflectors(DBR) with microcavity between them. The PS based Fabry-Perot interference filter were prepared by electrochemical anodic etching with p+-type silicon wafer of 0.005 ohm·cm resistivity in HF solution. In this paper, We considering the natural-drifts in the thickness of layers. As the pore depth increases, the availability of fluoride ions at the point of reaction decreases. Therefore, the etch rate and optical thickness were decreased with the depth, respectively. The decrease of the etch rate with the etch depth can be compensated by increasing the etching time. In our experiment, The refractive index of High porosity layer is 1.46 and low porosity layer is 2.15. After the PS growth process, the anodic electro-polishing current was applied to detach the PS structure from the substrate. The detailed characteristics, such as the reflection is discussed.