Three dimensional metal film catalyst assisted etching of silicon

W. Sheng, T. Shi, B. Sun, X. Tan, T. Jiang, G. Liao
Huazhong University of Science and Technology, CN

Keywords: etching, silicon nanowire, catalyst

Summary:

Recently metal assisted chemical etching of silicon has emerged as a promising low-cost technology for the fabrication of vertical aligned silicon nanowire arrays[1].The technology comprises two steps: depositing a layer of 2-D porous siliver film on silicon wafers and then etching in solution. The silicon under the silver will be etched continuously along some crystal orientation so that the silicon nanowire arrays were fabricated [2]. In our experiments, when the substrate was flat <100> silicon wafer, the etching conducted along the preferred <100> crystal orientation so that the fabricated silicon nanowires were vertical along the substrate, as shown in Fig.1. To investigate the influence of the crystal orientation on the etching, we have conducted the etching on micro silicon pillar arrays by depositing a layer of 3-D porous siliver film on the surface of the structure. We found that the etching behavior was related to not only the crystal orientation of the silicon substrate but also the shape of the 3-D siliver film, as shown in Fig.2. We called it “metal assisted chemical etching based on shape restriction”. This etching behavior can be developed further for the fabrication of 3-D silicon structure.