Controlled and Fast Fabrication for P-Type Porous Silicon Structures with a High Aspect Ratio by Electrochemical Etching

In this experiment, electrochemical etching of ordinary P-type monocrystal silicon was firstly studied in a mixed etching solution of hydrofluoric acid (HF) and dimethylformamide (DMF). The rapid electrochemical etching of P-type porous silicon with a high aspect ratio (37–68) and high etching rate (19–28 μm/min) was achieved, and the depth was up to 110 μm. Based on these results, photolithographic treatment was carried out on the surface of P-type monocrystal silicon with medium resistance, and electrochemical etching was carried out on the treated silicon wafer in a mixed HF and DMF etching solution. Finally, high-aspect-ratio (15–41) regular-array P-type porous silicon was successfully obtained at a high etching rate (17–26 μm/min), and rapid preparation of P-type regular-array porous silicon was achieved. This method offers an effective approach for fabricating high-aspect-ratio silicon structures, which is important for microelectromechanical systems (MEMS) design.