Controllable Fabrication of Silicon Nanopore Arrays by Two-Step Inductively Coupled Plasma Etching Using Self-Assembled Anodic Aluminum Oxide Mask

Silicon nanopore arrays (SiNPs) were prepared by a two-step inductively coupled plasma (ICP) etching process using a self-assembled anodic aluminum oxide film mask. The influence of etching parameters (first-step etching time, Cl 2 proportion in the etching gas, etching pressure, ICP power, and radio frequency (RF) power) on the morphology of the SiNPs were systematically investigated. The results revealed that the first step of ICP etching can effectively remove the barrier layer of the mask. Higher Cl 2 proportion and lower etching pressure increase the chemical corrosion and physical bombardment of ICP etching, respectively, which may damage the porous morphology. ICP power affects both chemical reaction etching and physical bombardment, but the RF power mainly affects physical etching. The etching rate is positively correlated with Cl 2 proportion and RF power, and negatively correlated with etching pressure. The optimized first-step etching time, Cl 2 /Ar ratio, etching pressure, ICP power and RF power for high-quality SiNPs are approximately 10 s, 60%, 7 mTorr, 900 W and 100 W, respectively. Precise control of the pore size and depth of the SiNPs can be achieved using this controllable growth process. These results demonstrate a simple and controllable way to achieve good quality SiNPs with desired sizes.