Excimer laser electrochemical etching n-Si in the KOH solution

To further understand the behavior of laser-induced electrochemical etching process, the experiments of micromachining silicon by laser-induced electrochemical etching were carried out. 248 nm excimer laser as light source was adopted in this work with the power of 109 W/cm2 for the first time and the KOH solution was used as an electrolyte. Based on the results of experiments, basic etching appearances by laser electrochemical etching silicon were researched. The etching rate was analyzed in detail by numerical simulation and experiments. It is verified that the compound technique is a combination of laser, electrochemical and coupling etchings, and laser etching is dominating in the compound process. Besides, both liquid-enhanced and jet shock pressures can preferably improve the etching rate. At the same time, the anisotropic etching stop of silicon in alkaline solution was solved in this study. As a result, this process can be applied to transfer pattern without mask, and it possesses the ability of machining large aspect ratio microstructures.