Experimental Study On Excimer Laser Electrochemical Etching Process Of Silicon

Excimer laser electrochemical etching process is a combination of excimer laser direct etching and electrochemical etching. In order to study the process etching silicon, 248nm KrF excimer laser is adapted as light source, and KOH solution is used as electrolyte. Based on the experimental results, the basic etching figure and several key factors are discussed. The thesis comprises 3 parts: (1) The basic principle of the process is described. This section discusses three etching actions in the process: excimer laser direct etching, KOH electrochemical etching and the coupling etching of the excimer laser and electrochemistry. (2) The experiment device is designed. It includes the excimer laser machine, the cell and the light track. Silicon sample as the anode is immersed into KOH electrolyte in a cell which contains an optical window to allow it to be illuminated by laser beam. A voltage is applied between the silicon electrode and a counter electrode (e.g., a piece of net-shaped platinum as the cathode) immersed in the same electrolyte. (3) Based on the experimental results, the basic etching figure and several key factors are discussed. Besides, the analysis compared with excimer laser direct etching, excimer laser etching in water and excimer laser electrochemical etching metal, is discussed in this section. The thesis shows that the process can produce high aspect ratio microstructure with high quality etching surface, high etching rate and easy controlling, but the laser peening, the solution spurting and refraction will make bad etching surface. In the end, a summary of the thesis and the future view of excimer laser electrochemical etching process of silicon are given.