Chemical etching of silicon induced by excimer laser radiation

Excimer laser-induced chemical etching of silicon in a chlorine ambient at low laser energy fluences is based on two primary physical mechanisms, namely: 1, surface chemical reactions; and, 2, photoinduced desorption processes. A significant silicon etch rate wavelength dependence is observed at 308 and 248 nm radiation and results from differences in the above etching mechanisms. At 308 nm the surface reaction is enhanced by photodissociation of chlorine which is inefficient at 248 nm. The wavelength dependent differences in the surface reactions can be eliminated by generating a high concentration of gas phase radicals using a microwave generator.