Effect of Laser-Induced Etching Process on Porous Structures

Abstract

Various features of Silicon micro and nanostructures have been produced by lasers. Laser micromachining of silicon wafer has been conducted to fabricate devices for microelectronic circuits. The laser beam initiates a chemical reaction between the silicon and HF acid to synthesize porous layers by a laser-induced etching process. It is found that the etching rate increases for longer laser wavelengths when CW lasers are used and could also be used to drill micro holes in the silicon wafer when higher laser power densities are used. While Q-switched Nd:YAG laser could be employed to produce ordered nanostructures. It is found that laser parameters are adequate to produce and control the micro/nanostructure characteristics. The surface morphology investigation reveals formation of porous layers of various structures and different laser parameters were affected differently on the surface morphology. Moreover, the SEM statistics imply that high pore density of smaller average pores diameters of 3 μm are obtained when the HF concentration diluted to 30%. Furthermore, gratings of submicrons scale can be made when proper processing parameters are selected precisely. Experimental analysis has been carried out to characterize the microstructured surface using computer software.