Porous silicon (PS) is very important due to its applications in optoelectronics, biological and chemical sensors, micromachining, in fabrication of diffusion membranes and as a substrate material and trap for molecules in matrix-free desorption/ionization mass spectrometry. PS can also be used in photovoltaics, biomedical applications, and in batteries and solar cells. PS is normally produced either by anodic etching in HF-based solutions or by stain etching in HF/oxidizing agent. While Metal-assisted chemical etching method does not need external bias and enables formation of uniform PSL more rapidly than the stain etching method.