Femtosecond laser microfabrication of micro-channels on (1 0 0) silicon surfaces

Abstract

Surface texturing of silicon has a wide range of applications in various industries such as microelectronics and medical devices. This work aims to fabricate micro-channels on the silicon surfaces using femtosecond laser micromachining technique. Single pass of femtosecond laser wavelength of 1026 nm was focused on the surfaces by 4x objective that has a numerical aperture of 0.1. Different micro-channels were fabricated with different average laser powers (50, 100, 200, 400 mW) and different scan speeds (1, 5, 10, 20, 30, and 40 mm/s). The microstructure, dimensions, and surface roughness of the fabricated micro-channels were investigated by Field Emission Scanning Electron microscope (FE-SEM) and Atomic Force Microscope (AFM). Micro-channels fabricated with low scan speed of 1 mm/s has V-shape like structure and deeper compared with that fabricated micro-channels with higher scan speeds. In addition, micro-channels fabricated with average laser power of 200 mW and scan speeds of 30 and 40 mm/s has parabola like structure. It was noticed that the depth of the fabricated micro-channels increased as scan speed decreased. Laser affected areas decreased as scan speed increased. Width and depth increased with the applied average laser power. Average surface roughness (Ra) was measured to be 703 and 554 nm for the micro-channels fabricated with average laser power of 200 mw and scan speeds of 30 and 40 mm/s respectively.