Experimental investigation on laser micromilling of SiC microchannels

Silicon carbide (SiC) microchannels show their promising merits in the applications of microchannel heat sink cooling systems, microsensor MOS devices, and UV photodiodes. The fabrication of SiC microchannels is critical for their wide applications. In this study, a laser micromilling method is utilized to process SiC microchannels. A series of SiC microchannels are fabricated using a pulsed fiber laser. Based on the SEM observations and 3D confocal microscope measurements, the formation of microchannels is analyzed. The effects of laser processing parameters, such as laser output power, scanning speed, and scanning times as well as the predetermined microchannel width, on the geometric dimension and surface morphology are systematically assessed. The common recast layer deposited around the laser-scanned areas in the laser micromilling of metallic structures was not found for the SiC microchannels. A transition between triangular and trapezoidal shapes occurred for the laser-micromilled microchannels depending on the processing parameters and predetermined width. The microchannel depth increased monotonically with the laser output power and laser scanning time but decreased with increasing scanning speed. On the contrary, the bottom width of microchannels presented an inverse trend. The surface roughness was dependent on the laser scanning speed, scanning time, as well as predetermined width.