Solvent-Assisted Laser Drilling of Silicon Carbide

Abstract

Laser drilling of single crystalline silicon carbide (SiC) wafer in air, under water, and under methanol with a 355 nm wavelength laser is investigated and compared. Among these different media, laser drilling of SiC under a solvent, methanol, is found to produce holes with a relatively cleaner and smoother surface. Ablated particle redeposition at the entrance and exit of the holes is minimized. Minimum oxide (i.e., silicon dioxide) or heat-affected zones are observed and the surface finish inside the holes is much smoother and more uniform as compared with those drilled in air and under water. The improvement of drilling quality can be attributed to the relatively lower boiling temperature and better wettability of the solvents, which enhance the effects of cooling (thermal damage free) and ablated particle cleaning during laser drilling. It is found that the quality of laser drilling of SiC varied with the thickness of solvent layer, that is, water and methanol. A solvent layer of 500 mm is suggested to be used for the enhancement of laser ablation rate and quality.

Efficient Water-Assisted Glass Cutting with 355 nm Picosecond Laser Pulses

“…Water is most commonly used as a laser ablation assisting liquid since it is cheap, harmless, and recyclable [ 20 , 28 ]. Water can be introduced into the ablation zone in multiple ways: by submerging the workpiece into standing [ 22 , 26 , 29 , 30 ] or flowing water [ 20 , 21 , 31 , 32 ]; by guiding a laser beam in the water jet [ 33 , 34 ]; or by spraying water mist [ 18 ] or a water jet [ 19 , 28 ] next to the laser beam. Most studies have investigated laser ablation with workpieces submerged into a standing or low-velocity liquid flow with a liquid layer thickness of a few to tens of millimetres.…”

Hybrid micro-machining processes: A review

“…Table 3 gives an overview of the micro-machining processes carried out with the assistance of various fluids. PET [104], PMMA [104] Increase of material removal rates up to twice [99] Improvement in surface quality [104] No laser ablation enhancement for PET [104] Reduction in micro-cracking and HAZ size [101] Gas-assisted laser drilling Nimonic 263 coated with a TBC [105] Delamination-free drilled holes [105] Methanol-assisted laser machining Single crystalline silicon carbide [106] Improvement in drilling quality [106] Salt solution-assisted laser machining 316 stainless steel [107] Up to 300% increase in material removal rate [107] Chemical-assisted ultrasonic machining Glass [108] Up to 40% improvement in surface finish and material removal rate [108] Electrochemical-assisted machining 304 stainless steel [109] Decrease cutting force [109] Electrorheological fluid-assisted ultrasonic machining…”

“…It is believed that plasma confinement is generated in a liquid environment at a higher radiant exposure regime (i.e., 1>GW/cm 2 ), consequently inducing higher temperature, higher pressure, and higher density plasma (i.e., laser-induced plasma) at the Si surface when the laser pulse irradiated the surface of the solid target through the liquid, leading to more explosive removal of material. A methanol layer of 500 µm is suggested to be used for the enhancement of laser ablation rate and quality in chemical-assisted laser micro-drilling of single crystalline silicon carbide [106]. Salt solution can be also used so as to improve the machining quality and material removal rate in laser micro-machining.…”

Laser Drilling of Metallic and Nonmetallic Substrates

“…with a thin overlay of water or some other liquids, using lasers of different wavelengths and pulse durations (69,78,80,81,(142)(143)(144)(145). with a thin overlay of water or some other liquids, using lasers of different wavelengths and pulse durations (69,78,80,81,(142)(143)(144)(145).…”