Fabrication of high-aspect-ratio rectangular microgrooves on diamonds by a picosecond laser

Rectangular diamond microgroove structures with a high aspect ratio can satisfy the heat dissipation requirements of high-power chips. However, due to the high hardness and chemical inertness of diamond, high-quality microgroove machining on diamond substrates remains a significant technical challenge. In this study, a laser machining strategy combining multi-feed and angle alteration of the tilt stage is proposed. Multiple feeds in the Z direction significantly enhance the microgroove depth, while adjusting the angle of the tilt stage alters the relative laser incidence angle, enabling the fabrication of microgrooves with vertical sidewalls. Finally, an array of rectangular microgrooves on the surface of polycrystalline diamond was successfully fabricated, with a depth of approximately 1400 µm, a width of about 120 µm, and an aspect ratio of roughly 11:1. The microgrooves exhibit excellent surface quality and high machining consistency. The proposed strategy effectively addressed the issues of insufficient aspect ratio and pronounced taper in laser-machined diamond microgrooves, providing an effective approach for machining diamond microchannel heat sinks with a large aspect ratio and high collimation.