Research on 355 nm all-solid-state ultraviolet laser processing through silicon holes

In this work, the single variable method is used to investigate the effect of various laser parameters on the diameter, taper, and the quality of the through hole when silicon holes are machined with a 355 nm all-solid-state UV laser. Studies have shown that with an increase of laser fluence, the resolidification at the hole edge is alleviated, and the hole diameter increases slightly with it. The high repetition frequency aggravates the recasting on the hole walls and edges, and the hole taper is also increased due to the high repetition frequency. Excessive scanning speed causes the hole wall to be uneven and results in a large amount of melt attached to the sidewall. However, in case the scanning speed is too slow, the quality of the hole deteriorates due to severe heat accumulation. With proper negative defocus distance, the through hole with a relatively smooth sidewall and a small taper can be obtained. The results provide a technological reference for processing high quality through silicon holes by a 355 nm all-solid-state UV laser.