Fabrication of Cross-Scale and High Aspect Ratio Through-Glass Vias Using Femtosecond Laser Spatio-Temporal Shaping Approach

The research targeted the problem of the low aspect ratio of sub-micron through-glass vias in advanced packaging. By adopting the double-pulse delay regulation method, through-glass vias with an aspect ratio as high as 2300:1 and a pore diameter of only 300 nm were successfully achieved in BF33 glass, which significantly improved the aspect ratio of sub-micron through-glass vias. Moreover, in response to the issues of the processing of 1–10 μm through-glass vias and the poor quality of sidewalls, a method combining near-threshold energy double-pulse train modification processing with sodium hydroxide etching was proposed. Through this method, high-quality glass micro-holes with a size range of 1–10 μm were successfully obtained. Additionally, by precisely controlling the number of double-pulse trains and the etching time, effective regulation of micro-holes within the size range of 1–20 μm could be achieved, greatly improving the processing quality of glass micro-holes within this range and overcoming the bottleneck that traditional processing methods had difficulty in achieving high-quality glass micro-holes within 10 μm. Facing practical application scenarios, the above method was further utilized to fabricate high-quality through-glass vias with a size of 230 μm on 100-micron-thick BF33 glass, which strongly verified the effectiveness and importance of this method in micropore processing.