Enhancement of Glass Ablation Rate During Micro-via Processing using Very Long Pulse 248-nm Excimer Laser for Semiconductor Interposer Packaging

Much research on improving the productivity of micro -via fabrication in glass using 248-nm excimer laser ablation has been performed for semiconductor interposer packaging. We previously reported that the ablation rate for glass using long excimer laser pulses (74 ns time -integrated square (TIS)) is 1.53 times higher than that for short pulses (32 ns TIS) under the same laser fluence conditions. Here, we report further enhancement of the ablation rate using a very long pulse width (130 ns TIS) excimer laser. The ablation rate for 500 -mu m -thick glass using this laser is about 2.17 times higher than that for a conventional short -pulse excimer laser. We also investigate the dependence of the relationship between the ablation rate and the laser irradiation energy ratio on the time since the beginning of the pulse, and we find that after 30 ns, the relationship becomes linear. This is consistent with our previous results for the glass micro -via fabrication mechanism.