Semiconductor integration has continued to improve over the past 50 years in accordance with Moore's Law. However, it has almost reached the resolution limit with respect to semiconductor die production. One alternative solution is multi-die packaging using either organic films or single-crystal silicon wafers as substrates. However, single-crystal silicon wafers have a very high manufacturing cost, and miniaturization of organic films has almost reached its limit due to its shape distortion.
Non-alkali glass is expected to be good alternative material for high-frequency signal transmission applications such as 5G telecommunications. We previously reported the fabrication of micro-vias by drilling using ArF and KrF excimer lasers for use as interposers. However, the optimum ablation parameters are still unclear.
Drilling of micro-vias in thin glass plates is expected to be used to produce 5G telecommunications interposers and for the panels of micro-LED displays. We have previously reported that high-aspect-ratio micro-vias can be drilled in glass using an excimer laser. In the present study, we investigated the dependence of the drilling rate and the ablation threshold on the laser fluence and pulse width. It was found that for a KrF excimer laser, the ablation threshold for glass decreased with increasing pulse width, which also increased the drilling rate and improved the quality of the drilled region. This indicates that higher productivity can be realized by the use of an optical pulse stretcher, making this approach suitable for practical applications.
Keywords
- Excimer Laser
- Glass
- Micro Via