Micro-via processing in glass material using long pulse KrF excimer laser for semiconductor interposer packaging (Invited Paper)

We present a micro-via fabrication technology for glass materials. The technology, which is based on KrF excimer laser direct ablation drilling, demonstrates high productivity, achieving more than 1000 micro-vias per second on glass substrates using an excimer laser and a Diffractive Optical Element (DOE). This high productivity is further enhanced by the pulse shape (time domain) of the excimer laser. Extending the laser pulse width from 32 ns Time-Integrated Square (TIS) to 130 ns TIS is shown to increase the ablation rate by a factor of 2.2. We analyzed and identified the mechanism of this productivity enhancement by observing the emission light during ablation using a high-speed spectrometer and a high-speed camera. The results demonstrate that the combination of excimer laser pulse formation and DOE technologies enables high-productivity fabrication of fine micro-via holes for high-performance advanced packaging.