Interconnect microvia drilling with a radially polarized laser beam

High-density interconnection via drilling using a diode-pumped solid-state laser is one of the industrially accepted techniques for 3D packaging and backside contacting applications. The advancement in microelectronic systems requires this technique to be improved constantly. In this paper, we introduce the technique of applying a radially polarized UV laser beam for interconnect via drilling. Microvias drilled with a p-polarized beam were compared to those drilled with a radially polarized beam. Results revealed that a radially polarized laser beam significantly improves the performance of laser drilling in all aspects, including feature size, efficiency, the cross-section profile and cleanness of the finishing.