Additive-assisted laser-induced wet etching for fabricating high-verticality through glass vias

The vertical three-dimensional interconnection architecture, with its significant advantages in spatial utilization efficiency and signal transmission performance, has become a core enabling technology in modern electronic system design. Notably, thanks to the excellent dielectric properties and mechanical stability of glass materials, Through Glass Via (TGV) interposer technology has surpassed Through Silicon Via (TSV) technology and has become the most promising solution in the field of high-density three-dimensional integration. However, the current TGV fabrication process generally faces verticality deviation issues during micro-hole formation, which directly leads to reduced metal filling reliability and degraded signal integrity. This study innovatively introduces poly dimethyl diallyl ammonium chloride (PDDA) as an etching modifier based on laser-induced wet etching technology, enabling the control of the glass etching rate. Experimental results show that the optimized process can achieve a middle-to-surface hole diameter ratio of 0.77 in a TGV with a deep-to-width ratio of 23, significantly improving the verticality of the via morphology.