Wet Etching Process Optimization and Consistency Enhancement of Massive Through Glass Vias Through Laser-Induced Wet Etching

Abstract

Through glass via (TGV) technology presents a promising alternative for 3-D vertical interconnects in advanced packaging. As device integration progresses, the number of through vias in glass interposers is on the rise, which presents challenges in achieving high-quality and consistent processing of massive TGVs. This study utilizes laser-induced wet etching, complemented by multienergy field mixing assistance to produce highly consistent and significant quantities of TGVs on Corning Eagle XG (EXG) glass. Initially, a specialized wet etching system was developed, featuring an ultrasonic field, temperature control for a water bath, and sample reciprocation. The impact of these parameters on the morphology of the TGVs was systematically investigated. In addition, the study explored the mechanisms by which various etching parameters—such as temperature, etchant concentration, and ultrasonic power—affect the consistency of the TGVs. Ultimately, through the optimization of etching parameters via orthogonal experiments and statistical data sampling, it was confirmed that integrating an ultrasonic field, sample reciprocation, and rotation during the etching process significantly enhances the quality and consistency of the massive TGVs. The consistency of all TGVs (26898 per substrate) was enhanced with a relative standard deviation of 0.73% for the surface hole diameter and an etching rate of $1.24~\mu $ m/min. This advanced etching technology for high-consistent massive TGVs greatly improves the productivity and practicality of devices utilizing TGVs in 3-D packaging applications.