Hao-Tsung Chen, Ying-Hung Chen, Ping-Yen Hsieh, Ju-Liang He, Feng Chia University, Taiwan
Through-Glass Via (TGV) technology has emerged as a crucial interconnection approach for high-density and high-frequency electronic packaging. Its excellent electrical insulation, low dielectric loss, and high dimensional stability make it indispensable for next-generation 3D integration and heterogeneous system-in-package (SiP) applications. Conventionally, the formation of TGVs relies on laser-induced deep etching (LIDE), which involves two sequential steps- laser modification followed by wet chemical etching. However, this dual-step process complicates fabrication, necessitates the use of hazardous hydrofluoric acid, and typically results in hourglass-shaped vias with constricted mid-sections.
In this study, a dry etching alternative was investigated to mitigate these drawbacks. A 60 MHz/2 MHz very-high-frequency capacitively coupled plasma (VHF-CCP) system was employed for post-laser-modification etching of glass substrates. The etching gases, consisting of fluorocarbon and argon mixtures, were optimized to evaluate their influence on etch rate and via-profile evolution. Power level was systematically varied to establish correlations between process parameters, etching kinetics, and via morphology.
The results demonstrate that VHF-CCP etching can effectively tailor the via profile while eliminating the need for hazardous wet processing, suggesting a promising pathway toward scalable, environmentally benign TGV fabrication.