A Experimental Verification of a fluorinae-based(C₄F₈) Tgv Process for a Quartz Glass Substrate
Yu-Hsiang Tang1*, Tsung-Tao Huang1, Ming-Hua Shiao1, Chih-Sheng Yu1
1Biomedical Platform and Incubation Services Division, Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, Taiwan
* presenting author:Yu-Hsiang Tang, email:sky520830@narlabs.org.tw
In this paper, we report the fabrication process of Through Glass Via (TGV) structure and basic design rules for glass based Three-Dimensional Integrated Circuit (3D-IC) packaging as well as a process flow for glass interposer applications. Quartz glass materials have been widely used in many packaging applications for micro electromechanical systems (MEMS), optical devices, and biomedical chips. Our work focuses on a 3D-IC package approach based on the use of thin glass as a substrate material. For through-glass-vias, holes were etched in glass wafers by photolithography and inductively coupled plasma-reactive ion etching (ICP-RIE) technologies and evaluated. The results of fabrication of TGV morphology showed a very good compromise between wafer thickness, TGV shape and via diameter for vertical interposer with 50 µm diameters in 150 µm thin quartz glass wafer still very stable for thin wafer processing without complicated processes. Consequently, our etching method using a KMPR hard-mask and C4F8/He plasma enables the fabrication of excellent DC-bias and vertical profile in Quartz glass. Finally, we report an optimized etching condition for fabricating the quartz based 3D pattern structure keeping in mind their application in optical device.

Keywords: Inductively coupled plasma-reactive ion etching (ICP-IRE), Three-Dimensional Integrated Circuit (3D-IC), Through Glass Via (TGV)