Dry etching of fused silica glass in C4F8/Ar inductively coupled plasmas for through glass via (TGV) applications

Through glass via (TGV) technology is considered to be a cost effective enabler for micro electromechanical systems (MEMS) and radio frequency (RF) system-in-package (SIP) technology. Inductively coupled plasma (ICP) and the Bosch etching process comprise one of the most pervasive methods for via formation in silicon. Unfortunately an equivalently process for glass remains elusive. In this paper, the influences of three process parameters, bias power, argon (Ar) flow rate and substrate temperature, on fused silica glass etching in Ar/C₄F₈ inductively coupled plasmas was investigated. High glass etching rate more than lμm/min was obtained when chiller temperature was fixed at 40 °C. The results show that bias power and temperature have a significant impact on the etch rate and that the flow rate and ratio of Ar/C₄F₈ can be used to control the via profile.