Theoretical model and experiments of glass reflow process in TGV for 3D wafer-level packaging

TGV (Through Glass Via) substrate plays an important role in wafer-level vacuum packaging. And glass reflow is the critical step of fabricating TGV. To describe the process, the theoretical formula was deduced through the analogy of fluid equation and circuit equation. Parameters of glass reflow process, such as heating treatment time and temperature for a certain width mold et al. were comprised in theoretical model, which significantly influence the reflow speed. Simulations were conducted and compatible to the theoretical results. Moreover, in all the three types of fabricating process including wet etching, laser burning and DRIE, the theoretical formula shows the feasibility for providing parameters for glass reflow process. Finally, hermetic packaging experiments were performed by sealing a gyroscope, and the Q factor measured was 9119, which indicates the feasibility of the TGV substrate for wafer-level hermetic packaging.