Publications OK SMART LAB

Thermally and structurally robust design of through glass via arrays using multi-objective optimization and machine learning-based geometry prediction
Authors
Yong Tae Kim, Jun Seok Lee, and Jong G. Ok
Journal
International Journal of Precision Engineering and Manufacturing–Green Technology
Vol. (No.), pp.
Online published, (Jun 2026)
Year
2026
A thermally and structurally robust design of the through-glass via (TGV) array is presented for reliable Cu–Cu hybrid bonding applicable to three-dimensional (3D) multilayer semiconductor packaging. Through rational heat transfer modeling and variation of the via materials (Si and glass), section shapes (circle and polygon), and arrays (2 × 2, 3 × 3, and 4 × 4), the thermal conduction and stress behavior of hybrid Cu-Cu bonding structures are systematically analyzed based on the finite element method (FEM), multi-objective genetic algorithms (MOGA), and machine learning. While the MOGA can efficiently minimize the thermo-mechanical stress and deformation beyond the baseline FEM-based design, the random forest model trained on Pareto-optimal solutions successfully validates and refines the MOGA-level design result with significantly reduced computational cost. The TGVs outperforms the through-silicon vias (TSVs) with more effective mitigation of mismatch in thermal expansion. For supporting the laser ablation-assisted fabrication feasibility, a 15-sided polygonal TGV structure is introduced and compared with the circular via structures, which exhibit improved thermo-mechanical stability. The proposed machine learning model can rapidly and precisely predict multiple indicators, in this case temperature, deformation, and stress, with significantly reduced computing resource and time (~ 4 s compared to FEM (144 s) and MOGA (300 s)), making it readily expandable to scalable arrays and stacking numbers. This work provides a practical and versatile framework for the design and fabrication of robust TGV structures for diverse 3D semiconductor chip packages including high-bandwidth memory devices requiring stacking of ten or more layers with high thermo-mechanical reliability.