A reliable copper-free wafer level hybrid bonding technology for high-performance medical imaging sensors
A. Jouve, E. Lagoutte, Romain Crochemore, Gaëlle Mauguen, T. Flahaut, Christophe Dubarry, V. Balan, Frank Fournel, Emilie Bourjot, Florence Servant, M. Scannell, Karl Rohracher, Thomas Bodner, A. Faes, Jens Hofrichter
2020 · 인용 16
Current 3D integrated devices based on copper hybrid bonding are only integrating dual-damascene CMOS processes for interconnection.. In this study, we have developed a Titanium/Oxide (Ti/SiO2) hybrid bonding technology suitable for 200 mm non-copper technology platforms featuring aluminum back-ends. A combination of material stack, CMP parameters and design rules enabled us to obtain defect-free bond interface across the wafer.
Scanning acoustic microscopy, FIB-SEM and TEM cross-sections demonstrated a perfect SiO2/SiO2bonding as well as excellent Ti/Ti connections for Ti pads as small as 3×3 μm2. Moreover, we designed an electrical test vehicle including a Ti/SiO2hybrid-bonding interface, with W vias and AlCu metal interconnects. Despite the integration stack, the bonding interface remains defect-free with contact pads ranging from 10×10 μm2down to 3×3 μm2.
The 3D interconnect showed a contact resistance of 1 Ω and a parasitic capacitance of less than 2 fF. Finally, we report on the process reliability by means of thermal cycling and high-temperature storage, which confirmed the robustness of this innovative Ti/SiO2fine pitch interconnection.