Replacing the PECVD-SiO2 in the through-silicon via of high-density 3D LSIs with highly scalable low cost organic liner: Merits and demerits

A novel approach to suppress the conventional Cu-TSV induced thermo-mechanical stress in 3D-LSI chip is proposed, fabricated and tested. In this approach, a thermal-chemical-vapor-deposition grown organic poly-imide based polymer is conformally deposited along the side wall of the TSV. As-grown polymer was tested for its physical properties and mechanical properties, and was also evaluated for their role in minimizing the thermo-mechanical stress in vicinal and via-space Si. It was found that replacing the conventional SiO₂ dielectric liner (sandwiched between the via-metal and Si) with organic polymer greatly helps in suppressing the thermo-mechanical stress, and thus the keep-out zone.