A Highly Reliable 1×5μm Via-last TSV Module

A 1×5μm via-last TSV module is presented, coping with the reliability challenges imposed when exposing the metal landing pad during the liner opening etch at the TSV bottom. Two approaches are presented. A dedicated soft-landing liner oxide dry etch step is developed, eliminating the re-sputtering of copper on the TSV sidewalls. An embedded barrier is integrated, blocking the diffusion of any eventually re-sputtered copper of the landing pad. The obtained via-last TSV reliability is high for both approaches and comparable with via-middle TSV modules.