Room-Temperature Bonding Using Mechanical Caulking Effect of Compliant Bumps for Chip-Stack Interconnection

Abstract

We propose room-temperature three-dimensional (3D) chip-stacking using the mechanical caulking effect of compliant bumps. The compliant bumps were cone-shaped bump made of Au. By caulking Au cone bumps with doughnut-shaped electrodes also made of Au, high-density large-number inter-chip connections were realized even at room temperature in ambient air. The number of inter-chip connections realized was 30,600 with 20 µm pitch. Material analysis revealed that Au cone bumps bonded to Au doughnut-shaped electrodes at the atomic level.