Dielectric Bonding Method for 3D Integration Packaging Using Self-Assembled Monolayer

Abstract

The emergence of big data and artificial intelligence has promoted the semiconductor industry to increasingly adopt advanced three-dimensional stacking packaging technologies due to the limitations of device scaling. Traditional packaging methods, which rely on micro bumps and adhesives, struggle to meet the growing demands for sub-micrometer fine pitches. To address these challenges, bump-less direct bonding techniques, such as Cu/SiO₂ hybrid bonding, have gained attention, along with surface-activated bonding (SAB) using plasma treatment. However, plasma treatment poses risks, including Cu oxidation and potential short circuits from Cu particle transfer in fine-pitch applications. This study presents a novel plasma-free method that utilizes self-assembled monolayers (SAMs), thin molecular layers that spontaneously create ordered structures on surfaces, for dielectric surface activation. We deposited 3-aminopropyltriethoxysilane (APTES) on silicon dioxide (SiO₂), resulting in a hydrophilic layer that enhances bonding. Notably, a heat treatment significantly improved interfacial adhesion strength through the formation of an amorphous silicon (Si) layer. This SAM-based bonding technique, which enables dielectric surface without the need for plasma, holds promise for future fine-pitch hybrid bonding applications in 3D integrated packaging.

Graphical abstract