Thermal conductance across bonded SiOx-SiOx interfaces in hybrid bonding process

TL;DR

This study investigates the thermal boundary conductance of SiO-SiO interfaces in hybrid bonding, revealing a lower limit of 150 MW/m2-K, which informs thermal management in 3D integrated circuits.

Contribution

It provides the first quantitative measurement of thermal conductance across bonded SiO-SiO interfaces using time domain thermoreflectance.

Findings

Lower limit TBC of 150 MW/m2-K established

Thermal resistance less than a 9.2-nm dielectric layer

High-quality bonded interfaces confirmed

Abstract

Hybrid bonding is a pivotal technology for enabling three dimensional integrated circuits. Among the foremost challenges facing 3D IC implementation is thermal management, where a deep understanding of heat conduction across bonded interfaces is essential for addressing heat dissipation and reliability issues. Nevertheless, the thermal conductance of bonded dielectric-dielectric interfaces remains poorly understood. In this study, we employ the low-temperature bonding technique integral to hybrid bonding to fabricate SiO-SiO interfaces and investigate their thermal boundary conductance using time domain thermoreflectance. Structural characterizations show high quality bonded interfaces. By fitting the data with an equivalent multilayer thermal model, we establish a lower limit TBC of 150 MW/m2-K for the SiO-SiO interfaces, which corresponds to a thermal resistance lower than that of a 9.2-nm-thick dielectric layer. These findings offer valuable insights into thermal transport in hybrid-bonded structures and provide critical guidance for the thermal design of advanced packaging solutions.