Sub $1\ \mu \mathrm{m}$ Pitch Achievement for Cu/SiO2 Hybrid Bonding

Abstract

With hybrid bonding pitch reduction, many challenges are arising especially the ones related to Cu-Cu connections with submicron Cu pads. A methodology is presented here to achieve submicron hybrid bonding pitch starting from single Cu pad thermomechanical behavior study to quantifying Cu-Cu contact resistivity. Depending on the single crystal Cu orientation, several nanometers difference in total deformation is obtained. The Cu dishing limit should be restricted with respect to the lowest deformation. Contact resistivity studies allow to further refine the Cu dishing to get a contribution of contact resistivity below $10^{-11}\ \Omega.\text{cm}^{2}$. By respecting these criteria, a 100 % yield was achieved down to 0.81 µm Cu/SiO2 hybrid bonding pitch. A successful method for the capacitance increase compensation with pitch reduction is also presented based on the adaptation of the geometric parameters of the hybrid bonding interconnects.