A High Throughput Two-Stage Die-to-Wafer Thermal Compression Bonding Scheme for Heterogeneous Integration

In this work, we demonstrate for the first time a two-stage high throughput fine-pitch die-to-wafer Copper-Copper (Cu) thermal compression bonding (TCB) technique, which has a throughput of $> 300$ units-per-hour (UPH), with the potential to increase the throughput to 1100 UPH. We have optimized the bonding for high throughput, high overlay accuracy and low contact resistance with a die-to-substrate bump pitch of $\leq 10\mu \mathrm{m}$ extendible to $\sim 7\mu \mathrm{m}$ pitch. The average shear force per $2\times 2 \text{mm}^{2}$ die after high throughput TCB is $> 110$ N. The average specific contact resistance of the Cu-Cu contact is $1.24\times 10^{-9}\Omega\cdot \text{cm}^{2}$, comparable to the lowest reported in Cu/SiO2 hybrid bonding. The simplicity of TCB compared to hybrid bonding (HB) makes it a preferred approach for heterogeneous integration for 3D stacking, interposers, and the Silicon Interconnect Fabric (Si-IF) down to ~ $7 \mu\mathrm{m}$ bonding pitches.