A High Throughput Two-Stage Die-to-Wafer Thermal Compression Bonding Scheme for Heterogeneous Integration
Krutikesh Sahoo, Haoxiang Ren, Subramanian S. Iyer
Abstract
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 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$> 300$</tex> 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 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\leq 10\mu \mathrm{m}$</tex> extendible to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim 7\mu \mathrm{m}$</tex> pitch. The average shear force per <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2\times 2 \text{mm}^{2}$</tex> die after high throughput TCB is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$> 110$</tex> N. The average specific contact resistance of the Cu-Cu contact is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.24\times 10^{-9}\Omega\cdot \text{cm}^{2}$</tex> , 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 ~ <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$7 \mu\mathrm{m}$</tex> bonding pitches.