Face-Down and Heterogeneous Chip Bonding Technology on Waffle-Wafer for Bumpless Chip-an-Wafer (COW) Package

A high-speed, manufacturable, fully chiplet integration process using Face-Down bonding to 300 mm waffle-wafer and bumpless Chip-on-Wafer (COW) has been developed for the first time. The inkjet method successfully formed a thin adhesive layer on the bottom of the waffle wafer, with no voids even at a 5 μm adhesive thickness. Over 30,000 chips with a narrow gap of 40 μ m were bonded with a misalignment of less than 10 μ m and a short bonding time of a few milliseconds per chip.