Evaluation of warpage tolerance of 100 μm dies to achieve void-free bond and 100% assembly yield

Bonding dies to wafers can lead to voiding and non-bonded areas due to warpage. In this work, the maximum die-level warpage required to achieve a fully bonded and void-free interface for a given dielectric stack is evaluated. 100 μm thick dies were prepared on a temporary carrier and bonded to a wafer using a ‘wafer-to-wafer’-like bonding flow, a collective die-to-wafer, and a direct die-to-wafer flow. The method used and the forces involved during bonding, primarily determine the tolerance of die-level warpage to achieve a void-free bond.