Advanced Packaging Process Control Through Full-Field Wafer Shape Using WFPI

By MIGUEL JIMENEZ-GOMIS, Senior Application Engineer, Wooptix

Backside power delivery networks and HBM stacks depend on wafer bonding with tight pitches and overlay budgets, and even small bonding-induced distortions can turn into yield loss in downstream CMP, lithography and stacking. Traditional metrology often can’t deliver fast, full-wafer, non-destructive measurements at the speed high-volume manufacturing requires.

Miguel Jimenez-Gomis of Wooptix describes how wavefront phase imaging (WFPI) captures full-wafer shape at every stage of the process, including high-order distortions such as the four-fold pattern that appears in direct wafer-to-wafer bonds. Unlike simple bow, which can be corrected with chuck or clamp adjustments, these deformations are intrinsic to the materials and bond dynamics, and WFPI data can be used to model the in-plane stress behind them.

Because WFPI works on patterned wafers and novel substrates such as glass, where conventional interferometry struggles, he argues it can serve as a feed-forward process control lever, letting fabs adjust bonding parameters in real time, build predictive models and keep downstream tools operating within tighter tolerances.

Click here to read the full article in Semiconductor Digest magazine.

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