Advanced packaging stacks logic, memory, and photonics in three dimensions. When process margins shrink, metrology must connect global warpage with local topography—often from millimeter fields down to nanometer height resolution.
1. What becomes harder in 3D flows
Engineers simultaneously manage wafer/interposer bow, micro-bump and pillar height uniformity, TSV reveal planarity, underfill topology, and RDL roughness. No single sensor covers every regime; the practical answer is pairing interferometry for smooth, phase-friendly surfaces with optical profilers for textured or high-angle features.
2. Where laser interferometry leads
- Mirror-like optics and cover glasses: sub-nanometer repeatability with Zernike workflows tied to optical specifications.
- Wafer-scale flatness maps for modeling and correlation before bond.
- Reference artifact traceability for fleet-wide gauge alignment.
3. Where optical profilers complement
Roughness, step heights, steep sidewalls, and complex textures favor scanning / coherence-scanning profilers. Factories win when both data streams land in a common analytics layer that ties spatial distributions to electrical fallout.
4. From NPI to HVM
- NPI: lock golden recipes and run MSA on critical features.
- Ramp: control-chart coplanarity and warpage slopes against early reliability indicators.
- Production: risk-based sampling with fast scanning modes instead of blanket full-wafer density.
5. Working with Yixi
We help teams import and sustain ZYGO interferometers and profilers in China—applications reviews, recipe hardening, training, and service. Reach out for a structured metrology readiness workshop.
This article is educational and does not guarantee outcomes. Acceptance criteria must follow your fab’s quality system and vendor qualification packages.