A recent Semiconductor Engineering article, “Metrology Digs Deep to Produce Next-Generation 3D NAND,” highlights the growing difficulty of measuring and controlling increasingly complex 3D NAND structures as the industry pushes toward higher stack counts and ever more extreme aspect ratios. The message is clear: as 3D NAND architectures scale vertically, metrology must evolve just as aggressively.
At Chipmetrics, we agree – and we would add that advanced metrology only delivers real value when paired with standardized, application-relevant process control structures.
The Metrology Challenge Is Really a Process Control Challenge
As the article explains, next-generation 3D NAND depends on deep, narrow channel holes with aspect ratios well beyond what conventional planar devices ever required. Deposition and etch processes must deliver highly uniform films at the bottom of these structures, with tight control over thickness, composition, and defectivity.
Metrology tools are being pushed to probe deeper into these features using optical, X-ray, and electron-based techniques. But even the most advanced tools face a fundamental limitation: without known, repeatable reference structures, it is difficult to translate measurement signals into actionable process insight.
In practice, this means fabs often struggle to distinguish between:
- Tool-to-tool variation
- Recipe drift over time
- Precursor transport limitations
- True process window constraints
Why Standardized Test Chips Matter More Than Ever
This is where standardized test chips play a critical role. To understand and control ALD, CVD, and etch behavior in extreme HAR structures, engineers need well-characterized geometries that intentionally stress the process in a controlled, repeatable way.
Chipmetrics’ PillarHall® high-aspect-ratio test chips are designed to do exactly that. By providing lateral and vertical HAR structures with precisely defined dimensions, these chips enable direct measurement of:
- Film conformality and step coverage
- Precursor penetration depth
- Loading effects and depletion behavior
- Sensitivity to temperature, pressure, and flow changes
Because these structures are standardized, results can be compared across tools, materials, fabs, and development cycles — something device wafers alone cannot reliably support.
From R&D Learning to High-Volume Manufacturing
The Semiconductor Engineering article emphasizes that variability increases as stacks grow taller and processes become more complex. This variability doesn’t just impact yield — it slows learning cycles and increases risk during technology transitions.
Standardized test chips shorten those cycles by enabling:
- Faster root-cause analysis when metrology signals change
- Earlier detection of subtle process drift
- Objective benchmarking of tools and materials
- More confident scaling from R&D to production
Rather than replacing advanced metrology, these structures amplify its value, turning measurements into clear, quantitative process feedback.
Enabling the Next Phase of 3D NAND Scaling
As 3D NAND continues to scale vertically, the industry will need both deeper metrology and better process control strategies. The combination of advanced measurement techniques with application-relevant, standardized test structures provides a practical path forward — reducing uncertainty, improving yield, and accelerating time to volume.
At Chipmetrics, we see standardized HAR test chips not as optional accessories, but as foundational infrastructure for next-generation memory manufacturing.