Three-dimensional micro-nano structures with **high aspect ratios (HAR)** are shaking up fields like sensors, semiconductors, and microelectromechanical systems (MEMS).
These structures—especially HAR micro-trenches—help boost signal speeds, energy density, and device integration.
But here’s the thing: measuring these ultra-fine, deep structures **accurately and efficiently** without damaging them is still a real headache.
Now, a new study introduces an optical approach using a **micro-axicon lens array** to get around old measurement roadblocks.
This could open the door to more reliable and scalable fabrication processes for next-gen electronics.
Why High Aspect Ratio Microstructures Matter
In microfabrication, the *aspect ratio* is just the relationship between a structure’s depth and width.
**HAR micro-trenches** have aspect ratios over 10:1, pushing designs from flat 2D planes into the vertical realm.
This move from planar to volumetric lets engineers cram more functionality into the same physical footprint.
Such designs are vital for:
- Higher energy density—batteries and capacitors can store more charge in the same space.
- Faster signal speeds—which means better semiconductor performance.
- Increased device integration—so we get more complex MEMS and multi-layer circuits.
The Problem With Current Measurement Methods
HAR designs bring huge performance gains, but they also create tough **metrology challenges**.
Manufacturing reliability depends on accurate, repeatable measurement of tiny dimensions, but measuring deep and narrow trenches without messing them up is tricky.
Today’s measurement techniques include:
- Non-optical methods like Scanning Electron Microscopy (SEM), Focused Ion Beam (FIB), Atomic Force Microscopy (AFM), and profilometry. These offer high precision but are often destructive, depth-limited, or just too slow for repeated checks.
- Electrical methods that don’t destroy the sample but can’t measure deep enough and need complex integration.
- Optical methods—white light interferometry, confocal microscopy, reflectance spectroscopy, infrared sensing, scatterometry, holography—avoid contact but often struggle with depth accuracy, range, or just get too complicated.
Recent Progress in Optical Metrology
Optical advances in the last few years have pushed aspect ratio measurement up to **28:1**.
Still, many systems hit real-world limits—small field of view, noise, and calibration headaches.
So, researchers keep searching for a method that’s precise, scalable, and truly non-destructive.
The Micro-Axicon Lens Array Breakthrough
The new approach uses a **micro-axicon lens array** to generate *lattice light fields*.
By looking at how these light points shift—thanks to diffraction as light passes through HAR trenches—researchers can figure out trench depth and width pretty accurately.
What really stands out here is performance: measurement errors stay **below 9%** compared to SEM benchmarks, and the structures stay unharmed.
That’s a big deal for fragile, high-precision components.
Advantages Over Conventional Methods
This optical system brings several key benefits:
- Non-destructive testing—delicate microstructures survive quality control.
- Scalability—works for high-volume manufacturing lines without major changes.
- High precision—as good as gold-standard SEM, but way faster and gentler.
- Versatility—fits semiconductors, MEMS, biosensors, and other micro-engineered devices.
Impact on Future Technologies
With accurate, repeatable measurements of extremely deep micro-trenches, this innovation could really speed up adoption of **next-generation nano-architectures**.
From tightly integrated chips to advanced biomedical sensors, HAR metrology improvements might help reduce defect rates, lower costs, and boost reliability.
Conclusion: A Step Toward True Precision Manufacturing
The micro-axicon lens array system for HAR measurement marks a major leap in micro-nano metrology. It breaks through many of the roadblocks that traditional and modern optical tools keep running into.
Honestly, as device geometries keep shrinking and aspect ratios climb, accurate and non-invasive measurement isn’t just nice to have—it’s essential. This technology feels like a real contender for the next wave of high-performance, tightly packed devices.
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Here is the source article for this story: Fast and accurate measurement of high aspect ratio MEMS trench array with optical lattice illumination