Defect inspection - optical (broadband plasma, laser scanning)

Why the concentration exists

Broadband plasma illumination across DUV, UV, and visible wavelengths scans patterned wafers for particles and pattern defects. The broadband spectrum allows detection across multiple process layers because different defect types respond to different wavelengths. Laser scanning systems complement plasma-based tools by providing high-throughput ramp monitoring during production. Real-time defect data feeds directly into yield management software for excursion control. Together, these optical modes cover the bulk of inline inspection in high-volume manufacturing.[1][6]

What the evidence shows

Who supplies it

KLA supplies the 29xx Series broadband plasma inspectors for multi-layer sensitivity. The C30x Series provides tunable broadband inspection on 200 and 300mm wafers. The Voyager and Puma laser scanning patterned wafer inspectors target production ramp and high throughput. The 392x and 295x systems were announced on July 8, 2019. These cover inspection applications from shallow trench isolation through metallization, including EUV lithography quality control.[1][10]

Onto Innovation, formed from the 2019 merger of Rudolph Technologies and Nanometrics, brings specialty optical metrology to the wafer inspection market. The combined entity operates from Wilmington, Massachusetts. It has particular strength in optical metrology and film thickness characterization across wafer front-end and advanced packaging. This positions Onto as a secondary supplier in optical inspection adjacent to KLA's dominant position.[3]

What it depends on, and what depends on it

Broadband plasma optical inspection systems combine deep ultraviolet through visible spectrum illumination sources with high-speed sensor arrays. Computational infrastructure handles real-time defect classification at production throughput. The systems integrate with scanning electron microscopes for final defect review after optical detection. Deep learning modules such as DefectWise support design-aware classification on advanced nodes.[1][6]

Optical wafer inspection equipment holds the largest share of the semiconductor wafer inspection equipment market at 45%. Defect detection accounts for approximately 80% of inspection processes within that market. This makes optical defect inspection the dominant application category in semiconductor inspection. Bright-field optical inspection is used for full-wafer coverage at high throughput. It remains cost-effective for volume production despite the 20-30nm sensitivity floor.[9][12]

Where it sits in the stack

What would break it

DUV laser illumination has caused issues like surface material ablation on inspected wafers. DUV systems also struggle with precision below 65nm feature sizes. Manufacturers are exploring broadband plasma illumination as an alternative to pure DUV. Production-capable electron beam tools are also being deployed where optical sensitivity is insufficient.[7][8]

THz wave-based inspection systems have not yet been proved for finding defects on patterned wafers. Their speed could match conventional optical solutions in principle. The approach exploits plasma frequencies in the THz band to boost signal-to-noise ratio. Localized surface plasmon resonance on defect features could enable sub-optical resolution detection.[5]

What to watch

KLA's next-generation broadband plasma platforms are currently being evaluated by customer partners. Evaluation focuses on defect detection capability for the most advanced logic and memory devices. The new BBP inspectors target fast defect learning cycles during research and development. Inline excursion monitoring during high-volume manufacturing is the production use case.[4]

Extreme ultraviolet lithography is entering high volume manufacturing for sub-7nm scaling. Characterizing and monitoring defects that print at wafer level has become critical to yield. Stochastic printing defects from the pattern formation process require new inspection capabilities. Multi-layer defects and added particles on EUV masks add further inspection demands.[2]

Optical wafer defect inspection at the 10nm technology node and beyond is being reviewed. The review covers three areas: defect detectability evaluation, diverse optical inspection systems, and post-processing algorithms. Sub-10nm high-volume manufacturing is becoming mainstream. This timeline sets the window when current optical approaches may reach their resolution ceiling.[11]

Related nodes

Sources

1. directindustry.com · 2026-05-14T15:37:31
2. ieeexplore.ieee.org
3. semiconductorx.com
4. kla.com · 2025-10-20T19:17:09
5. iopscience.iop.org · 2022-04-21T00:00:00
6. kla.com
7. robovision.ai · 2025-03-24T10:49:15
8. newport.com
9. averroes.ai · 2025-06-25
10. ir.kla.com · 2019-07-08
11. sciopen.com · 2022-09-01
12. market.us · 2024