Three-dimensional deep sub-wavelength defect detection using λ = 193 nm optical microscopy.

Area of Science:

• Optical Metrology
• Nanoscale Imaging
• Semiconductor Manufacturing

Background:

• Optical microscopy is crucial for analyzing nanoscale features and defects.
• Upcoming sub-20 nm semiconductor device dimensions challenge current defect detection methods.
• Optimizing scattered electromagnetic fields from sub-wavelength structures is key for metrology.

Purpose of the Study:

• To present a novel volumetric analysis for processing focus-resolved images of defects.
• To demonstrate the capability of revealing sub-20 nm defects with high sensitivity.
• To compare the sensitivity of 2D and 3D imaging techniques for defect analysis.

Main Methods:

• Development of a novel volumetric analysis technique for focus-resolved defect imaging.
• Utilizing simulated and experimental data for validation.
• Optimization of focus and illumination conditions for 3D data analysis with 193 nm light.

Main Results:

• Successfully revealed defects as narrow as (16 ± 2) nm (k = 1).
• Demonstrated the effectiveness of the new method for sub-20 nm defect detection.
• Quantitative metrics indicated potential fourfold improvements in sensitivity compared to 2D imaging.

Conclusions:

• The novel volumetric analysis offers enhanced sensitivity for nanoscale defect detection in semiconductor patterning.
• This method addresses the limitations of current optical techniques for future sub-20 nm devices.
• 3D data analysis provides significant advantages over traditional 2D imaging for metrology.