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Overlay measurement using angular scatterometer for the capability of integrated metrology.
Optics Express
|June 12, 2009
Summary
Angular scatterometry offers precise overlay metrology by analyzing light scattered from gratings. This optical technique simultaneously determines overlay, critical dimension, and sidewall angle, showing potential for integrated metrology.
Area of Science:
- Optical Metrology
- Semiconductor Manufacturing
Background:
- Overlay metrology is crucial for semiconductor manufacturing.
- Existing methods face challenges in precision and integration.
Purpose of the Study:
- To evaluate angular scatterometry as an alternative for precise overlay metrology.
- To assess its capability for simultaneous measurement of multiple structure parameters.
Main Methods:
- Utilized an angular scatterometer and bright-field microscope for overlay measurements.
- Developed a theoretical library using rigorous coupled wave theory.
- Matched measured reflected signatures to the library for parameter extraction.
Main Results:
- Angular scatterometry demonstrated high precision in overlay measurements.
- Achieved low tool-induced shift, indicating measurement stability.
- Successfully obtained overlay, critical dimension (CD), and sidewall angle simultaneously.
Conclusions:
- Angular scatterometry is a precise and viable technique for overlay metrology.
- The method shows significant potential for integrated metrology in semiconductor fabrication.
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