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Linewidth measurement on IC masks and wafers by grating test patterns
Applied Optics
|March 11, 2010
Summary
This study introduces a laser diffraction method for precise linewidth measurement in integrated circuits. The technique accurately monitors grating line widths on chrome masks and silicon wafers, crucial for semiconductor manufacturing quality control.
Area of Science:
- Optics and Photonics
- Semiconductor Manufacturing
- Metrology
Background:
- Accurate linewidth measurement is critical for integrated circuit (IC) fabrication.
- Existing metrology methods may have limitations in precision or applicability across different manufacturing stages.
Purpose of the Study:
- To develop and validate a non-contact optical technique for testing and monitoring linewidths on IC structures.
- To assess the accuracy and applicability of diffraction pattern analysis for critical dimension measurements.
Main Methods:
- Utilizing test patterns in the form of diffraction gratings.
- Analyzing the first and second diffraction orders produced by a laser beam.
- Conducting measurements on chrome masks and silicon wafers at various fabrication stages.
Main Results:
- The diffraction grating technique achieves 5% accuracy for linewidths down to 0.5 micrometers on chrome masks.
- Successful testing of patterns on silicon wafers after photoresist development and etching steps.
- Demonstrated an automatic setup for rapid wafer testing.
Conclusions:
- Laser diffraction offers a precise and efficient method for linewidth metrology in semiconductor manufacturing.
- The technique is suitable for both mask inspection and direct wafer testing throughout the fabrication process.
