Film thickness measurement based on nonlinear phase analysis using a Linnik microscopic white-light spectral...

Area of Science:

• Optical Metrology
• Thin Film Analysis
• Interferometry

Background:

• Accurate thin film thickness measurement is crucial in various scientific and industrial applications.
• White-light spectral interferometry (WLSI) is a powerful technique for non-contact metrology.
• Nonlinear phase components in WLSI signals can introduce significant errors in thickness measurements.

Purpose of the Study:

• To analyze and compensate for nonlinear phase components in WLSI signals for enhanced film thickness measurement.
• To develop methods for correcting errors arising from effective thickness and double-objective lenses.
• To improve the overall accuracy of thin film thickness determination using a Linnik microscopic interferometer.

Main Methods:

• Utilized a Linnik microscopic white-light spectral interferometer to capture spectral interferometric signals.
• Developed a wavelength-correction method to account for effective thickness influence.
• Proposed a novel method for extracting and removing nonlinear phase errors from double-objective lenses.

Main Results:

• Successfully identified and quantified nonlinear phase components including those from effective thickness, double-objective lens, and the thin film itself.
• Demonstrated that the proposed wavelength-correction method effectively removes nonlinear phase contributions from effective thickness.
• Showcased the effectiveness of the double-objective lens error extraction method in improving measurement precision.

Conclusions:

• The developed methods significantly enhance the accuracy of thin film thickness measurements using WLSI.
• Accurate film thickness determination is achievable by systematically removing identified nonlinear phase errors.
• This research provides a robust approach for precise metrology in thin film characterization.