Rotating compensator spectroscopic ellipsometry based on frequency division multiplexing with retardation...

Area of Science:

• Materials Science
• Optical Physics
• Metrology

Background:

• Spectroscopic ellipsometry (SE) is crucial for non-destructive material characterization, including optical constants and film thickness.
• Existing SE techniques have limitations in simultaneous multi-wavelength analysis and comprehensive property extraction.

Purpose of the Study:

• To theoretically and experimentally demonstrate a novel Frequency Division Multiplexing Rotating Compensator Spectroscopic Ellipsometry (FDM-RCSE) technique.
• To enable simultaneous measurement of multiple ellipsometry transfer quantities (ETQ) at various wavelengths.

Main Methods:

• Utilized frequency division multiplexing (FDM) with a rotating compensator and retardation calibration.
• Employed lasers with multiple wavelengths and a spectrally integrating detector for simultaneous ETQ acquisition.
• Compared FDM-RCSE measurements with a commercial SE instrument for performance evaluation.

Main Results:

• FDM-RCSE successfully measured SiO2 film thicknesses on Si wafers with an average difference of less than 2 Å compared to commercial SE.
• Achieved high measurement reproducibility and enabled extraction of more comprehensive optical properties like depolarization.
• Demonstrated simultaneous measurement of three ETQs at multiple wavelengths without spectral analysis or wavelength switching.

Conclusions:

• The FDM technique is effectively applicable to ellipsometry with compensators and retardation calibration.
• FDM-RCSE provides a versatile alternative for advanced optical material characterization.
• This method enhances SE capabilities for detailed analysis of material properties.