Light scatter from polysilicon and aluminum surfaces and comparison with surface-roughness statistics by atomic force...

Area of Science:

• Materials Science
• Optical Engineering
• Surface Science

Background:

• Surface roughness significantly influences optical scatter.
• Accurate characterization of surface topography is crucial for predicting optical properties.

Purpose of the Study:

• To compare optical scatter measurements with surface statistics derived from atomic force microscopy.
• To evaluate the validity of angle-resolved-scattering theory for polysilicon and aluminum surfaces.

Main Methods:

• Optical scatter measurements using 632.8-nm and 488-nm illumination.
• Surface topography analysis via atomic force microscopy (AFM).
• Calculation of scatter predictions using power spectral density (PSD) and scattering theory.

Main Results:

• Fair agreement between measured scatter and theoretical predictions for polysilicon (18, 42 nm rms roughness) and aluminum (17 nm rms roughness).
• Poor agreement for other samples, suggesting limitations in the measurement or model.
• Internal scatter within the measuring instrument identified as a primary source of discrepancy.

Conclusions:

• Angle-resolved-scattering theory provides a reasonable approximation for certain surface roughness regimes.
• Instrumental limitations, specifically internal scatter, can significantly affect the accuracy of optical scatter measurements.
• Further refinement of measurement techniques and theoretical models is needed for precise surface characterization.