Top-down Determination of Fluctuations in Topographic Measurements

Area of Science:

• Metrology
• Surface characterization
• Measurement uncertainty

Background:

• Traditional dimensional metrology often relies on bottom-up approaches.
• These methods require detailed knowledge of instrument transfer functions and inherent fluctuations.
• Quantifying measurement uncertainty directly from surface data is challenging.

Purpose of the Study:

• To present and validate a novel top-down method for quantifying topographic height fluctuations.
• To investigate the relationship between surface topography and measurement uncertainties.
• To demonstrate the method's applicability across diverse surface types.

Main Methods:

• A top-down methodology involving multiple, successive topographic measurements at a single location without moving the sample.
• Statistical analysis of measured height data (z = z(x,y)) at each position.
• Generation of fluctuation maps based on calculated variances.

Main Results:

• The developed method successfully quantified height fluctuations directly from surface measurements.
• Fluctuation distributions were found to be similar to topographic features, indicating topography influences uncertainty.
• Significant variations in uncertainty were observed across different surface regions and morphologies, even non-Gaussian distributions.

Conclusions:

• The top-down method provides a direct means to assess measurement uncertainty without instrument calibration.
• Surface topographic features demonstrably impact and correlate with measurement fluctuations.
• This approach enhances understanding of uncertainty sources in surface metrology, particularly for complex surfaces.