Optimization of zero-reference grating considering tip distortions for scanning probe microscopy drift measurement.

Area of Science:

• Materials Science
• Metrology
• Nanotechnology

Background:

• Scanning Probe Microscopy (SPM) requires precise drift measurements for accurate nanoscale analysis.
• Nonperiodic gratings, specifically zero-reference gratings (ZRGs), offer a calibration method for SPM drift.
• Understanding the impact of tip distortions on ZRG performance is crucial for optimizing their design.

Purpose of the Study:

• To optimize zero-reference grating (ZRG) structures for scanning probe microscopy (SPM) drift measurements.
• To investigate the influence of tip distortions on ZRG performance and identify robust designs.
• To provide design guidelines for ZRGs used in quantitative drift measurements.

Main Methods:

• Utilized mathematical morphology and genetic algorithms to optimize ZRG structures.
• Analyzed the relationship between ZRG parameters (t, n, D) and tip radius.
• Interpreted results based on the effective code mechanism influenced by tip dilation.

Main Results:

• Optimal ZRG structures distribute step elements orderly with larger tip radii.
• Correlation peak contrast (D) decreases with increasing tip radius when t ≤ n/2.
• ZRG structures and contrast (D) are insensitive to tip distortions when t > n/2.

Conclusions:

• ZRGs with more than half step elements (t > n/2) exhibit robust performance against tip distortions.
• The effective code mechanism explains the reduced sensitivity to tip dilation in optimal ZRGs.
• Designing ZRGs with t > n/2 is recommended for quantitative SPM drift measurements due to enhanced robustness.