Automated measurement and analysis of sidewall roughness using three-dimensional atomic force microscopy

Area of Science:

• Materials Science
• Nanotechnology
• Metrology

Background:

• Semiconductor device architecture is evolving towards 3D structures like FinFET and Gate-All-Around (GAA).
• Precise measurement of 3D structure sidewalls is critical for advanced semiconductor manufacturing.
• Existing metrology tools face challenges in accurately assessing sidewall roughness (SWR) in complex 3D geometries.

Purpose of the Study:

• To introduce a novel 3-Dimensional Atomic Force Microscope (3D-AFM) for precise 3D metrology.
• To demonstrate the capability of 3D-AFM in measuring sidewall roughness (SWR) of vertical and undercut structures.
• To validate the reproducibility and wafer-level distribution analysis of the 3D-AFM system.

Main Methods:

• Development and application of a 3-Dimensional Atomic Force Microscope (3D-AFM) utilizing a tilted Z scanner.
• Repeated measurements on three distinct dies to assess die-level reproducibility.
• Analysis of 13 dies, including wafer center and edge positions, for wafer-level SWR distribution.
• Implementation of a novel algorithm for auto flattening, sidewall detection, and SWR calculation.
• Development of automated SWR analysis software to enhance efficiency and standardization.

Main Results:

• Achieved high reproducibility in die-level measurements with a relative standard deviation under 2%.
• Successfully analyzed SWR distribution across the wafer, demonstrating reliable measurement capabilities.
• The novel algorithm and automated software significantly reduced analysis time and standardized the process.

Conclusions:

• The presented 3D-AFM is a powerful tool for precise 3D metrology of semiconductor structures.
• The system demonstrates excellent reproducibility and wafer-level analysis capabilities for sidewall roughness.
• This technology enables an advanced, automated methodology for 3D measurement and analysis in semiconductor manufacturing.