surface roughness measurement

Surface Roughness Measurement in semiconductor manufacturing is the quantitative characterization of surface height variations at various spatial scales — using a combination of optical and contact methods to measure roughness from atomic scale (Angstroms) to millimeter scale across different frequency bands.

Measurement Techniques

• AFM: Atomic Force Microscopy — scans a sharp tip across the surface, measuring nm-scale height variations.
• Optical Profilometry: White-light interferometry or confocal microscopy — fast, non-contact, µm resolution.
• Scatterometry: Light scattering from surface roughness — integrating measurement over large areas.
• Haze Measurement: Diffuse light scattering on wafer inspection tools — qualitative roughness proxy.

Why It Matters

• Process Window: Surface roughness affects lithographic focus, film adhesion, etch uniformity, and device performance.
• Multi-Scale: Different process steps are affected by different roughness wavelengths — multi-scale characterization is essential.
• Specifications: Each process layer has roughness specifications — incoming wafers, post-CMP, post-etch, post-clean.

Surface Roughness Measurement is mapping the microscopic terrain — quantifying surface texture at every relevant scale with the appropriate metrology tool.