Angle-Resolved Scatterometry is a variant of optical scatterometry that measures the diffraction signature as a function of incidence angle — varying the angle of the incoming light beam and measuring the reflected/diffracted intensity at each angle to extract structural parameters of periodic features.

Angle-Resolved Approach

• Fixed Wavelength: Typically uses a single wavelength (e.g., 633nm HeNe laser) at multiple incidence angles.
• θ-2θ Scan: Vary both incidence and detection angles — measure the angular distribution of scattered light.
• Signature: The angular reflectance curve is the "fingerprint" of the structure's geometry.
• Measurement Types: Specular reflectance vs. angle, or specific diffraction order intensity vs. angle.

Why It Matters

• Complementary: Angle-resolved data provides different sensitivity than spectroscopic (wavelength-varying) data.
• Robust: Combining angle and wavelength variation (hybrid approach) improves parameter extraction accuracy.
• Overlay: Critical for diffraction-based overlay (DBO) measurement — first diffraction order intensity vs. angle.

Angle-Resolved Scatterometry is reading the angular fingerprint — extracting structural dimensions from the angle-dependent diffraction signature of periodic features.