Overlay Metrology & APC

Layer Alignment & Process Control

1.5 nm
RMS Overlay
2.0 nm
Translation Error
0.5 ppm
Magnification
5 μrad
Rotation
Key Physics Equations:
Overlay: Δx = x_measured - x_designed
Model: Δx = T_x + S_x·x + S_y·y + R·y + M_x·x²
Zernike: Δ(ρ,θ) = Σ c_nm Z_nm(ρ,θ)
Wafer Grid: minimize RMS(Δx² + Δy²)
APC Correction: x_new = x_old - K × error

Overlay Parameters

Translation X (nm)5
Translation Y (nm)3
Magnification (ppm)2
Rotation (μrad)8
Orthogonality (nm/mm)2
Asymmetric Mag (ppm)1.5
Higher Order (nm)1
Mark Quality (%)85

1. Overlay Vector Map

2. Overlay Magnitude Heatmap

3. Zernike Coefficients

4. Overlay Error Tree

5. Residuals After Correction

6. APC Performance Over Time

7. Scanner Matching

3D Overlay Field