Critical Dimension Uniformity (CDU)

Wafer-Scale CD Control & Zernike Decomposition

1.8 nm
CDU (3σ/mean)
1.2 nm
Radial Component
1.1 nm
Random Component
0.8 nm
Scanner Matching
Key Physics Equations:
CDU = 3σ/mean × 100%
Radial: CD(r) = a₀ + a₁r + a₂r² + a₃r³
Zernike: CD(ρ,θ) = Σ Zⁿₘ Rⁿₘ(ρ) cos(mθ)
Dose contribution: σ_dose = (∂CD/∂E) × σ_E
Total: σ²_total = σ²_systematic + σ²_random

Uniformity Parameters

Mean CD (nm)50
Radial σ (nm)1.5
Random σ (nm)1.0
Dose Non-Uniformity (%)2.0
Lens Aberration (mλ)25
Scanner Tilt (°)0.05
Chuck Temp (°C)22
Edge Exclusion (mm)2

1. 2D Wafer CD Map

2. Radial CD Profile

3. CDU Distribution Histogram

4. Zernike Decomposition

5. Systematic vs Random Variance

6. Scanner-to-Scanner Matching

7. CD vs Position Cross-Wafer

3D Wafer CD Map