Power Special Density (PSD)

Together with the line edge roughness (3*σ) or contact edge roughness (3*σ), two other important parameters, the correlation length (ξ) and the roughness exponent (H), can also be calculated from its power spectral density.

The graph on the left plots the PSD of left edges (the odd numbered edges).

PSD of Left Edges

PSD of Right Edges

Or both

The calculation

The power spectral frequency is defined as the square of the magnitude of the Fourier transform of the edge residuals.

PSDi (f)

= ∫-∞∞∆xije-i2πfxdx2,


using Fast Fourier Transform (FFT)

(under construction)