Patent ID: 7649624

Claim:
A method of detecting one or more scratches on a surface of a wafer made of a non-semiconductor material, comprising: providing a UV beam from a UV illumination source; causing a UV beam to be incident on a surface of a front surface of the wafer creating a reflected beam of scattering of the UV beam in response to scratches on a surface of the wafer, the UV beam being characterized that for scratches of a given material having a UV cutoff wavelength λ cutoff , over 90% of the spectral system response SSR is at wavelengths below λ cutoff −5 nm and expressed as: ∫ 0 λ cutoff - 5 ⁢ nm ⁢ SSR ⁡ ( λ ) > 0.90 · ∫ 0 ∞ ⁢ SSR ⁡ ( λ ) ⁢ capturing the scattering from scratches with a UV camera.