Patent ID: 7295695

Claim:
A method of detecting a defect in a reticle or wafer, the method comprising: obtaining a first image of a portion of the wafer or reticle and a second image of a portion of a same or different wafer or reticle or rendered from a design database file corresponding to a portion of a same or different wafer or reticle; obtaining a wavelet transform of a difference between the first image and the second image; filtering the wavelet transformed image of the difference between the first image and the second image so as to substantially eliminate portions of the wavelet transformed image that contain pattern and/or random noise and so as to substantially retain portions of the wavelet transformed image that correspond to real defect differences between the wafer or reticle portions; producing an inverse wavelet transform of the filtered image; and determining whether there is a defect in the first or second image based on the inverse wavelet transformed image whereby it is determined that there is a defect when the inverse wavelet transformed image corresponds to a real defect difference between the reticle or wafer portions.