Abstract: The present invention is a hybrid technique for finding defects on digitized device images using a combination of spatial domain and frequency domain techniques. The two dimensional spectra of two images are found using Fourier like transforms. Any strong harmonics in the spectra are removed, using the same spectral filter on both spectra. The images are then aligned, transformed back to the spatial domain, and subtracted. The resulting spectrally-filtered difference image is thresholded and analyzed for defects. Use of the hybrid technique of the present invention to process digitized images results in the highest-performance and most flexible defect detection system. It is the best performer on both array and random devices, and it can cope with problems such as shading variations and the dark-bright problem that no other technique can address.

Abstract: A process and apparatus for qualifying a reticle, master pattern, or the like, in-situ as it is used in a system for photolithographically creating an image on a substrate, including the steps of coating a transparent substrate with a layer of transparent photoresist material, placing the coated substrate with a layer of transparent photoresist material, placing the coated substrate on a substrate supporting means, using a source of illumination in combination with a reticle, or master pattern, to create an image of the reticle, or master pattern, on the substrate, thereby exposing the photo resist coated on the surface thereof, removing the substrate from the supporting means, developing the exposed photoresist to produce a transparent patterned mask on the surface of the substrate, said patterned mask corresponding to the pattern on the reticle, or master pattern, and, in combination with the substrate, forming a monitor object, inspecting the monitor object by passing light through both the transparent mas