Method for Detection and Location of Defects in Integrated Circuits
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
It is important to be able to rapidly inspect and observe the location of defects, particle contaminants, or other imperfections in integrated circuits. When inspections of these circuits are performed under a microscope or through an optical system, there are often many features present which make it difficult to observe defects or imperfections in structures. For example, it is difficult to sense small variations produced by defects when they are masked by the contrast of the perfect circuit structure. In order to avoid this masking problem, low-pass filtering is used in the optical imaging system. (Image Omitted) The images of periodic or repeating circuit elements are eliminated by placing a small aperture in the backfocal plane of the image-forming lens.