A classification scheme for visual defects arising in semiconductor wafer inspection

Abstract

In this paper we describe a novel scheme to characterize surface defects and flaws that arise in semiconductor wafer processing. This is done by analyzing the texture of an image of the defect. We have developed a taxonomy for textures, which classifies textures into the broad classes of disordered, strongly ordered and weakly ordered. Disordered textures are described in terms of their fractal dimension, strongly ordered textures are by the placement of primitives, and weakly ordered textures by the underlying orientation field. We have developed an algorithm to measure the fractal dimension of a given texture. We use the qualitative theory of differential equations to devise a symbol set for the weakly ordered textures in terms of singularities. We have devised an algorithm to process an image of a defect and extract qualitative descriptions based on this theory.