Measurement of cross section of an LSI wafer by inverse stereo matching

Abstract

SUMMARYThis research paper proposes a novel method for estimating the cross-sectional shape of an LSI wafer from a stereo image of an electron microscope. Three-dimensional measurement of an LSI wafer is critical in systems that perform nondestructive dimensional measurement of integrated circuits. In this method, the secondary electron intensity is converted to a three-dimensional shape by using the relationship between the three-dimensional shape and the secondary electron intensity produced when an electron beam is directed to an LSI wafer. A three-dimensional shape can be restored with greater detail by employing an energy minimization method. As a result, the proposed method can stably restore a detailed three-dimensional shape in comparison with the conventional stereo matching method. Since the proposed method restores a three-dimensional shape using a process that is the inverse of the stereo matching method, the proposed method is called the "inverse stereo matching method," and experimental results obtained using an electron micrograph taken of the LSI wafer show the effectiveness of the proposed method.