Test structure for electrically measuring the degree of misalignment between successive layers of conductors

Abstract

The present invention advantageously provides a test structure and method for using electrical measurements to determine the overlay between successive layers of conductors lithographically patterned upon a semiconductor topography. According to an embodiment, a test structure is provided which includes first, second, and third conductive structures having first, second, and third corner regions, respectively. Alternatively, the conductive structures may include only a single conductive structure having three corner regions. Each corner region is bounded by a pair of outer lateral edges configured substantially perpendicular to one another. First, second, and third conductors are operably coupled to the first, second, and third corner regions, respectively, such that overlapping areas of the conductors arranged directly above the corner regions are substantially rectangular in shape. The layout design for the test structure specifies the targeted dimensions, x and y, of each overlapping area. Fabrication of the test structure may result in the overlapping areas being shifted from their targeted positions such that their dimensions are larger or smaller than their targeted values. The amount by which the overlapping areas are shifted in the x direction is known as &Dgr;x, and the amount by which the overlapping areas are shifted in the y direction is known as &Dgr;y. The contact resistances between the overlapping areas of the conductors and the corner regions may be found and substituted into equations for &Dgr;x and &Dgr;y.