Parameter measurement using multi-layer structures

Abstract

Various embodiments disclosed herein include methods for measuring a parameter associated with a workpiece. Such a method may include providing a first overlay pattern on the workpiece and a second overlay pattern over the first overlay pattern. The first overlay pattern may comprise a first plurality of features spaced apart from each other, and the second overlay pattern may comprise a second plurality of substantially optically transmissive features spaced apart from each other. The second plurality of features may be offset with respect to and partially overlapping the first plurality of features. The method may further comprise directing light onto the first and second overlay pattern such that the light is reflected from both the first and second overlay patterns and using reflectometry to obtain a measure of the parameter from the reflected light.

Dependencies are inferred from the claim text.