Development of an optimal inspection strategy for chemical mechanical polished (CMP) wafers

Abstract

Summary form only given. This paper details the path taken to develop an optimal inspection strategy for monitoring defect levels from a CMP process. The relative unpredictability of this process can cause thickness variations across a wafer. These variations make many conventional inspection techniques unreliable. The objective of this study is to analyze the validity of using: current inspection techniques, such as laser scattering and image processing tools; new inspection techniques, such as Perspective Darkfield imaging, circular polarization, low oblique laser scattering and new imaging techniques using high Numerical Aperture objectives with various magnification changers; modifications of current techniques. The results of these tests will be compiled and analyzed to determine if current inspection techniques can be used effectively within the process flow or if new inspection techniques must be incorporated.