<title>Alignment performance as a function of chemical mechanical polishing techniques and stepper optimization</title>

Abstract

Optimized alignment for chemical mechanical polishing has been studied in detail to ascertain the best overall overlay and process conditions. This paper describes the methodology of alignment mark design and testing in conjunction with chemical mechanical polishing optimization for technologies of O.35um and below. The planarization of the substrate material by CMP combined with asymmetric metal deposition can cause linear alignment displacement. This study investigated chemical mechanical polish slurry types, hardware configuration, and process variables on general alignment conditions. Further study on alignment mark designs and photolithography stepper settings are investigated on a subset of optimized chemical mechanical polish conditions. An alignment condition where the result of less than O.lOum(X+3 sigma) was obtained.