An advanced methodology for the reporting of original adders for process tool defect monitoring

With the increasing cost of bare silicon wafers, many IC manufacturers are choosing to run fewer and fewer process tool qualifications. This decision places an increasingly larger number of production wafers at risk from process tool excursions as well as an increasingly high demand on the dependability and consistency of the qualification data. In this paper, we describe our methodology of determining only original adders in process tool qualification. The importance of reporting only added defects to the process tool control chart was justified by showing a correlation between inline yield-enhancement charts and un-patterned tool qualifications. In the past, it has been very hard to correlate un-patterned charts to inline yield-limiting charts and also to final yield