Improving lithography intra wafer CD for C045 implant layers using STI thickness feed forward

In this paper we performed an analysis of various data collection preformed on C045 production lots in order to assess the influence of STI oxide layers on the CD uniformity of implant photolithography layers. Our final purpose is to show whether the DOSE MAPPER TM software option for interfiled dose correction available on ASML scanners combined with a run-to-run feed-forward regulation loop could improve global CD uniformity on C045 implants layers. After a brief presentation of the C045 implants context the results of the analysis are presented : swing curves, process windows analysis, and intra-die CD measurements are presented. The conclusion of the analysis is that it is not possible, in the current C045 industrial environment, to use a robust and general method of interfield dose correction in order to achieve a better global CD uniformity.