Substrate effect on CD Control for Ion Implantation Layer Lithography Beyond 45 nm Node

Abstract

Implant level photolithography processes are becoming more and more challenging due to decreasing CD and photoresist edge placement requirements. In addition to the traditional proximity effects associated with the implant layer mask, the underlying active and gate layers can interact through a variety of mechanisms to influence the edge placement of the developed implant layer. For many implant layers, the impact of underlying topography cannot be subdued, because, because it is not desirable to employ bottom anti-reflection coating (BARC) for various reasons. Therefore, the implant OPC models calibrated on bare silicon wafers must include additional compensation components to counter the various substrate complexities from real device/design scenarios. In this paper, we show our systematic study on substrate effect (AA/STI) on implant level lithography CD printing including real wafer data analysis and simulation with wafer 3D OPC. Besides, we also show some study of the poly effect on CD. Based on the results, we generate an empirical model to match the substrate effect, and also proposed an approach with additional substrate-aware OPC rule to correct such effect.