Impact of Process-Effect Correction Strategies on Variability of Critical Dimension and Electrical Characteristics in Extreme Ultraviolet Lithography

Abstract

The conventional correction strategy used to compensate for imaging errors in extreme ultraviolet (EUV) lithography is accomplished by incorporating independent corrections in which rule-based corrections are used to compensate for EUV-specific imaging effects such as mask shadowing, and a model-based correction is used to compensate for proximity effects. Because most rule-based corrections are empirically developed by using simple Manhattan patterns, some of the simplified approximation approaches would not be applicable in a circuit layout with complicated geometric patterns. These kinds of approximation approaches can lead to ineffective corrections of EUV-specific imaging effects, resulting in inaccurate patterns printed on a wafer which will significantly alter the electrical characteristics of fabricated circuits. In order to prevent the problems due to rule-based corrections, a promising correction strategy has been proposed to simultaneously deal with EUV-specific imaging effects and proximity effects. In this study, the impact of two different correction strategies on the critical dimension (CD) variation caused by defocus and the deviation of electrical characteristics from the design intent is explored. Numerical experiments indicate that the variability of CD and electrical characteristics is significantly improved by the proposed correction strategy.