Contribution of Polychromatic Illumination to Optical Proximity Effects in the Context of Deep-UV Lithography

摘要

In this paper, various optical proximity effects are evaluated as a function of spectral properties of excimer laser illumination. Sensitivity of linewidth biasing and line-end pullback to spectral bandwidth and its variations is investigated using computer simulations based on PROLITH software. Studies are performed for isolated and dense lines ranging in size from 150nm to 130nm using projection lens numerical aperture of 0.7 and KrF illumination. Results show that a non-linear, through-pitch critical dimension sensitivity to laser bandwidth variation introduces additional feature biasing, which can not be compensated with optical proximity correction techniques, and can result in an additional shift of the iso-dense bias. Also, line-end pullback of isolated lines exhibits a non-linear response to bandwidth resulting in up to 7nm of pullback per 0.1pm of bandwidth change.