13 March 2012 New methodology to predict pattern collapse for 14nm and beyond
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Critical aspect ratio induced pattern collapse has been a concern for lithography process engineers since before the 180 nm node. This line bending can lead to pattern deformation or complete substrate adhesion failure. Several process improvements, such as surfactant-laced final rinse, have been proposed to alter surface energies and increase the critical aspect ratio for collapse. The challenge is more severe for sub-60 nm pitch ground-rules that are being developed for the 14 nm technology node, since 30nm and smaller spaces will produce extremely large capillary forces acting on very narrow resist patterns. In previous studies, an analytical model was used to predict pattern collapse of simplified line/space structures. In this work, we propose a new framework to predict pattern collapse of sub-60 nm pitch EUV resist structures by the use of a semi-empirical model. This semi-empirical model is derived from the one-dimensional analytical model, which includes a term dependent on the local pattern geometry and the physical properties of the resist and rinse solution. We calibrate/verify the model with various EUV pattern collapse data collected from onedimensional (e.g., line/space) patterns. Hotspots predicted by the semi-empirical model are compared with those obtained from EUV wafer exposures. Weaknesses in model prediction were then used to adjust the model terms. Determining pattern collapse and identifying hot-spots early in the development cycle is critical for setting restricted design rules and refining DFM/RET solutions.
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Aasutosh Dave, Aasutosh Dave, Kenji Yoshimoto, Kenji Yoshimoto, John Sturtevant, John Sturtevant, } "New methodology to predict pattern collapse for 14nm and beyond", Proc. SPIE 8326, Optical Microlithography XXV, 83261K (13 March 2012); doi: 10.1117/12.917885; https://doi.org/10.1117/12.917885


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