Modeling and calibration of resist processes in photolithography

Research in this dissertation is to model resist recording processes from imaging to resist on wafer of both continuous and microscopic scales by developing new models as well as designing super sensitive test patterns for model calibration. An enhanced simulation platform---STORM-II is first developed to carry out the study of quantitative resist modeling in this dissertation. With an improved finite element implementation, STORM-II improves computation speed by a factor of 4∼9 compared with the previous version.; State-dependent acid diffusion during post-exposure bake (PEB) is investigated with the help of a new insight to the preferential effect of acid transportation. Based on this new insight, three resist structures being sensitive to diffusion type are employed to characterize acid diffusion, which are sequentially double exposed cross, standing waves and double exposed sharp tip (DEST). Two chemically-amplified resists (CARS)---IBM APEX-E and Shipley UV210 are examined and acid transportation is found to be retarded by resist reaction in both resists resulting in reduced non-Fickian acid diffusion.; In this dissertation, DEST has been applied to enhance by one order of magnitude the sensitivity of resist profile to material phenomena. DEST has been successfully employed to visualize and calibrate acid contamination, quencher surface loss and to monitor minor fluctuation of process conditions. A fundamental tradeoff between resist resolution and resist blur is illustrated through correlating the radius of the DEST tip (the smallest printed feature) with imaging non-uniformity (standing waves).; The research of quencher effect begins with an in-depth study of a new acid-equilibrium-quencher (AEQ) modeling that is first proposed by Dr. Nagahara. Quencher study is conducted through interpreting resist reaction kinetics of both a weak acid KrF model resist and a strong acid ArF model resist over a variety of quencher loadings and exposure conditions. First and strong evidence of acid buffering effect is shown in the KrF model resist. Two different quencher mechanisms of both with and without acid buffering effect are found to exist depending on different acid strength.; In addition to quantifying macroscopic CD, line-edge roughness as statistical CD variation is also investigated leading to the development of continuous-based LER modeling strategy. This new approach is able to evaluate the effects of process conditions on LER formation without numerical complexity and has been applied to analyze LER generation as influenced by shot noise, flare and non-Fickian acid diffusion. A stress/strain induced crack propagation LER model is proposed to understand the mysterious large correlation distance in LER. (Abstract shortened by UMI.)...