29 March 2006 Reactive ion etching of fluorine containing photoresist
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Abstract
Photoresist are commonly used in semiconductor processing as soft masks for pattern transfer into multilayer stacks using reactive ion etching. The etch performance of the photoresist during such a process is an important consideration during resist selection. Since resist composition strongly influences it's etch performance, understanding the correlation is important for resist development as well as etch optimization. In this paper, blanket etch rate of photoresist used in ArF lithography were examined as a function of polymer structure and atomic content. In particular, the impact of Fluorine content on blanket etch rate was studied. Etch results for a diverse sample of development and commercial resists were first fitted with the Ohnishi parameter [2] and ring parameter [3] models. The Ohnishi model correlates the carbon, hydrogen and oxygen atomic content of the resist to blanket etch rate whereas the ring parameter model is based on the cyclic carbon content. Since some of the evaluated resists contained fluorine which significantly influences the etch performance, both models were found to be inadequate in assessing its impact. Thus we introduce a modified Ohnishi parameter model to help examine the relative contributions due to resist fluorine content. With the new empirical model, good fits were obtained for etch rates of a fluorine containing resists. The model also enabled analysis of the etch process to determine the relative influence of oxygen versus fluorine content in the resist on etch rate. Finally, the model was utilized to design newer etch resistant materials and the improved etch performance was verified.
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Kaushal S. Patel, Kaushal S. Patel, Victor Pham, Victor Pham, Wenjie Li, Wenjie Li, Mahmoud Khojasteh, Mahmoud Khojasteh, Pushkara Rao Varanasi, Pushkara Rao Varanasi, } "Reactive ion etching of fluorine containing photoresist", Proc. SPIE 6153, Advances in Resist Technology and Processing XXIII, 61530Q (29 March 2006); doi: 10.1117/12.656605; https://doi.org/10.1117/12.656605
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