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26 March 2019 Unraveling the EUV photoresist reactions: which, how much, and how do they relate to printing performance
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The interaction of 91.6eV EUV photons with photoresist is very different than in optical lithography at DUV wavelength. The latter is understood well, and it is known that photons interact with the resist on molecular level: e.g. for chemically amplified resist (CAR) the photon interacts with the photo acid generator (PAG), which leads to a deprotection reaction on a polymer. At EUV however, the high energy photons interact with the matter on the atomic scale, resulting in the generation of secondary electrons, which in turn induce chemical modification at lower energies. Although the complex detailed EUV mechanisms that lead to a chemical reaction in CAR are still not fully understood, we have developed and optimized an alternative technique to measure the reactions. The technique is based on Residual Gas Analysis (RGA) and enables to reveal the chemical identity of outgassed reaction products, therefore it can give information on the ongoing reactions during EUV exposure. In this work, we used this technique in a feasibility study to investigate how the balance of CAR resist reactions related to solubility and insolubility can impact the resist stochastic failure. This has first been applied on a model resist to characterize what the relevant reactions are for the solubility of the CAR. The method enabled to quantify the CAR acid yield and the (EUV specific) reactions that can lead to insolubility as function of dose. Based on the understanding of the ongoing reactions, the methodology has been applied on a family of resists – centered on a commercial resist – formulated on one polymer type but with different PAG/quencher. All these materials have been tested towards the balance of solubility reactions as function of dose and towards stochastic failures. A tentative correlation was found between the measurement of the stochastic failures and a semi-empirical equation of the RGA based resist parameters related to solubility.
Conference Presentation
© (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ivan Pollentier, John S. Petersen, Peter De Bisschop, Danilo De Simone, and Geert Vandenberghe "Unraveling the EUV photoresist reactions: which, how much, and how do they relate to printing performance", Proc. SPIE 10957, Extreme Ultraviolet (EUV) Lithography X, 109570I (26 March 2019);

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