Sensitizers in extreme ultraviolet chemically amplified resists: mechanism of sensitivity improvement

Yannick Vesters; Jing Jiang; Hiroki Yamamoto; Danilo De Simone; Takahiro Kozawa; Stefan De Gendt; Geert Vandenberghe

doi:10.1117/1.JMM.17.4.043506

12 December 2018 Sensitizers in extreme ultraviolet chemically amplified resists: mechanism of sensitivity improvement

Yannick Vesters, Jing Jiang, Hiroki Yamamoto, Danilo De Simone, Takahiro Kozawa, Stefan De Gendt, Geert Vandenberghe

Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 17, Issue 4, 043506 (December 2018). https://doi.org/10.1117/1.JMM.17.4.043506

Abstract

Extreme ultraviolet (EUV) lithography utilizes photons with 92 eV energy to ionize resists, generate secondary electrons, and enable electron driven reactions that produce acid in chemically amplified photoresists. Efficiently using the available photons is of key importance. To increase photon absorption, sensitizer molecules, containing highly absorbing elements, can be added to photoresist formulations. These sensitizers have gained growing attention in recent years, showing significant sensitivity improvement. Aside from an increasing absorption, adding metal salts into the resist formulation can induce other mechanisms, like higher secondary electron generation or acid yield, or modification of the dissolution rate that also can affect patterning performance. In this work, we used different sensitizers in chemically amplified resists. We measured experimentally the absorption of EUV light, the acid yield, the photoelectron emission, the dissolution rate, and the patterning performance of the resists. Addition of a sensitizer raised the acid yield even though a decrease in film absorbance occurred, suggesting an apparent increase in chemically resonant secondary electrons. While patterning results confirm a significant sensitivity improvement, it was at the cost of roughness degradation at higher sensitizer loading. This is hypothesized by the chemical distribution of the sensitizer in the resist combined with a modification of the dissolution contrast, as observed by dissolution rate monitor measurements.

Citation Download Citation

Yannick Vesters, Jing Jiang, Hiroki Yamamoto, Danilo De Simone, Takahiro Kozawa, Stefan De Gendt, and Geert Vandenberghe "Sensitizers in extreme ultraviolet chemically amplified resists: mechanism of sensitivity improvement," Journal of Micro/Nanolithography, MEMS, and MOEMS 17(4), 043506 (12 December 2018). https://doi.org/10.1117/1.JMM.17.4.043506

Received: 21 June 2018; Accepted: 14 November 2018; Published: 12 December 2018

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