Inorganic antireflective coating process for deep-UV lithography

Qizhi He; Wei W. Lee; Maureen A. Hanratty; Daty Rogers; Guoqiang Xing; Abha Singh; Eden Zielinski

doi:10.1117/12.310763

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29 June 1998 Inorganic antireflective coating process for deep-UV lithography

Qizhi He, Wei W. Lee, Maureen A. Hanratty, Daty Rogers, Guoqiang Xing, Abha Singh, Eden Zielinski

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Proceedings Volume 3334, Optical Microlithography XI; (1998) https://doi.org/10.1117/12.310763
Event: 23rd Annual International Symposium on Microlithography, 1998, Santa Clara, CA, United States

Abstract

Antireflective coatings (ARCs) have been used to enhance IC lithography for years, however, many conventional bottom ARCs can no longer maintain acceptable linewidth control, cannot meet stringent deep-UV (DUV) photoresist processing requirements, and increase the etch complexity. In this paper, we report the development of an inorganic ARC for DUV lithography in sub-0.25 micrometer advanced device applications. Plasma-enhanced chemical vapor deposition (PECVD) is employed to deposit a dielectric film silicon oxynitride (Si_xO_yN_z) with specific optical properties. The three optical parameters of the Si_xO_yN_z film: refractive index n, extinction coefficient k, and thickness d are specifically designed to ensure that the reflection light that passes through the ARC/substrate is equal in amplitude and opposite in phase to the reflected light from the resist/ARC interface. The reflection light is canceled by destructive interference and therefore photoresist receives the minimum substrate reflection wave. Using this technique, we have successfully patterned features at 0.25 micrometer and below. The dielectric film can not only function as an ARC layer, but also serve as a hardmask for the pattern transfer etch process. With an aggressive etch bias process, linewidths down to 0.60 micrometer poly-Si gate are achieved with good linewidth control (3(sigma) less than 12 nm) and a near perfect linearity. For the marginal metal etch resistance of DUV photoresist, the designed Si_xO_yN_z is effective in imparting more etch resistance and suppressing metal substrate reflection. Excellent optical uniformity of the n, k and thickness d of the Si_xO_yN_z ARC is obtained with a manufacturable PECVD deposition process.

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Qizhi He, Wei W. Lee, Maureen A. Hanratty, Daty Rogers, Guoqiang Xing, Abha Singh, and Eden Zielinski "Inorganic antireflective coating process for deep-UV lithography", Proc. SPIE 3334, Optical Microlithography XI, (29 June 1998); https://doi.org/10.1117/12.310763

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