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26 March 2008 Graded spin-on organic bottom antireflective coating for high NA lithography
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Immersion lithography for the 32nm node and beyond requires advanced methods to control 193 nm radiation reflected at the resist/BARC interface, due to the high incident angles that are verified under high numerical aperture (NA) imaging conditions. Swing curve effects are exacerbated in the high NA regime, especially when highly reflective substrates are used, and lead to critical dimension (CD) control problems. BARC reflectivity control is also particularly critical when underlying surface topography is present in buried layers due to potential reflective notching problems. In this work, a graded spin-on organic BARC was developed to enable appropriate reflectivity control under those conditions. The graded BARC consists of two optically distinct polymers that are completely miscible in the casting solution. Upon film coating and post-apply baking, the two polymers vertically phase-separate to form an optically graded layer. Different characterization techniques have been applied to the study of the distribution of graded BARC components to reveal the internal and surface composition of the optically graded film, which includes Variable Angle Spectroscopic Ellipsometry (VASE) and Secondary Ion Mass Spectroscopy (SIMS). Also, optical constant optimization, substrate compatibility, patterning defectivity and etch feasibility for graded BARC layers are described. Superior 193 nm lithographic performance and reflectivity control of graded BARC beyond 1.20 NA compared to conventional BARCs is also demonstrated.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dario L. Goldfarb, Sean D. Burns, Libor Vyklicky, Dirk Pfeiffer, Anthony Lisi, Karen Petrillo, John Arnold, Daniel P. Sanders, Aleksandra Clancy, Robert N. Lang, Robert D. Allen, David R. Medeiros, Dah Chung Owe-Yang, Kazumi Noda, Seiichiro Tachibana, and Shozo Shirai "Graded spin-on organic bottom antireflective coating for high NA lithography", Proc. SPIE 6923, Advances in Resist Materials and Processing Technology XXV, 69230V (26 March 2008);

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