11 December 2009 Image reversal trilayer materials and processing
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Proceedings Volume 7520, Lithography Asia 2009; 75200L (2009) https://doi.org/10.1117/12.837017
Event: SPIE Lithography Asia, 2009, Taipei, Taiwan
Image reversal trilayer (IRT) combines three lithographic patterning enhancement approaches: image reversal, spin on hard masks, and shrink for recess types of features. With IRT, photoresist imaging is done directly on top of the carbon underlayer. Thick IRT-Carbon Hard Masks (CHM) films provide effective antireflection with high NA lithography and are more etch resistant than common photoresist. IRT-Silicon Hard Masks (SiHM) can be coated over the resist patterns in the lithography track. IRT etching reverses the resist pattern into the IRT-SiHM and transfers this image to the IRTCHM. The recessed patterns in the IRT-CHM are smaller than the CD of the photoresist feature from an inherent shrinking capability of the IRT-SiHM. Continuous improvements to both IRT-SiHM and IRT-CHM have been made. Silicon contents in IRT-SiHM have been pushed as high as possible while not impacting other important properties such as stability, coating quality and resist compatibility. Newer polysiloxane IRT-SiHM no longer require resist freezing prior to coating. Carbon contents in IRTCHM have been pushed as high as possible while maintaining solubility and a low absorption which is important when resist imaging is done directly on top of the IRT-CHM. Feasibility of this image reversal trilayer process was previously demonstrated on L/S and pillar gratings. Recent work focused on nonsymmetrical 2D gratings and simultaneous patterning of L/S gratings at different pattern densities. Particular emphasis is given to pattern density effects which are applicable to any top-coating image reversal process. This paper describes the lithography, pattern transfer process and 2nd generation hard mask materials developed for IRT processing.
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David J. Abdallah, David J. Abdallah, Kazunori Kurosawa, Kazunori Kurosawa, Elizabeth Wolfer, Elizabeth Wolfer, Victor Monreal, Victor Monreal, M. Dalil Rahman, M. Dalil Rahman, DongKwan Lee, DongKwan Lee, Mark Neisser, Mark Neisser, Ralph R. Dammel, Ralph R. Dammel, } "Image reversal trilayer materials and processing", Proc. SPIE 7520, Lithography Asia 2009, 75200L (11 December 2009); doi: 10.1117/12.837017; https://doi.org/10.1117/12.837017

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