Thermal nanoimprint lithography using fluoropolymer mold

• Published in: Microelectronic engineering Vol. 98; pp. 246 - 249
• Main Authors: Con, Celal, Zhang, Jian, Jahed, Zeinab, Tsui, Ting Y., Yavuz, Mustafa, Cui, Bo
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-10-2012; Elsevier
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Elasticity, elastic constants; Elasticity. Plasticity; Electronics; Exact sciences and technology; Fluoropolymer; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Mechanical properties of solids; Metals. Metallurgy; Methods of nanofabrication; Microelectronic fabrication (materials and surfaces technology); Mold; Nanofabrication; Nanoimprint lithography; Nanoscale pattern formation; Perfluoropolyether; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Soft lithography; Soft lithography; Perfluoropolyether; Nanofabrication; Nanoimprint lithography; Fluoropolymer; Mold; Dimethylsiloxane polymer; Elastic modulus; High resolution; Heat treatment; Fluorine containing polymer; Nanoindentation; Roughness; Nanostructure; Nanolithography; Casting; Microelectronic fabrication; Wire bonding; Resist; Nanotechnology
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2012.07.007

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► We studied perfluoropolyether (PFPE) as the mold material for thermal nanoimprint. ► The PFPE-based mold was fabricated from a master by casting and thermal-curing. ► It is capable of resolution far better than 100nm. ► Its elastic modulus obtained by nanoindentation is two orders higher than PDMS. ► The surface of the PFPE-based film is much stiffer and harder than the bulk.
We studied the properties of a fluoropolymer based on perfluoropolyether (PFPE) as the mold material for thermal nanoimprint lithography. The PFPE mold was duplicated from a hard master mold by casting and thermal-curing of the PFPE pre-polymer mixture. The PFPE mold was able to pattern 100nm half-pitch grating into a resist, with the very fine line edge roughness of the master mold faithfully duplicated into the resist. This implies PFPE is capable of a resolution far beyond 100nm, which is consistent with its high elastic modulus (two orders higher than PDMS) extracted from nanoindentation experiment. It was found that the elastic modulus is much higher near the film surface than deep inside the film. This is a very desirable property for an imprint mold, as the relatively stiff top surface offers high resolution, whereas the more flexible bulk is important for a conformal contact with the substrate and easy demolding.