Electron beam lithography for high density meta fish scale operational at optical frequency

• Published in: Microelectronic engineering Vol. 86; no. 4; pp. 1081 - 1084
• Main Authors: Chen, Yifang, Schwanecke, Alexander S., Fedotov, V.A., Khardikov, V.V., Mladyonov, P.L., Prosvirnin, S.L., Rogacheva, A.V., Zheludev, Nikolay I., Huq, Ejaz
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2009; Elsevier
• Subjects: Applied sciences; Bilayer technique; Chiral structure; Circuit properties; Electric, optical and optoelectronic circuits; Electron beam lithography; Electronics; Exact sciences and technology; Integrated optics. Optical fibers and wave guides; Lift-off; Magnetic wall; Meta fish scale; Microelectronic fabrication (materials and surfaces technology); Optical and optoelectronic circuits; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Undercut; Undercut; Lift-off; Electron beam lithography; Bilayer technique; Meta fish scale; Chiral structure; Magnetic wall; Integrated optics; High resolution; High density; Optical frequency; Lift off; Microelectronic fabrication; Wave propagation; Line width; Optical characteristic; Resist; Bilayers
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2008.11.094

This paper reports our recent progress in electron beam lithography for high resolution and highly dense metallic structures such as fish scale on both silicon and quartz. To observe photonic property in optical frequency, the pitch of 500 nm with both linewidth and gap of 50 nm gap in Al is demanded. For reliable lift-off process, adequate undercut in bilayer layer of resists is essential. Three different bilayers, PMMA/LOR, PMMA/copolymer and PMMA/PMMA (with different molecular weights) were compared and the most suitable bilayer was found to be the PMMA/PMMA with a difference in molecular weight between the top and bottom layer. With such a bilayer stack, dense fish scale pattern with minimum linewidth of 50 nm in Al were fabricated for both transparent and reflective configurations. Astonishing optical properties such as magnetic wall and asymmetric propagating waves through the chiral fish scale were observed.