Abstract
In this paper, we demonstrate a fabrication process for large area (2 mm × 2 mm) fishnet metamaterial structures for near IR wavelengths. This process involves: (a) defining a sacrificial Si template structure onto a quartz wafer using deep-UV lithography and a dry etching process (b) deposition of a stack of Au-SiO2-Au layers and (c) a ‘lift-off’ process which removes the sacrificial template structure to yield the fishnet structure. The fabrication steps in this process are compatible with today’s CMOS technology making it eminently well suited for batch fabrication. Also, depending on area of the exposure mask available for patterning the template structure, this fabrication process can potentially lead to optical metamaterials spanning across wafer-size areas.
Highlights
After Veselago put forth the idea of a left-handed medium [1], where negative permittivity and permeability values could lead to a negative refractive index, a lot of research has been conducted to realize metamaterials which exhibit negative refraction at various frequency ranges [2,3,4].In recent years optical metamaterials of various configurations have garnered a lot of attention
[16], we demonstrated a deep-UV (DUV) lithography [17] based fabrication process for optical metamaterials that was suitable for mass fabrication of optical fishnet metamaterial devices over potentially wafer-size areas
The key advantage of the fabrication process lies in the fact that the DUV lithography process used to define the template structure allows for optical metamaterials that can span across very large areas. This fabrication process, unlike e-beam lithography (EBL) and nano-imprint lithography (NIL), uses processes which are compatible with existing CMOS technology and can be implemented for mass production of these devices
Summary
After Veselago put forth the idea of a left-handed medium [1], where negative permittivity and permeability values could lead to a negative refractive index, a lot of research has been conducted to realize metamaterials which exhibit negative refraction at various frequency ranges [2,3,4]. The tendency of Au nano-particles to aggregate together and stick onto metallic surfaces [19] can result in the materials removed with the sacrificial template „lift-off‟ process to redeposit on top of the device structure This problem was not faced in our previous study due to the fact that the final BOE etch could be carried out within a sonicator, and partially due to smaller sample sizes. The key advantage of the fabrication process lies in the fact that the DUV lithography process used to define the template structure allows for optical metamaterials that can span across very large areas This fabrication process, unlike EBL and NIL, uses processes which are compatible with existing CMOS technology and can be implemented for mass production of these devices
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