Large area low cost manufacturing process for precision diffraction gratings with very small line-edge-roughness (LER) and defect-free surface coverin

We propose a large area low cost manufacturing process for diffraction gratings with very small line-edge-roughness (LER) and defect-free surface using self-perfection by liquefaction (SPEL) and nanoimprint lithography (NIL). The manufacturing process is capable of producing diffraction gratings covering wavelength ranging from UV to LWIR. The manufacturing process starts with making a master grating template by scanning beam interference lithography (SBIL) and reactive ion etch (RIE). Then, the master grating template is duplicated to have many intermediate templates by high resolution NIL and RIE. The gratings on intermediate templates are further perfected by SPEL to greatly reduce LER and remove surface defect. Simultaneously in SPEL process, the grating profile is changed from trapezoid to sinusoidal, which is desired profile of diffraction gratings. By using carefully developed SPEL process, the template will have nearly perfect grating lines with very small LER, defect-free surface and desired sinusoidal profile. The template will be imprinted to replicate these nearly perfect gratings onto end-product substrate. NIL using Air Cushion Press (ACP) will be used to replicate these gratings faithfully without degrading its quality. The large area low cost manufacturing capability of NIL using ACP will significantly reduce cost of diffraction gratings made by this process. BENEFIT: Proposed works provide a manufacturing path to produce precision large area diffraction gratings at affordable cost to end user. In general, any application that needs a large area diffraction grating with superb spectrum performance will be benefited from this development. In foreseeable future, military surveillance and guided weapon system will likely take benefits from this development. By adding a large area diffraction grating together with optical detector with arrayed pixels, it becomes possible to obtain target images within a narrow spectrum band. The narrow spectrum imaging and band selection capability will tremendously improve performance of target finding, tracking, and identification. This means fast, accurate, and reliable battlefield surveillance and smarter guided weapons. Most importantly, this development can produce large area diffractive gratings with superb spectrum band selection cheaply enough for broad implementations on battlefield. Security force is another potential user benefiting from this development. The key technology SPEL developed in proposed works will have tremendous impacts on nanofabrication when feature size variation control becomes more and more challenging for making nano-devices. Potentially, the key technologies used and developed for proposed manufacturing process can also be used for making other optical devices, nanofluidic channel for bio-applications, and nano-wire based sensors.