Zoom-chirped DOW interference system for micro and nano-lithography

As scientific quests and engineering applications reach down to a nanometer scale, there is a strong need to fabricate three-dimensional nanostructures with regularity and controllability in their pattern, size, and shape, including chirped pitch. Interference lithography is considered to be the most efficient way to make submicron-scale periodic patterns over a large area with superior control of pattern regularity. In order to make a chirped nano-patterning with interference lithography technology, we propose a zoom-chirped interferometer as a novel manufacturing tool with more flexibility for 3-D nano-patterning fabrication. The optical concept of this novel zoom-chirped interferometer is based on the Fresnel division-of-wavefront (DOW) interference combined with a pair of half-cylindrical zoom lenses, which are located in front of a Fresnel 90°-mirror, to generate a cylindrical wavefront interfering with a plane wavefront in the system. The collimated beam will be used as the incident beam for the interferometer. The interference patterning between the cylindrical and plane wavefront is fully controlled, and the variation of the required chirped rate can be adjusted by moving one half-cylindrical lens in the system. This novel zoom-chirped interferometer is more flexible and stable than conventional interference-lithography systems for micro and nano-patterning fabrication.