Fabrication of nano and micro optical elements by step and flash imprint lithography

The Step and Flash Imprint Lithography (S-FILTM) process is a step and repeat nano-imprint lithography (NIL) technique based on UV curable low viscosity liquids.1,2,3Investigation by this group and others has shown that the resolution of replication by imprint lithography is limited only by the size of the structures that can be created on the template (mold). S-FIL uses field-to-field drop dispensing of UV curable liquids for step and repeat patterning. This approach allows for micro and nano-fabrication of devices with widely varying pattern densities and complicated structures. Wire grid polarizers and micro lenses are two examples for optical components that can be formed using SFIL technology. Step and Flash Imprint Lithography Reverse (S-FIL/R) tone has been used to form resist patterns for a number of different device types 1,4,6. The authors have employed S-FIL/R and dry develop techniques to form resist patterns with 100 nm period useful for the fabrication of wire grid polarizers. S-FIL/R has a number of advantages over interference lithography techniques for the fabrication of sub 200 nm period grating structures including but no limited to pattern repeatability, vibration insensitivity, high aspect ratio feature formation, greater extendibility and high resolution. The authors have devised imprint and dry etching processes for resist and substrate patterning to form Al based wire grid polarizers with 100 nm pitch. The fabrication processes and resulting devises will be described. While S-FIL is useful for in the formation of resist patterned wafers, it is also capable of forming devices by functional material patterning. Polymer micro lenses are a good examples of functional material devices useful for a number of applications including CMOS and CCD cameras. The fact that lens geometry is defined by the template and requires no post imprint processing provides a strong advantage over current lens formation approaches. Recent results and the state of current micro lens fabrication by S-FIL is described.