A Low-Cost, "Maskless" Photolithography Method

NU 2008-079

Inventors

Hooman Mohseni

Short Description

A low-cost, "maskless" photolithography method to produce highly uniform arrays of nanopillars and nanoholes over a large area.

Abstract

The invention uses a self-assembled, ordered monolayer of hexagonally close packed (HCP) micro-spheres as optical lenses to generate deep sub-wavelength regular patterns over a large area on standard photoresist. It has been demonstrated that hole size is relatively independent of microsphere diameter, and so hole diameter is highly uniform even as microspheres vary in size. Microspheres are not formed directly on the substrate surface, which enables the use of any material compatible with a standard photoresist process.

Applications

solar cells (especially organic)
fuel cells
memory devices
artificial kidneys
nanofiltration
photodetectors
surface plasmonics
photonic crystals

Advantages

The invention has the following advantages over existing methods by which to form nanoholes and nanopillars:

Single Stage: The process is maskless
High throughput: Very large area (square meters, in principle) of nano-holes in a single shot
Highly Uniform: Hole size is highly uniform
Very Small: Hole diameter is much smaller than the wavelength of the UV light source
Flexible Dimensions: Hole spacing is independent of hole size
Highly Compatible: Can be used for any material compatible with standard lithography

Publication

Wu W, Katsnelson A, Memis O and Mohseni H (2007) A deep sub-wavelength process for the formation of highly uniform arrays of nanoholes and nanopillars. Nanotechnology 18: 485302.

IP Status

Issued US Patent No. 8,445,188