A deep sub-wavelength process for the formation of highly uniform arrays of nanoholes and nanopillars

We report a low-cost and high-throughput process for the realization of two-dimensional arrays of deep sub-wavelength features using silica and polystyrene spheres. The pattern size in this method is a weak function of sphere size, and hence excellent size uniformity is achievable. Also, the period and diameter of the holes and pillars formed with this technique can be controlled precisely and independently. Moreover, the patterns can be formed in conventional negative and positive photoresists, and hence this approach is compatible with a wide range of existing processing methods. Although we achieved hole sizes of ~250 nm with a broadband UV source centered at 400 nm, our simulation results show that patterns as small as 180 nm should be achievable at a wavelength of 365 nm.