Broadband Antireflective Structures on PMMA by Plasma Treatment

Stochastic subwavelength structures on polymethylmetacrylate (PMMA) surfaces were produced by low-pressure argon/oxygen plasma treatment. The modified surfaces show antireflective properties exhibiting low scattering losses depending on the size and the density of the structure. It is demonstrated that the antireflection performance is a function of the mean ion energy and working pressure that are controllable by process parameters, namely plasma power and gas flow. A model is suggested that assumes a self-assembling etch mask as reason for the growth of the pins with about 70-90 nm in lateral dimension and up to 600 nm in height.