Fabrication and characterization of master for nano-imprint lithography trough solid state dewetting.
Barri C., Fagiani L., Cattoni A., Bollani M.
Solid-state dewetting (SSD) is a natural shape instability occurring in thin solid films when heated at high temperature: it transforms a flat layer in isolated islands in a timeframe independent of the sample size. Being a spontaneous phenomenon driving changes of morphologies, it offers interesting technological perspectives. The aim of this work is to use SSD as an alternative way to a standard lithographic approach, or in combination with it, to produce over arbitrary scales random or order patterns to be used as master for soft nanoimprint lithography (NIL). Controlling the dewetting instability using amorphous Ge, we report the nanofabrication of patterns of Ge islands. To control their final shape and distribution, different Ge thicknesses and annealing temperatures have been tested employing a short time-consuming process. Then, the obtained patterns have been transferred in the Si substrate to obtain a scalable master for NIL. The combination of the two techniques, considering their capability to pattern large surface area at low cost, represents a promising alternative to texturize, for example, the back-mirror of ultra-thin solar cells.