Phase change nanodots patterning using a self-assembled polymer lithography and crystallization analysis

Crystallization behavior of scalable phase change materials can be studied on nanoscale structures. In this paper, high density ordered phase change nanodot arrays were fabricated using the lift-off technique on a self-assembled diblock copolymer template, polystyrene-poly(methyl-methacrylate). The size of the nanodots was less than 15 nm in diameter with 40 nm spacing. This method is quite flexible regarding the patterned materials and can be used on different substrates. The crystallization behavior of small scale phase change nanodot arrays was studied using time-resolved x-ray diffraction, which showed the phase transition for different materials such as Ge15 Sb85, Ge2 Sb2 Te5, and Ag and In doped Sb2 Te. The transition temperatures of these nanodot samples were also compared with their corresponding blanket thin films, and it was found that the nanodots had higher crystallization temperatures and crystallized over a broader temperature range. © 2008 American Institute of Physics.