Nanoindentation of crystalline silicon pillars fabricated by soft UV nanoimprint lithography and cryogenic deep reactive ion etching

Abstract

Nanomechanical properties of bulk and micro-pillared monocrystalline silicon are experimentally investigated using nanoscale depth-sensing indentation technique. Silicon pillar arrays with different crystal orientations, i.e., Si<100>, Si<110>, and Si<111>, are prepared by means of a top-down approach consisting of nanoimprint lithography and cryogenic dry etching. A three-sided Berkovich tip used during the experiments has provided highly resolved load-depth-curves and imprinted hardness impressions on the silicon materials. Depending on the aspect ratio of the pillars, the axial stiffness of the objects under measurement has to be considered. Corrected values of the elastic modulus are determined revealing direct nanomechanical comparison between silicon bulk and pillar structures. In summary, enhanced comprehension of elastic-plastic-response occurred within micro-structured silicon materials is shown, providing the potential to use silicon pillar arrays as fundamental material for accurate force measurements.