Smectic hybrid oligo(dimethylsiloxane) liquid crystal for nanopatterning

Block copolymer self-assembly is a candidate resolution enhancement technique for patterning at future technology nodes. The technology is based on the micro-phase separation of chemically immiscible (eg polar/apolar) block copolymers that contain etch contrast (eg. organic/inorganic) into regular patterns (eg. lamellar or cylindrical) with periodicities between 10 - 100 nm. One of the challenges that remain for the implementation of self-assembly in nanopatterning is extendibility of the technology to smaller features. In contrast to block copolymers, liquid crystals are able to self-assemble at the molecular length scale (1-10 nm). The current work reports on a liquid crystal with inherent etch contrast and its self-assembly behavior. A monodisperse oligo(dimethylsiloxane) liquid crystal is synthesized via hydrosilylation and characterized. The formation of a temperature dependent tilted smectic phase with a periodicity of approximately 3.0 nm is demonstrated via differential scanning calorimetry, polarized optical microscopy, and x-ray diffraction. The director tilt is highly dependent on temperature (20° - 70°), while the layer spacing is relatively temperature independent (2.99 - 3.03 nm). Finally, we show that the liquid crystal forms lamellar sheets in thin films.