Ultrahigh density sub-10 nm TiO2 nanosheet arrays with high aspect ratios via the spacer-defined double-patterning process

Abstract

A novel approach for fabricating ultrahigh-density sub-10 nm TiO2 nanosheet arrays with high aspect ratios by incorporating the spacer-defined double-patterning process with nanoline templates via atom layer deposition (ALD) was demonstrated. A nanoline template can be fabricated readily by pattern transfer from a thin silicon-containing block copolymer film into a thick crosslinked organic polymer layer. The excellent thermal stability of the crosslinked organic template allowed the high-temperature ALD process to deposit the TiO2 thin film conformally on the nanoline template. After the template was removed using dry etching and calcination, a highly crystalline anatase TiO2 nanosheet array with a length of several micrometers was obtained. The thickness of the resulting TiO2 nanosheet could be controlled below half the space of the originally defined nanoline template by incorporating the spacer-defined double-patterning process using ALD. This facile and scalable method could be a useful technique for fabricating ultrahigh-density arrays of various inorganic nanosheets with high aspect ratios.