Herein, we demonstrate the fabrication of sub-20 nm MoS₂ horizontal nanowire arrays on silicon substrates using a self-assembled block copolymer assisted in situ inclusion approach. Microphase separated long-range ordered polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer (BCP) line-space nanopatterns were achieved through thermo-solvent annealing. The patterns produced had long-range order and domain sizes > 1 μm. The BCP structures were lightly etched and modified by anhydrous ethanol to facilitate insertion of molybdenum precursor within the film maintaining the parent BCP arrangements. Horizontal ordered molybdenum oxide nanowire arrays were then fabricated by ultraviolet (UV)/ozone treatment at room temperature. The oxides were converted to sulphides by thermal evaporation at different temperatures in Ar/H₂ environment. X-ray photoelectron spectroscopy revealed the composition and phases of the molybdenum oxide and sulphide nanowires. Elemental mapping was performed to investigate the interfaces between the oxide and sulphide nanowires with the substrate surface. The formation and stability of the sulphide nanowires were studied at different temperatures. The photoluminescence and Raman properties were studied at different formation temperatures to investigate defects and estimate the number of layers.

Our goal is to develop a facile process to create patterns of inorganic oxides and metals on a substrate that can act as hard masks. These materials should have high etch contrast (compared to silicon) and so allow high-aspect-ratio, high-fidelity pattern transfer whilst being readily integrable in modern semiconductor fabrication (FAB friendly). Here, we show that ultra-small-dimension hard masks can be used to develop large areas of densely packed vertically and horizontally orientated Si nanowire arrays. The inorganic and metal hard masks (Ni, NiO, and ZnO) of different morphologies and dimensions were formed using microphase-separated polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymer (BCP) thin films by varying the BCP molecular weight, annealing temperature, and annealing solvent(s). The self-assembled polymer patterns were solvent-processed, and metal ions were included into chosen domains via a selective inclusion method. Inorganic oxide nanopatterns were subsequently developed using standard techniques. High-resolution transmission electron microscopy studies show that high-aspect-ratio pattern transfer could be affected by standard plasma etch techniques. The masking ability of the different materials was compared in order to create the highest quality uniform and smooth sidewall profiles of the Si nanowire arrays. Notably good performance of the metal mask was seen, and this could impact the use of these materials at small dimensions where conventional methods are severely limited.