Circular Double-Patterning Lithography Using a Block Copolymer Template and Atomic Layer Deposition

A novel and feasible methodology is developed to fabricate well-ordered, freestanding 1D n-ZnO/p-Si nanotube (NT) and nanorod (NR) arrays via double-patterning technology with block copolymer (BCP) self-assembly, atomic layer deposition (ALD), and inductively coupled plasma (ICP) dry etching. To obtain the well-ordered NT pattern, a self-assembled, Si-containing poly(styrene-block-4-(tert-butyldimethylsilyl)oxystyrene) BCP on an SU-8/p-Si wafer is employed as a template. After n-ZnO deposition on the self-assembled BCP template by ALD, an ICP etching process is performed to produce well-defined, independent n-ZnO/p-Si NT arrays. The insights into the nanoarrays presented here are directly applicable to the fabrication of n-ZnO/p-Si NT/NR patterns and Si NT/NR patterns by precisely controlling the ALD cycles and ICP etching time. The electrical properties of a single n-ZnO/p-Si NT are measured by conductive atomic force microscopy, and the results show the typical rectifying behavior of a nanodiode with superior electrical properties. This simple and useful approach provides a very convenient route for fabricating high-density nanodiode patterns. Additionally, the possibility of various applications is confirmed by simple analyses, including examinations of contact angle and reflectance. Furthermore, the wettability and antireflection properties can be controlled by changing the nanoarray morphology.