Block Copolymer Approach toward Selective Atomic-Layer Deposition of ZnO Films

High-quality thin films of ZnO fabricated with atomic-layer precision are attracting increasing interest in various applications beyond the conventional semiconductor industry. This has posed new demands for these thin films regarding, for example, the substrate compatibility and substrate-selective deposition. Herein, the impact of different underlining polymer substrates on the film growth characteristics of ZnO coatings fabricated with the atomic-layer deposition (ALD) technique is investigated. The resultant thin films are systematically characterized for the growth rate, crystallinity, surface morphology, hydrophilicity, and electrical conductivity. Most excitingly, based on the understanding gained for the ZnO film growth on the different homopolymer surfaces, nanoscale-patterned block copolymer (BCP) films via spin coating are designed and fabricated to demonstrate block-selective ALD of ZnO on these BCP surfaces. It will be shown that the polyethylene oxide parts of the BCP act as a significantly more passive surface for the ZnO growth than the polystyrene. Altogether, this concept couples two highly controllable methods—atomic-level precision of ALD and nanoscale precision of BCP substrates—into a simple and scalable way of producing diverse nanomaterial patterns.