Balancing Innovation with Environmental Sustainability: Vapour Phase Patterning System for Controlling Block Co-Polymer and Polymer Brush Morphology

Abstract

The growth of the semiconductor industry and device miniaturisation has highlighted a need for novel and sustainable approaches to nanofabrication. Resource scarcity, increasing energy costs and environmental instability are major challenges to development in the semiconductor industry. As Integrated circuits (IC) become smaller, larger amounts of power and materials are required to pattern them. This increases ecosystem damage and puts strain on environmental resources. Improving sustainability in this industry is less costly and wasteful during the research and development stages of new patterning process in chip manufacturing. This study offers a framework for comparing emerging and conventional patterning techniques in terms of environmental impact and technological readiness. The emerging technology focused on in this research is Vapour Phase Patterning (VPP). VPP is a new patterning technology developed as part of this research to improve the technological readiness of polymer brush and block copolymer (BCP) patterning techniques. BCP patterning involves microphase separation of a BCP film and subsequent infiltration with inorganic species. The BCP film acts as a template which when removed leaves behind inorganic replicas. Polymer brush patterning involves inorganic infiltration of high-density grafted polymer chains. The polymer brush also acts as a template by determining the deposition area and thickness of the inorganic layer formed post polymer removal. VPP allows for the simultaneous, single-step, selective swelling of BCP nanodomains and polymer brushes to required templating dimensions whilst infiltration of metallic precursor preserves feature size selection, film thickness and morphology. This is all achieved without changing the molecular weight of the BCP or the grafting density of the polymer brush. VPP patterning capabilities are demonstrated using titanium isopropoxide (TTIP) for inorganic precursor infiltration of a wide range of different molecular weight polymer brushes and BCPs. After enhancing the industrial readiness of this emerging technology, the environmental impact was assessed using ex ante life cycle analysis (LCA). Ex ante LCA is used to compare the environmental performance of VPP patterning of polymer brushes to Atomic Layer Deposition (ALD) to produce thin films of specific nanoscale thicknesses. Additionally, comparisons are made in terms of film quality produced by ALD and VPP technologies. ALD is a widely used in industrial technique for precise growth of material vii layers at the atomic scale. Therefore, the outcomes of the ex-ante LCA and film quality comparisons assess whether VPP would result in reduced environmental impacts and retain film quality if it was used instead of ALD on an industrial scale. This research highlights the increasing need for researchers to incorporate life cycle thinking when developing new technologies to balance design innovation and functionality with environmental sustainability. Integrating LCA principles during the research and development phase of a technology can pre-empt significant environmental impacts and mitigate the substantial costs associated with redesigning technology to align with green chemistry principles during later industrial stages of development.