Nanoscale Defect Detection, Cleaning and Repair for Large Area Substrates

NanoMend will pioneer efforts to develop better, more integrated process inspection, cleaning, repair and control systems for nano-scale thin films on large area foils, and will do so in two exemplar vertical supply chains for functionalized polymer-coated paper products and for low cost flexible photovoltaics (PV). The aim is to demonstrate beyond state-of-the-art in-line detection, cleaning and repair of micro and nano-scale defects. The NanoMend strategy to develop novel optical inspection methods has three strands: 1.Enhance the effective lateral resolution and the vertical resolution of high speed optical inspection systems currently used to scan large area foils. 2. Develop high precision optical interferometric sensors with significantly higher spatial range and scan speed than existing laboratory interferometers. 3.Build and test prototype optical interferometers that can detect defects which have a spatial size below the diffraction limit (down to approximately 10nm) by utilizing a priori knowledge of the geometry of the defects and inverse modeling approaches. The NanoMend strategy for cleaning is to decrease defect density and enhance yield by using directional cleaning methods optimized for i) continuous operation to remove sub-micron defects from large area foils prior to barrier deposition, and ii) local removal of particles generated during fabrication of PV modules. Local repair techniques will be investigated in particular for interconnection defects detected near the end of PV module manufacture where the value of the work to be recovered is very high. NanoMend solutions proposed for inspection, cleaning and repair will be integrated into a) production of large-area photovoltaic panels for use in building-integrated systems with demonstrable long life (15-20 years) and b) production of polymer-coated papers used in fibre-based packaging solutions.