Synthesis of ZnO-Based Adhesion Promoter Layer at Low Temperatures for Copper/Glass Metallization

Abstract The current study focuses on ZnO-metal oxide layer as an adhesion promoter layer. This enables electroless plating without etching or sensitization as used by the conventional process followed by galvanic metal plating directly on glass. ZnO thin films are prepared on industrial Borofloat (BF33) glass using simple wet chemical methods involving eco-friendly precursors. These methods are the successive ionic layer adsorption and reaction process and the chemical bath deposition process. ZnO fabrication chemistry, the number of iterative cycles, time, and the bath temperature (60-80°C) are optimized for an effective ZnO film thickness, properties on glass substrate, and interaction with electroless Cu. Agitation and heat treatment are introduced to observe their effect on the fabrication process and adhesion. Thus, ZnO films are fabricated at a low temperature of ~70°C compared to other conventional methods > 380°C. The ZnO film indicates improved properties in terms of microcrystalline structure, roughness, and porosity to some degree with these varying parameters. Electroless Cu deposition demonstrated a good adherence on these ZnO films, with a peel strength greater than 6.8 N/cm. This peel strength remained unchanged for a film thickness up to < 3 μm for electrodeposited Cu films.