Amorphous Carbon Coated Silicon Wafer as Mold Insert for Precision Glass Molding

Press molding of glass is an emerging research area for micro-optics manufacturing. Despite advancements on coating layers of precision molds for glass molding, challenges still exist towards tailoring non-stick coating to provide consistent replication accuracy in thousands of repetitive molding cycles. In this study, atmospheric pressure chemical vapor deposition (APCVD) is introduced to synthesize nanoscale-thickness amorphous carbon layer on the surface of silicon wafer with liquid benzene as the carbon source and silicone rubber as the silicon oxycarbide (SiOC) source. The micro-morphologies of the coating layers under different conditions are obtained and analyzed. In the press molding, the coating exhibits extraordinary physical properties and can remarkably prevent silicon-glass adhesion under elevated temperature. Typical micro-structures, such as micro-pillar and micro-lens arrays on the amorphous carbon coated silicon wafers, are used as mold inserts in precision glass molding to replicate high-precision optical components. The results indicate that this amorphous carbon coated silicon wafer can replicate intricate micro-structures to glass substrates with high-precision dimensions without macroscopic adhesion. This coating technology will protect the mold materials with low adhesion and improve precision glass molding process.