Wafer‐Scale Vitreous Carbon Molds Enabling Precision Glass Molding of Aspherical Lenses

ABSTRACT Glass optics tend to be advanced in comparison to polymer‐based elements due to their higher refractive indices, better transmission in the UV and their thermal and chemical stability. As a result of this, glass components are commonly applied in demanding optical applications. Precision glass molding (PGM) is a standard process used to make aspheric glass lenses; however, conventional PGM uses precision‐ground tungsten carbide molds with anti‐adhesion coatings. This leads to high material and tooling costs, low scalability, and high energy use. Although wafer‐scale precision glass molding (WSPGM) increases the throughput and energy efficiency, the broader implementation of this process is limited by two factors: the adhesion of the glass to the mold and the cost of fabricating multi‐cavity molds. In this work, we report a wafer scale vitreous carbon mold (WSVCM) developed via the carbonization of a replica of furan polymer as a superior and scalable alternative to WSPGM. Owing to the intrinsic low glass adhesion and high thermal stability of vitreous carbon, the WSVCM avoids anti‐adhesion coatings, making the molding process easier; meanwhile, it also improves the durability during the use cycle of thermal repeatability. The mold is manufactured through replication‐based route from diamond‐turned master which allows high geometric accuracy along with much reduced tooling cost as compared with conventional precision grinding method. To guarantee dimensional fidelity, systematic precompensation of the master geometry is in place to compensate for carbonization induced shrinkage, there is also no issue in transferring aspherical profiles at wafer level. Furthermore, because of the integration of a concave spherical dots dicing architecture, thermomechanical stress concentration during cooling and demolding are mitigated, and reliable wafer level separation of the molded glass without fracture or residual adhesion is possible.