Enhanced mechanical property through high-yield fabrication process with double laser scanning method in two-photon lithography

[Display omitted] •The double-step laser scanning method allows fabrication of micro 3D structures with exceptional mechanical performance.•The proposed method improves the mechanical properties of the initial interfacial layer between the structure and the substrate.•The induced strong crosslinking in the polymer prevents swelling and delamination, leading to enhanced mechanical properties.•The proposed method is further validated with large-scale microlens arrays, demonstrating improved process yields. Two-photon lithography (TPL) is a representative fabrication process for micro 3D structures with a sub-micron fabrication resolution. As the TPL process is developed and commercialized, the TPL process requires higher process yield to be a considered reliable manufacturing technique for mass production. However, delamination is one of the main factors that reduce the yield of the TPL process. In this study, a double-step laser scanning method is proposed as a reliable high-yield TPS process to reduce the delamination effect. The method entails a simple process that polymerizes the initial interfacial layer between the structures and substrate twice. The additional laser scanning step induces a strong crosslinking in the polymer, and thereby preventing swelling and delamination. Furthermore, the effectiveness of the method is evaluated with large-scale microlens arrays. Although the process time is slightly increased, the process yield is significantly improved through the use of the double-step laser scanning method. Hence, the double-step laser scanning process can be employed as a reliable additive manufacturing process for various 3D microscale devices, and more importantly, it can be used to increase the manufacturing yield through the reduction of defects caused by surface delamination.