Large area fabrication of single micron features using two-photon polymerization with sub-nanosecond laser.

Single micrometer-sized features were fabricated on ARN-4340 photoresist using a 3D additive technique of two-photon polymerization (TPP). An economic TPP setup capable of producing a large area was developed in the lab using a sub-nanosecond laser. The Photo-initiator (2, 4 Diethyl-9H-thioxanthen-9-one) with a large two-photon absorption cross-section was used to enhance the polymerization. It was theoretically determined that the dimensions of the polymerized features depend on the concentration of the photo-initiator. A novel image-based focusing technique was developed to achieve uniform microsized features on a large area. In the proposed TPP setup, the developed focusing technique was used to determine the area over the sample, which can be polymerized in one go. To demonstrate the capability of the developed setup, microstructures of about 1 µm width were fabricated over an area of 4 cm². Further, the fabricated sample was used to develop a master mold of Polydimethylsiloxane, which can be used for a soft-lithography replication process. Also, the melt flow technique was explored to reduce the roughness in the fabricated structure. The multi-photon polymerization process using the sub-nanosecond laser is shown to be cost-effective and robust for large area microstructure fabrication. [ABSTRACT FROM AUTHOR]