3D features on plastic substrate by combining thermal and UV-nanoimprinting

Plastics offer a flexible and cost-effective substrate material for integrating printed electronics and optics. Plastics can be used in fabrication of various devices, e.g., optical gratings, printed transistors, flexible displays and solar cells, among others. Nanoimprinting is a promising candidate for low-cost and high-throughput method for pattern transfer of submicron size features on various substrates. Thermal Step and Stamp Imprint Lithography SSIL is a sequential imprinting method in which features on a small silicon master stamp are replicated into thermoplastic material. The method can be combined with UV-nanoimprinting to fabricate 3D structures. Hereby demonstrated process offers a novel method to fabricate flexible polymer stamps with 3D features for roll-to-roll nanoimprinting. In this work, we report on a method to fabricate 3D polymer stamps by combining thermal SSIL and UV Step and Stamp Imprint Lithography (UV-SSIL). In the first step 100 x 100 mm2 PET substrate is patterned by thermal SSIL using a small silicon stamp with micron size test structures. In the second step, submicron features of a quartz stamp are added on the micron size patterns by UV-SSIL. Finally, the patterned PET substrate consists of micron scale recessed and submicron scale elevated features. The pattern replication was realized using pressure of 5 MPa at 150 °C. In this experiment the two layer were place using rough alignment of about 10 ìm, but adding proper alignment mark design enables accuracy of 250 nm for the current equipment set up