Inkjet coating combined with nanoimprinting for complex 3D patterns with progressive height increase and low residual layer

This manuscript investigates the use of Nanoimprint Lithography (NIL) for the development of devices in semiconductor, photonic, and biomedical industries. It focuses on the SmartNIL^® process, a method for patterning nanostructures on various materials. The study highlights the advantages of NIL, such as mass production of micro- and nano-scale structures, and the replication of complex structures. The manuscript discusses the importance of a precisely controlled and uniform residual layer for optimizing the optical performance of photonic components. It compares conventional spin coating with inkjet coating, emphasizing the latter's superior material efficiency and compatibility with the SmartNIL^® process. Two different resins were investigated: a nano-filler free material, EVG UV/A NIL (n=1.5), and a high refractive index resin containing TiO2 nanoparticles from INKRON (n=1.9). The results for both resins demonstrated excellent pattern fidelity with sharp edges and no filling issues across the entire imprint. The EVG UV/A NIL resin showed a uniform residual layer ranging from 30 to 40nm across the entire area, with the structure height gradually increasing from 80 to 275nm. The INKRON resin displayed a progressive increase in structure height from 68nm to 305 nm, with the thickness of the residual layer varying between 44 and 60nm. The results demonstrate the achievement of a uniform residual layer over a progressive height increasing pattern.