Study On The Preparation And Application Of Nickel Stamps For Nanoimprint

Nanoimprint lithography is a simple method of full-size nanostructure replicate. Compared to traditional lithography, nanoimprint lithography has the characteristics of high resolution, low cost and high yield. The nanoimprint templates are the most important part of nanoimprint lithography technology. Generally, the nanoimprint templates materials are mainly silicon and quartz, while they are fragile and expensive. The nickel has the characteristics of corrosion resistance, heat resistance, and good mechanical properties (e.g., high strength, good toughness). So it is an important material to replace silicon as nanoimprint templates. In this paper, the preparation of nanodent nickel stamps and nanopillar nickel stamps were studied in detail, and the applications of nickel stamps in imprinting aluminum and ethylene-co-tetrafluoroethylene copolymer (ETFE) were also investigated.Firstly, the nanodent nickel stamps were prepared by combining with the UV nanoimprint technology and nickel electroforming. The elimination of internal stress and the treatment of anti-sticking layer of nickel stamps were also studied in detail. Owing to the existence of internal stress, the nanoimprint nickel stamps became bent. After the annealing treatment, the internal stress in the nickel stamps decreased greatly, and the nickel stamps became flat, which were suitable for nanoimprint. In order to decrease the surface energy of nickel stamps, an anti-sticking layer of monomolecular was deposited on the nickel stamp surface, after that the water contact angle increased from 49.6° to 129.7°. The anti-sticking layer can significantly improve the stripping effect during nanoimprint process.Secondly, on the base of fabrication of the nanodent nickel stamps, the nanopillar nickel stamps were fabricated after a two-step procedure for transfer of nanoimprint pattern. The nanodent nickel stamps were also eliminated the internal stress and deposited anti-sticking molecule. And the nanopillar nickel stamps turned smooth. The water contact angle increased from 41.7° to 126.9°, and the nanopillar nickel stamps had good hydrophobicity after the anti-sticking layer treatment.Thirdly, when the nanopillar nickel stamps were used to imprint aluminum, the regular nanodent arrays were obtained on the aluminum surface, and the regular alumina nanopore arrays could be formed by the anodic oxidation. Based on the above nanoimprint lithography, the nanodent structure aluminum substrate and nanocone PDMS templates were also fabricated. The nanodent structure aluminum substrate had good light trapping effect, which can be applied to the thin film solar cells.Finally, when the ETFE film became patterned by the hot embossing of nickel stamps, the properties of the material, such as surface hydrophobicity and light transmittance could be changed. The transmittance and surface water contact angle of patterned ETFE film can be improved compared with unpatterned ETFE film. The surface water contact angle of patterned ETFE film can increase to 161.3°, which turned to be superhydrophobic material. The patterned ETFE film could serve as packaging materials of the solar cells to improve the light transmittance and self-cleaning properties.