Study On The Process And Templates’ Fabrication Of Nano- Imprint Lithography

Nanoimprint lithography is regarded as one of the most promising technologies for nano-pattern fabrication. And it has attracted broad interest all around the world as a low-cost, high-through-output, and high-resolution lithographic technique in recent years.In the UV-nanoimprint lithography, the novel hybrid nanoimprint soft lithography has been successfully used to fabricate large-area and high-resolution nano-patterns. But several problems remain unresolved. The residual layer of the imprinted patterns will seriously affect the nano-pattern transfer down to substrate, ICP etching is typically required to remove the residual layer, thus increasing the process and cost. Therefor it is necessary to obtain a uniform and minimized residual layer or even no residual layer to overcome the drawback and promote hybrid nanoimprint soft lithography technology in industry. In this paper, we have studied the basic process of UV hybrid nanoimprint lithography, and have summarized the basic parameters which affect the results of UV hybrid nanoimprint lithography, such as the viscosity, surface tension and concentration of the UV-resist, the speed of spin coating, the structure and area of imprint templates and the pressure of imprint, etc. Through experiments, we have established theoretical models about the effects of these parameters on the UV hybrid nanoimprint lithography. According to the theoretical models, we have accurately controlled the thickness of resist film by the concentration of UV-resist and the speed of spin coating. We choose the suitable resist by the comparison of viscosity and surface tension of UV-resists, then we change the pressure used in imprint to get a suitable depth of different nanostructures. So we can accurately control the thickness of residual layer. We have successfully obtained no residual layer imprint of various nanostructures in the UV hybrid nanoimprint soft lithography.In the thermal nanoimprint, the imprint template used directly determines the quality of the imprint patterns. The durability of the imprint template is therefore crucial for the thermal nanoimprint. Fabrication of conventional silicon template is expensive. In addition, because of the brittleness of silicon, the expensive silicon template is vulnerable to damage in hot embossing process, therefore is not suitable for actual production, which becomes the major limiting factor of thermal nanoimprint technology. To this end, we want to find a cheap and durable material to produce nanoimprint templates. Nickel has a high mechanical strength, good thermal conductivity and low thermal expansion coefficient, and the passivating reaction of the exposed nickel surface occurs in air. The resulting passivation layer is chemically inert and not susceptible to corrosion, which has its own certain anti-sticking properties. Therefore, nickel is very suitable for the production of thermal nanoimprint templates. The nanoimprint templates made from nickel have high mechanical strength, good toughness and a long life. On the other hand, the fabrication process of nickel templates is simple and low cost. Nickel instead of silicon is used to fabricate thermal nanoimprint templates, which is one of the most promising candidates of templates for industrial production. In this paper, we have studied the fabrication of nickel nanoimprint templates. We use low-cost electroplating techniques to copy structures from expensive silicon templates to duplicate the cheap nickel templates, thereby reducing the cost of the thermal nanoimprint, and promoting thermal nanoimprint technology to the industry in future.