Research On The Replication Process Of Nickel Nano-imprint Stamp

Nano-imprint lithography is a whole new kind of process to replicate micro and nano structures.It is proposed in the1990s by the Chinese-American scientist Stephen Chou. Instead of the traditional optical exposure lithography technology by1:1physical imprint. It breaks the limitation due to the wavelength of light and can fabricate structures from a few nanometers to several hundred microns in size. With the continuous development of MEMS/NEMS technology, nano-imprint lithography has become one of the focused micro-nano graphics replication process in recent years,and it is considered to be one of the most potential nano lithography technique to replicate large area nanostructures with high-resolution. However, there are some certain technical difficulties of the industrial application of nano-imprint lithography.The fabrication of nano-imprint stamps is one of the main bottleneck restricting the development of nano-imprint lithography. Nano-imprint stamp is the most important tool of nano-imprint lithography techniques, the traditional materials are silicon and quartz, but they are brittle and expensive. The researchers are studying a more suitable material as nano-imprint stamp. This article research on nickel nano-imprint stamp, focused on its replication process, the residual stress, surface anti-stick layer deposition and nano-imprinting experiments. It has laid the foundation for high-volume, large area of the nickel nano-imprint stamps production.In this paper, we proposed two methods to replicate the nickel nano-imprint stamp via nano-imprint technology and micro-electroforming process. One is based on the SU-8photo resist. It through two imprint process to transfer nanometer structures.The metal nano-structure is formed by a electron beam evaporation process, and the supporting backplane was grown through micro electroforming process. The replicated structure is contrary to the original structure by this method. Another is based on the IPS which is a Flexible polymer. During this process, only once imprint process is needed, nano structures are formed by micro electroforming deposition. The replicated structure is same to the original structure.Due to the micro-electroforming process of depositing a metal, the nickel stamp exists the residual internal stress and becomes bent. In order to eliminate the residual internal stress, we make a vacuum annealing experiments with the temperature400℃and keeps2hours to the replicated nickel stamp. After the annealing process, there is a great reduction of the internal stress and the replicated nickel stamp becomes smooth and suitable for embossing.In order to reduce the surface energy of the replicated stamp to avoid the adhesion phenomenon during the embossing. We deposited an anti-sticking layer on the replicated stamp surface.The material of anti-sticking layer is (CF3(CF2)7CH2CH2PO2(OH)2) named fluorinated alkyl phosphonic acid derivative. The water contact angle measurement result is127.8°.It reduces the surface energy of the nickel stamp greatly after deposition anti-sticking layer. We have made a nano-imprint verification test using the replicated stamp, the test results shown the replicated nickel stamp have no size loss. It has verified that the entire replication process is reliable.