Research On The Next-Generation Plasnomic Nanolithography And Nanoimprint System

Conventional optical lithography is limited by the diffraction limit,and the resolution is only ?/2.With the development of the semiconductor integrated circuit industry,how to obtain sub-wavelength patterns at low cost has attracted increasing attention.A series of ultra-high resolution lithography methods such as electron beam lithography,focused ion beam etching,extreme ultraviolet lithography,surface plasmon nanolithography and nanoimprint lithography have been extensively studied.Surface plasmon nanolithography and nanoimprint lithography attract many attention for their high output,low cost and simple working environment.Surface plasmons with high frequency only exist in the near field and decay rapidly away from the exit surface.Therefore,short exposure depths limit the practical application of SP nanolithography.Nanoimprint lithography can replicate the nanostructure by mechanically pressing the template on the substrate.The resolution is only related to the template,showing strong competitiveness in industrial applications.In this paper,the plasmon direct writing lithography system with resonant cavity is carried out.Two kinds of plasmon resonant cavity structures are designed to coupled and amplified the evanescent wave.The reflector is designed to compensate the transmission loss.The plate-to-roll nanoimprint lithography system is designed to achieve nanostructure replication with low cost and high efficiency.This system offers great potential in the manufacture of the nanostructure widely demanded in flexible electronics.1.The optical properties of bowtie structure are investigated by numerical simulation.The mode analysis of metal-dielectric-metal(MIM)structure was carried out.We discuss the effect of dielectric layer thickness on the propagation constant.According to the index matching,PMMA is designed as the spacer layer in our work.The evanescent wave is coupled and amplified by the MIM structure.The field distributions in the photoresist of bowtie lithography system with or without MIM structure are compared.The contrast function describing the exposure results is defined to calculate the achievable resolution of direct writing lithography system with or without MIM structure was quantitatively described.Numerical simulations show the resolution of the direct-writing nanolithography system is less than 45 nm in a 40-nm photoresist.The effects of different parameters on bowtie fabrication in FIB process are discussed.The experiment results are sonsistent with the experimental results.2.We demonstrate a specially designed resonant metamaterial with epsilon-near-zero(ENZ)and nanoantenna to enhance the exposure depth in plasmonic direct writing more than 10 times.The ENZ metamaterial composed of a Ag/Si3N4 multilayer thin film,converts the evanescent field generated by the bowtie aperture nanoantenna to propagating waves with low divergence and high collimation.Deep sub-diffraction limited resolution of less than 65nm(?/7)with exposure depth greater than 100 nm is achieved.This work makes the combination of nanoscale aperture antennas with an ENZ metamaterial attractive for many practical applications such as semiconductor fabrication,new energy,optical integration and biotechnology.3.A plate-to-roll nanoimprint is designed to achieve high-speed,large-scale and high-resolution nanoimprint process.The maximum stress distribution during demold process is analyzed by finite element method.The study of the residual layer thickness is carried out.4.By using the plate-to-roll nanoimprint lithography,wire-grid polarizers with 75nm resolution are successfully fabricated.The transmittance and extinction ratio are in agreement with the simulation.A silion metasurface is designed to explore the influence of residual incident light on the output field.We prove that the metasurface can be replicated by nanoimprint at low cost and high efficiency.