Research On Fabricaiton Of Nanostructures By Dynamic Plowing Lithography Based On AFM Tapping Mode

The recent and rapid development of nanotechnology has attracted increasing attention to the application of nanostructures in various fields: nanogrooves on polymers or metals providing nanochannel for nanofluidic chips,fabrication of periodic nanogrooves for nanogratings,nanodots or nanopits for surface-enhanced raman substrate or data storage and so forth.Therefore,nanostructures play an important role in nanoelectronic,nanophotonics and nanosensors.Many scholars have proposed various methods to fabricate nanostructures on a wide variety of materials and have devoted resources to exploring more controllable methods to obtain nanostructures with dimensions of several nanometers,such as focused ion beam lithography,electron beam lithography,and nanoimprint lithography.However,the complexity,strict environmental requirements,and high cost greatly impede the applications of these techniques.Efficient fabrication of nanostructures still faces enormous challenges.Considering the cost and the production efficiency,atomic force microscopy(AFM)tip-based nanolithography represents a better alternative.Machining techniques via AFM are relatively low-cost,simple,highly accurate and provide flexible control.Moreover,AFM can fabricate features on most materials.Dynamic plowing lithography is derived from tapping scanning mode.The cantilever is drived at resonance frequency.This technique is currently known as a simple and feasible method for fabricating high-resolution nanostructures and decreasing the friction.And the efficiency of experiments is improved dramatically with the in-situ measurement.However,this technique is still in the lack of in-depth theoretical research.The machining mechanism and fabricating nanostructures with controllable machined depth need to be further studied.Therefore,to solve the issues mentioned above,dynamic plowing lithography processing technique is investigated in detail.And the contents of this thesis contain:Firstly,material removal mechanism is investigated for AFM dynamic plowing lithography.Based on AFM tapping mode,a theoretical model is established based on the relationship between the tip energy dissipation and material removal volume to analyze the effect of nanogroove fabrication.Characterization on phase between machined surface and original surface is proposed to study the mechanical behavior change of polymer for tapping mode and dynamic plowing lithography.Furthermore,material removal mechanism is investigated for fabrication of nanopit,nanogroove with pile-up and none-ridge nanogroove.In addition,a molecular dynamics simulation model is developed to investigate the comparision between static and dynamic plowing lithgraphy of single crystal copper and study the material removal mechanism and surface generation.A fast-scan nanolithography method is proposed based on the DPL fabrication approach and employed to fabricate nanoscale pits with high throughput.The effects of the drive amplitude,molecular weight,sample modulus and drive frequency on the critical velocity and spacing distance between two pits are analyzed.Finally,8-bit ASCII code could be obtained with the arrays of the pits with eight columns,which provides a new method for data storage.The effects of machined parameters on machined nanogrooves are investigated based on theoretical and experimental analysis.In the nanogroove machining process for polymer,the effects of the drive amplitude,scratching velocity and scratching direction on the feature size of the machined nanogrooves are analyzed.In addition,a molecular dynamics simulation model based on dynamic plowing lithgraphy is developed to analyze the influence of the tip orientation on the machined depth,cutting force and slipping process.Moreover,fabrication of nanogroove on single crystal copper is investigated based on the experimental method.Novel processing methods are proposed for nanostructure fabrication with the combination of nanogrooves.DPL-based nanoscratching methods to fabricate protuberence and concave nanostructures are proposed.The effects of the machining parameters on the feature size are analyzed and the optimized parameters are obtained.Furthermore,arrays of nanogrooves and nanodots are fabricated with the combination of nanogroove and pile-up.Different shapes and high density nanodots provides surface-enhanced raman substrate for R6G moleculars.