Study Of Patterning Mophology Control In Pseudoplastic Metal Nanoparticle Fluids Nanoimprint Lithography

The rapid development of integrated circuit needs the smaller and smallerfeature size of semiconductor devices. Traditional lithography has been reached to itstechnical limit because of the effect of light diffraction and interference.Nanoimprint lithography, which is one of the promising next generation lithographytechnologies, can realize nanopatterning by using non-optical methods.Traditional nanoimprint lithography (NIL) has serious disadvantages such ascomplex steps, high cost, low resolution etc. Synthesizing the advantages ofmetallic direct patterning NIL and pseudoplastic fluid’s shear thinning property, anovel idea is put forward. The pseudoplastic metal nanofluid, which could befabricated with metal nanoparticles, can be used as transfer medium in NIL.Paramaters that affect the fidelity of transfer nanopatterning are discussed in thispaper. The details are as following:1、The principle of different types NIL and its advantages and disadvantageshave been introduced firstly. Then novel methods to implement this technologybased on traditional NIL are described. New development and research in NILdedicated to overcoming the technical problems and expanding its application invarious fields. Meanwhile the selection criteria of transfer medium and theapplications of nanoimprint in different fields are discussed.2、In order to get high fidelity nanopatterning, COMSOL software is used tocompute the filling degree of pseudoplastic fluid based on the finite element method.And the results verify pseudoplastic fluid is superior to Newtonian fluid. Factors,such as transfer medium property, viscosity, imprinting speed, pressure, etc., whichwould affect filling degree, can be obtained from simulation results. High fidelitytransfer nanopatterning could be achieved by optimizing parameters set.3、The geometry size of nanocavity, which would be dependent on fabricationmethod, material property, technological processes, integrity of silicon, et al. in theprocessing of preparing template, determine the size of nanopatterning totally. It is therefore necessary to study the effect of different geometry size cavity on fillingdegree because the shape of nanopatterning is the same as cavity. COMSOLsoftware is used to simulate that how cavity defects affect the integrity of patterningand demolding. And reasonable solutions are proposed to solve these problems.4、Demolding stresses mainly exist in the neck of the patterning. If thedemolding stresses are big enough to go beyond the limit strength of transfermedium, necking will become more serious and then fracture appears. Through theanalysis of key parameters which would affect the microstructure integrity at theinitial time of demolding, analytic expressions of the forces acting on themicrostructure, e.g., adhesion force, internal force, friction force and other relatedparameters, as well as the effects of the friction coefficient, the Hamaker constant,the depth-width ratios of the patterning, and the size of the metal nanoparticles onthe integrity of patterning are obtained and analyzed. Factors that affect patterning’smaximum depth-width ratios have been achieved at the same time. The resultsprovide a theoretical basis for preparing high depth-width ratios nanowires with nofracture appears.Optimal parameter set are obtained by analyzing various factors that affect thefidelity of nanopatterning in different stages. The analysis results have importantguiding significances for the design of technological progress and the constructionof experimental facilities in future works.