Preparation And Study On The Structure-Properties Of Fluorinated Polyimide Film

With the development of Ultralarge-Scale integration(ULSI)in the microelectronics industry toward high speed,high integration and miniaturization of electronic devices,low dielectric constant(?)materials have become an urgent need.Low-? dielectric materials can effectively reduce the capacitance between metal interconnects,the lines crosstalk noise,the resistance-capacitance delay,and circuit dissipation.Polyimide(PI)materials have excellent electrical properties(??3.0-4.0,loss?0.001),excellent high and low temperature resistance and mechanical properties,and low moisture absorption.They are widely used as dielectric materials in the field of microelectronics.As one of the most promising polymers for next-generation high-performance interlayer dielectrics,the study of low-? polyimides has also attracted widespread attention.Introducing fluorine-containing structure or porous structure is the most common way to decrease the dielectric constant.In order to obtain lower-?polyimide films,and explore the deeper mechanism of lower-? of polymer so as for the structural design.This work mainly investigated polyimide films with two different fluorine-containing diamine monomers,based on the experimental basis,combined with molecular simulation software Gaussian and Materials Studio to establish the relationship between structure and properties systematically.Based on the copolymerization modification of 4 types of traditional polyimide films of BPDA/PDA,BPDA/ODA,PMDA/ODA and 6FDA/ODA,firstly selects a biphenyl rigid fluorine-containing diamine monomer,2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl(TFDB),adjusting the copolymerization ratio and reaction conditions,prepared a series of PI films with different fluorine content,together with molecular simulation technology,discussed the influence mechanism of TFDB structure on the dielectric properties of PI films,as well as the effects on mechanical properties and thermal properties.The results show that the increase of TFDB effectively reduces the dielectric constant of the PI film,and the lowest s is about 2.9(1MHz).At the same time,the introduction of the TFDB structure maintains the mechanical properties and thermal properties of the PI films,especially the thermal expansion coefficient(CTE)of the film.In addition,two parameters of BPDA/PDA/TFDB system PI ealculated by molecular simulation,including free volume(FFV)and unit volume molar polarizability(?/Vvdw)better reflect the law of dielectric constant.Further research on the influence of the flexible bridging structure on the dielectric and other properties of PI film,based on 4 types of polyimide films,BPDA/PDA,BPDA/ODA,6FDA/PDA,introducing 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane(HFBAPP)monomer for copolymerization modification,prepared a series of PI films with different fluorine content,and further explored with molecular simulation technology.The results show that the system with the lowest dielectric constant can be reduced to below 2.71(1MHz).Mechanical property of polyimides can be adjusted by changing in monomer configuration.But it will result in a higher coefficient of thermal expansion.The results of molecular simulation well reflected the law of dielectric constant,and realized the analysis and prediction of glass transition temperature,tensile modulus and thermal expansion coefficient.