Study On Characterization Methods Of Electric Properties Of Dielectric Thin Films Based On MIM Structures

With miniaturization,thin-film,and high-frequency of integrated circuits,dielectric thin films have been used widely.However,as for the accurate extraction of dielectric properties of thin films,there is still not a unified and perfect standard or technique so far.The study on characterization techniques of electric properties of dielectric thin films has great significance and good application prospects.The results will be influenced by the parasitic effects inevitably,when Metal-Insulator-Metal structure(called MIM structure)is used to characterize the dielectric properties(dielectric constant εr and loss tangent tan δ)of thin films.And the accurate extraction of dielectric properties of thin films is mainly depend on the elimination of parasitics.Therefore,a series of studies about the accuracy of dielectric thin films characterization technique based on MIM structures have been going on in this paper,and SiO2 thin films is regarded as the research objection.1.The Differential Method of dielectric properties of thin films has been investigated in depth.A series of MIM structures with different inner diameters have been designed,and the results extracted directly from single strutures have been analysed contrastively,leading to the study of the Differential Method.In this paper,the effect of different combinations of two MIM structures with different inner diameters in this method,as well as different thinness and materials of the bottom electrode of these structures,on the characterization results has been mainly investigated.The results show that:1)the characterization results of different combinations of two MIM structures with different inner diameters have some differences among each other.Andεr extracted from the combination DM65-55 is 3.85,its accuracy can reach 98.7%;And tanδ is in an acceptable range.2)The variation of thinness of bottom electrode has a slight effect on the extraction of εr,and tanδ is decreasing with the increase of the thinness of bottom electrode.3)The variation of materials of bottom electrode has a big effect on tanδ,and it is decreasing with the increase of conductivity of electrode materials.2.The complementary technology of the Differential Method,i.e.,the Rs Subtracted Technology has been studied to exclude the additional resistances which have not been taken into account in the Differential Method.The results shows the corrected tanδextracted from this method doesn’t show strong frequency dependence anymore,and it’s closer to the reference value.3.The R-L Equivalent Method and R-Cp Equivalent Method have been explored.These methods can weaken the parasitics during the extraction of thin films dielectric properties through only one MIM structure.Parasitic resistance R and parasitic inductance L are axtracted by the R-L Equivalent Method;And parasitic resistance R and parasitic capacitance Cp are axtracted by the R-Cp Equivalent Method.The parasitic resistance R from these methods are close.4.Finally,the results from the Differential Method,and Rs Subtracted Technology,the R-L Equivalent Method and the R-Cp Equivalent Method has been compared and analyzed.The analysis shows that parasitic capacitance Cp has a bigger effect on εr than parasitic inductance L.Therefore,εr extracted from the R-Cp Equivalent Method is more ideal compared with that from the R-L Equivalent Method,and it is closer to that from the Differential Method.As for tanδ,the results from both the R-L Equivalent Method and the R-Cp Equivalent Method are both ideal,and are closer to the results extracted from the Rs Subtracted Technology.