Determination Of Character Of ULSI Interconnect Film By Surface Acoustic Wave And Application Of Numerical Algorithm

With the development of semiconductor technology, the feature size of integratedcircuit (IC) is decreasing. In deep submicron IC design, the interconnection delay andcrosstalk become the important factor that impacts the performance of IC. Theinterconnection of Cu/low-k is employed to replace the Al/SiO2interconnection,which relieves the problem of interconnection delay and crosstalk. The mechanicalcharacter of low-k influence the application in interconnection of IC, so a lot ofresearch has been developed to detect the mechanical character of low-k. Surfaceacoustic waves (SAWs) technique is a promising method to determine the mechanicalproperties of thin low dielectric constant (low-k) dielectrics by matching theexperimental dispersion curve with the theoretical dispersion curves. Surface acousticwaves (SAWs) technique can determine the mechanical properties fast, accurately andnondestructively. Matrix method can be used to calculate the theoretical dispersioncurve, but this method can’t calculate the theoretical dispersion curve of pattern filmof metal and dielectrics, and the roughness on surface of film and interface betweenthe film and substrate is neglected.Finite element method (FEM) is applied to obtain the theoretical dispersioncurves of SAWs. In this paper the dispersion curves of SAWs propagating onfilm/substrate structure and patterned film of metal and dielectrics are calculated. Therandom rough surface is established by Monte-Carlo method, the influence ofroughness on surface of film and interface between the film and substrate ondispersion curve is investigated. Then the3D interconnection model is established andthe theoretical dispersion curve propagating on this model is calculated.The adhesion is an important mechanical parameter. Surface acoustic waves(SAWs) technique is promoted for interfacial adhesion investigation. Spring boundarymodel is employed by introducing the parameters of distributed shear and normalspring constant per unit area (KTand KN) between the film and the substrate to takethe adhesion property into account to calculate the theoretical SAW dispersion curves.In this paper, both the porous and the dense low dielectric constant (low-k) films areinvestigated. Comparing with result by scratch, the consistency of result by SAWs andresult by scratch exhibit the validity of SAWs.