Research On Characteristics Optimization Of Nanoporous Materials Used In Integrated Circuit Copper Interconnect Process

With feature size of IC devices corresponding to sub 10 nm technology node,resistance-capacitance(RC)delay in the multilevel interconnections has become the dominant part of the overall chip performance.At present,the industry uses Cu/low dielectric constant(low-k)materials as IC interconnect structures to reduce RC delay.Low-k materials with ultra-low dielectric constants and excellent mechanical properties to meet back end of the line(BEOL).integration have become research hot-spots.Among them,nanoporous organosilicate glass(OSG)materials have attracted much attention due to their compatibility with silica-like frameworks and back end of the line integration processes,but the methods and mechanisms for optimizing their performance are still unclear.In this paper,the effects of terminal methyl groups on the properties of OSG low-k film materials were investigated by the evaporation induced self-assembly(ELSA)process.The mechanical properties of OSG low-k film materials were optimized by introducing phenyl groups.Surfactant-templated organosilicate glass(OSG)based low-k films are deposited by using TEOS/MTEOS mixture with different ratio and spin-on technology with the goal of understanding the effects of terminal methyl groups on chemical and structural properties.It is shown that despite of constant surfactant concentration these films have quite different properties when the changing of CH3/Si ratio.The most important changes are related to change of their hydrophilicity,change of mechanical properties,the pore size and to the shift of Si-CH3 peak position in FTIR spectra.The Young's modulus gradually decreases with increasing the terminal methyl groups concentration in the films.The pore size increases with concentration of methyl groups and changes from cylindrical to ink-bottle shape.The nature of S1CH3 peak shift is explained by using molecular mechanics simulation.It is shown that the reason of this shift is change of d?-p? hybridization in Si-O-Si bonds,which is affected by presence of CH3 group.The pore structure,dielectric,mechanical,hydrophobic properties of as-prepared benzene-based OSG thin films are studied.It is conformed the possibility of improving mechanical properties of OSG films by extending the connectivity of the silicon atom beyond its chemical coordination number.By introducing the porogen into the matrix,the k value can be improved,while it can not meet the requirement because of the absence of terminal groups.Given these properties include mesoporous structure,exceptional mechanical reliability,good thermal stability,it is shown that the trisubstituted benzene can be used as the bridging group.Therefore,the as-prepared benzene-based OSG thin films called hyperconnected network architecture can be considered as a promising candidate by improving the hydrophobicity.