Interconnection of Functional Materials by Means of a Surface Activation Method in Ultrahigh Vacuum

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The aim of the project shall be giving an assured status to 'making interconnection technique of functional materials by the surface activation method in an ultrahigh vacuum'. Bonding experiments by the surface activation room temperature bonding technique were made both in an ultrahigh vacuum (UHV. 10^<-9>Pa) bonding apparatus of Max-Plank Institute and in a regular high vacuum (HV, 10^<-5>Pa) apparatus of the University of Tokyo. The relationship among microstructures, mechanical properties and electrical properties of the interface was clarified.Transmission electron microscopy showed that the microstructure of Al/Al interfaces prepared in HV was affected by the presence of residual gas such as H_2O. An intermediate amorphas layer of about 10nm thickness was formed at the interfaces. The presence of the layer affects the interfacial microstructure. The tensile strength of the joint, however, is more than 100MPa and the interface electrical resistivity is as low as less than 10^<-12>OMEGA・cm^2.Al/Al joints prepared in a UHV clean atmosphere have direct bonding interfaces whose surfaces are adhered in the atomic scale.When surfaces are activated by an oxygen beam sputtering in HV, the tensile strength of the joints is less by half than the strength of those activated by argon beam sputtering.The tensile strength of Al/Si_3N_4 joints prepared in HV decreases as the ion sputtering, time increases. The reason of the decrease is that the fragile laver is formed at the surface of Si_3N_4 by the ion sputtering. However, in case of Al/SiC system the tensile strength of the joints is increasing and then saturated as the ion sputtering time increases.In addition to those experimental studies a calculation program using a molecular dynamic method was also developed for the simulation of the room temperature bonding process.