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

该项目的目标是为“在超高真空中通过表面活化方法制造功能材料互连技术”提供可靠的地位。采用表面活化室温接合技术的接合实验是在Max-Plank研究所的超高真空(UHV.10^-9Pa)接合装置和东京大学的普通高真空(HV.10^-5Pa)装置中进行的。阐明了界面微观结构、力学性能和电学性能之间的关系。透射电镜结果表明,HV制备的Al/Al界面微观结构受到H_2O等残余气体存在的影响。在界面处形成约10nm厚的中间非晶层。该层的存在影响界面微观结构。然而，接头的抗拉强度超过100MPa，界面电阻率低至小于10^<-12>OMEGA·cm^2。在特高压洁净气氛中制备的Al/Al接头具有直接键合界面，其表面在原子尺度上粘附。当表面被高压氧束溅射激活时，接头的抗拉强度比氩束溅射激活的强度低一半。在高压下制备的Al/Si_3N_4接头随着离子溅射、时间的增加而降低。其减少的原因是离子溅射在Si_3N_4表面形成了脆弱的紫层。然而，对于 Al/SiC 系统，接头的拉伸强度随着离子溅射时间的增加而增加，然后饱和。除了这些实验研究之外，还开发了使用分子动力学方法的计算程序来模拟室温键合过程。

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.