Adequate mechanical copper modelling for 2nd level interconnect structures

Abstract

This paper discusses the requirements for achieving adequate modelling of the mechanical behaviour of copper interconnect structures in electronic assemblies. In this context it focuses on an experimental approach to characterise the mechanical behaviour of representative copper specimens. For this purpose the general constitutive behaviour of pure copper will be discussed, in doing so covering the specifics of elastic response, the onset of plastic flow with respect to microstructure, as well as load history, and the resulting cyclic elastic-plastic behaviour. The discussion regarding an appropriate experimental methodology starts with considerations about specific deformations of representative thin stripe specimens during a standard tensile test. In the second part this discussion is developed into design ideas for appropriate experimental instrumentation, which enables one to determine the required properties of the representative specimens.