Abstract
This paper aims at the evaluation of crack initiation along the interface between sub-micron films. The stress singularity field in the vicinity of the edge due to the mismatch of deformations of films governs the crack initiation. Especially, a crack initiates at the corner point where singularity filed of stresses appears strongly, but it is not easy to clarify its mechanism because of the difficulty of controlling the crack initiation and the complication of the structure of the corner. In this paper, the specimen and loading system for interface cracking at the corner point are proposed and the interface strength between Si3N4 and Cu films in multi-layered films on the silicon substrate for an advanced LSI is measured. By using a three-dimensional finite element analysis with sub-modeling method, the stress singularity field in the vicinity of the corner of interface where the crack initiates is revealed. The interface strength of crack initiation can be measured on the basis of fracture mechanics concept and the criterion of mixed-mode interface fracture at the edge or corner is examined.
