Patent ID: 7225681
Filing Date: 2007-06-05
Classification: G01N,G01R,H01L

Abstract:
1. A method for evaluating a material by a stress-generating test tool, comprising the steps of: providing an elongated elastic probing tool shaped to transmit force to a probing tip; providing an evaluation object shaped as a stack of adhering layers, including sequentially a layer of an insulating material-to-be-tested, a layer of a first metal, a layer of a barrier metal, and a top layer of a second metal, said second metal ductile relative to said first metal; establishing a numerical correlation between a cracking in the barrier metal layer caused by probing and a damage in the layer of insulating material-to-be-tested; selecting a first location of said top metal layer; probing said first location by touching said tool down on said first location, and exerting a controlled amount of force by said tool so that said tip generates an imprint while concurrently generating compressive and shear stress in said sequential layers under said top metal layer; lifting said tool from said first location and repeating said probing step a predetermined number of times at said selected first location; selecting a predetermined number of fresh locations of said top metal layer and repeating said probing step so that the number of touchings provide a pre-determined statistical confidence level; removing said top metal layer by a chemical etch solution so that said etch solution also penetrates into any stress-created cracks of said barrier metal layer underneath said imprints, and further dissolves a portion of said first metal layer, generating cavities in said first metal layer; recording the occurrence of all first metal cavities; and correlating said occurrence of said cavities with said probing.