Creep of Al Underlayer Determined by Channel Cracking of Topical Si3N4 Film

This paper presents the results of channel cracking experiments performed on a multilayered structure. Room temperature creep behavior of a metallic underlayer was studied by using a newly developed channel cracking method. By the analysis of a channel crack propagating under tensile load in an elastic Si3N4 topical layer, the creep properties of an aluminum underlayer were determined. The experimental results were compared with the results of room temperature creep studies performed on commercial Al and Al–Mg micro-wires. As expected, the viscosity of pure Al underlayer is less than that of these materials. It is about 50% of the viscosity attributable to the primary creep region of commercial Al micro-wires. Compared to the viscosity of a harder alloy, the viscosity of the pure Al underlayer is about 20% of that attributable to the primary creep region of Al–Mg micro-wires. The growing cracks are observed to terminate at surface flaws that relieve their stress fields.