Part I of this two-part work explored the instrumented-indentation and fracture phenomena of compliant, low dielectric constant (low-k) films on silicon substrates. The effect of film thickness and probe acuity on the fracture response, as well as the apparent connection this response to the perceived elastic modulus, was demonstrated. These results motivate the creation of a fracture model that incorporates all of these variables here in Part II. Indentation wedging is identified as the mechanism that drives radial fracture, and a correction is introduced that adjusts the wedging strength of the probe for the attenuating influence of the relatively rigid substrate. An estimate of the film fracture toughness can be made if there is an independent measurement of the film stress; if not, a critical film thickness for channel-cracking under the influence of film stress may be estimated.
Citation: Journal of Materials Research
Pub Type: Journals
fracture, indentation, low-k, nanoindentation, reliability