Fracture toughness measurement of thin nanoporous films on stiff substrates
Dylan Morris, Robert F. Cook
Nanoporous low-dielectric-constant films constitute a class of materials that are plagued by fracture concerns and are not amenable to traditional fracture toughness measurement techniques. An indentation fracture toughness measurement technique has been developed for these materials. The experiment utilizes nanoindentation in combination with cube-corner indenters which create flaws are on the scale of the film thickness, about a micrometer. Interpretation of experimental results are a far-reaching generalization of the traditional Vickers based indentation test used for ceramics at the mesoscale. Cube-corner indentation fracture is dominated by crack-wedging effects that are not important for Vickers indentation. Film-substrate elastic coupling is very important, and is manifested in three distinct ways. After film-substrate coupling phenomena are identified, they are combined with acute indentation fracture models to form a complete thin-film indentation fracture mechanics model. The fracture toughness of two materials have been measured to be 0.09 MPa m1/2 and 0.05 MPa m1/2.
and Cook, R.
Fracture toughness measurement of thin nanoporous films on stiff substrates, 12th International Conference on Fracture, Ottawa, CA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=900922
(Accessed February 23, 2024)