Effects of substrate compliance on fracture of thin hard films


Neville R. Moody, nrmoody@sandia.gov1, Megan J. Cordill, megan.cordill@oeaw.ac.at2, Marian S. Kennedy, mskenne@clemson.edu3, Thao D. Nguyen, vicky.nguyen@jhu.edu4, David P. Adams, dpadams@sandia.gov1, John A. Emerson, jaemers@sandia.gov1, David F. Bahr, dbahr@wsu.edu5, and E. David Reedy Jr., edreedy@sandia.gov1. (1) Department of Hydrogen and Metallurgical Science, Sandia National Laboratories, P.O. Box 969, MS9402, Livermore, CA 94551-0969, (2) University of Leoben, A-8700 Leoben, Austria, (3) Clemson University, Clemson, SC 29634, (4) Johns Hopkins University, Baltimore, MD 21218, (5) Washington State University, Pullman, WA 99164
Deformation and fracture of thin hard films on compliant substrates are key factors governing the use of flexible substrate devices for medicine, biology, and defense. However, the effects of substrate compliance on film performance are not well defined. We are therefore studying these effects using substrates that span two orders of magnitude in compliance and hard tungsten films to minimize film plasticity effects. Following film deposition, high compressive film stresses triggered delamination and buckling. It occurred most readily on compliant PMMA substrate samples. But unlike films on more the rigid substrates, the buckles on PMMA continued to grow until the films spalled. In this presentation, we will use test and simulation results to show how substrate compliance and inelasticity affect deformation and fracture providing a means to tailor device performance. This work was supported by Sandia National Laboratories, a Lockheed Martin Company for the USDOE NNSA under Contract DE-AC04 94AL85000.