Back

The Role of Adhesion and Fracture on the Performance Nanostructured Thin Film Devices

Neville Moody

Megan J. Cordill*, John M. Jungk**, David F. Bahr***, William W. Gerberich*

Sandia National Laboratories, Livermore, CA 94550

*University of Minnesota, Minneapolis, MN 55455

**Sandia National Laboratories, Albuquerque, NM 87185

***Washington State University, Pullman, WA 99164

Nanostructured materials are the basis for emerging technologies, such as MEMS, NEMS, sensors, and flexible electronics, that will dominate near term advances in nanotechnology. These technologies are often based on devices containing layers of nanoscale polymer, ceramic and metallic films and stretchable interconnects creating surfaces and interfaces with properties and responses that differ dramatically from bulk counterparts. The differing properties can induce high interlaminar stresses that lead to wrinkling, delamination, and buckling in compression, and film fracture (channel cracking) and decohesion in tension. In assessing performance, it is clear that bulk material behavior cannot be simply extrapolated to the nanoscale. It is also clear that one cannot simply measure properties, as severe limitations are imposed by test methods that are difficult or impossible to apply at the smallest size scales. As a result, the relationships between structure and properties, and especially with regards to adhesion and fracture, are undefined at the nanoscale. Understanding these relationships is critical to assuring performance and reliability of nanostructured materials and devices. They are also critical for building materials science based predictive models of structure and behavior.

A number of limitations can be overcome by advances in the use of smaller probes, in-situ techniques, and instruments capable of very high load and displacement resolutions. Other limitations can be overcome use of clever and innovative test techniques. In almost all cases, a multi-disciplinary approach between experimentalists and theorists is required to accurately relate test results to properties. In this presentation we will illustrate the difficulties and the promise for advances in understanding fracture and fracture processes at the nanoscale through application of new test techniques and novel approaches using two examples: thin ductile films on rigid substrates and hard wear resistance films on more compliant substrates. These examples highlight the challenges we face and new approaches we can take in addressing the role of adhesion and fracture on performance of nanostructured materials and devices.

This work is supported by Sandia National Laboratories, a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Neville R. Moody

Brief Bio:

Neville Moody is a Distinguished Member of the Technical Staff at Sandia National Laboratories in Livermore California. He received his PhD degree in Materials Science from the University of Minnesota in 1981. After joining Sandia National Laboratories, his research focused on the determination of hydrogen effects on deformation and fracture in titanium, stainless steels, and superalloys, employing experimental testing, modeling, and simulation techniques. For the past 15 years his research has included the study of deformation and fracture on the submicron scale in thin films and small volumes. He has authored or co-authored more than 140 publications, including invited reviews and a chapter in the encyclopedia on Comprehensive Structural Integrity, co-organized three International Conferences on Hydrogen Effects in Materials, six MRS symposia on thin films, nanomechanical behavior, and nanostructuring of materials, three regional materials and welding technology conferences, and recently co-chaired the 2005 MRS Spring Meeting in San Francisco. He is on the board of review for Metallurgical and Materials Transactions and is an active member of several MRS, TMS, and ASM committees. Dr. Moody is a Fellow of ASM.

Back

Top