Mechanics of interfacial crack propagation in microscratching

Conference · Wed May 01 04:00:00 EDT 1996

OSTI ID:238551

Boer, M.P. de; Nelson, J C; Gerberich, W W ^[1]

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1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Science

There are two main issues regarding thin film debonding. The first is the nucleation of interfacial cracks, while the second is the propagation of cracks. From a mechanical testing point of view, scratch testing primarily serves to address the former issue, while indentation testing is a method of addressing the latter. A new probing technique has been developed to test thin film mechanical properties. In the Microwedge Scratch Test (MWST), a wedge shaped diamond indenter tip is drawn along a fine line, while simultaneously being driven into the line. The authors compare microwedge scratching of Zone 1 and Zone T thin film specimens of sputtered W on SiO{sub 2}. Symptomatic of its poor mechanical properties, the Zone 1 film displays three separate crack systems. Because of its superior grain boundary strength, the Zone T film displayed only one of these--an interfacial crack system. Using bimaterial linear elastic fracture mechanics, governing equations are developed for propagating interfacial cracks, including expressions for strain energy release rate, bending strain, and mode mixity. Grain boundary fracture strength information may be deduced from the Zone 1 films, while adhesion may be inferred from the Zone T films.

• Research Organization: Sandia National Labs., Albuquerque, NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States); Office of Naval Research, Washington, DC (United States)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 238551
• Report Number(s): SAND--96-1011C; CONF-960401--26; ON: DE96010742; CNN: ONR grant N00014-89-J-1726
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
ADHESION
BONDING
COMPARATIVE EVALUATIONS
COMPOSITE MATERIALS
CRACK PROPAGATION
ELECTRONIC EQUIPMENT
FAILURES
FRACTURE PROPERTIES
INTERFACES
LAYERS
MECHANICAL PROPERTIES
MECHANICAL TESTS
MICROSTRUCTURE
SILICON OXIDES
TUNGSTEN