Adhesion and acoustic emission analysis of failures in nitride films with a metal interlayer

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(97)00180-8· OSTI ID:599716

Bahr, D F; Hoehn, J W; Gerberich, W W ^[1]; Moody, N R ^[2]

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1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Science
2. Sandia National Labs., Livermore, CA (United States)

Tantalum nitride films (Ta{sub 2}N) are used as resistors in microelectronic applications owing to their long term stability and low thermal expansion coefficients. Previous studies of Ta{sub 2}N on sapphire substrates have characterized the nature of the coating both morphologically and mechanically. Low load indentations and continuous scratching techniques have been used to measure the adhesion of the films to sapphire substrates. When delaminations occur in these systems, reproducible failures occur at the interface between the film and substrate which allow quantitative measurements of the fracture energy to be made. This behavior also makes these systems ideal models for the study of hard, brittle coatings. Here, interfacial fracture has been induced between a tantalum nitride film with an aluminum interlayer on a sapphire substrate using nanoindentation. To identify failures for which a model calculation is valid, a commercial acoustic emission sensor has been used to study the details of the failure event. The interfacial fracture energy of the system with an aluminum interlayer under the loading conditions at the crack tip is approximately 8 J/m{sup 2}. Within narrow bounds, this toughness value is reproducible using three different theoretical approaches. The acoustic emission signal is used to determine a lower bound interfacial crack velocity of 5 m/s. The majority of the failure occurs at the aluminum-sapphire interface, suggesting that the fracture energy and crack velocity determined are related to the toughness of this interface and not the nitride-aluminum interface.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-96ER45574; AC04-94AL85000
• OSTI ID: 599716
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 12 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
ACOUSTIC EMISSION TESTING
CRACK PROPAGATION
FAILURES
FRACTURE PROPERTIES
INTERFACES
MICROELECTRONIC CIRCUITS