The time dependent temperature distribution induced by electric current heating in a double edge cracked, unpassivated thin aluminum or gold film interconnect lines is monitored using a high resolution infrared imaging system. A pure aluminum or gold film, with a thickness of 0.2 μm, is deposited by high vacuum evaporation coating and patterned into test structures of varying widths. The operative mechanisms of mass transport are assessed in view of the monitored temperature profile. The pre-cracked aluminum film shows fine crack growth towards the positive electrode, which originates from the initial crack tips. The crack-tip temperature is close to melting, during propagation. After the initial crack propagation, a hot spot is formed between the two elongated cracks, and leads to failure. The crack growth generates a backward mass flow towards the negative electrode. The gold film shows a different pattern, in which the original cracks propagate towards each other with a slight tilt towards the negative electrode. The tip temperature is lower than the melting temperature. These time dependent failure mechanisms are rationalize using a proposed critical current intensity factor and a normalized current intensity rate, similar to the fracture toughness KIC for brittle fracture.

Issue Section:
Special Section Technical Papers
Topics:
Damage, Electric current, Fracture (Materials), Thin films, Electrodes, Temperature, Aluminum, Melting, Brittle fracture, Coating processes, Coatings, Crack propagation, Evaporation, Failure, Failure mechanisms, Flow (Dynamics), Fracture toughness, Heating, Infrared imaging, Resolution (Optics), Temperature distribution, Temperature profiles, Vacuum
1.
Adkins, C. J., 1983, Equilibrium Thermodynamics, Cambridge University Press, New York.
2.
Attardo
M. J.
, and
Rosenberg
R.
,
1970
, “
Electromigration Damage in Aluminum Film Conductors
,”
Journal of Applied Physics
, Vol.
41
, No.
6
, pp.
2381
–
2386
.
3.
Bastawros, A.-F., and Kim, K.-S., 1995, “Electro-Thermal Crack Growth Caused by Electric-Current Intensification,” Proceedings, Application of Fracture Mechanics in Electronic Packaging and Materials, EEP-11/MD-64, ASME, New York, pp. 238–244.
4.
Bastawros, A.-F., and Kim, K.-S., 1997, “The Role of Electric-Current Induced Heating in Damage Evolution at the Crack Tip in Thin Films,” Proceedings, Application of Fracture Mechanics in Electronic Packaging, EEP-20/AMD-222, ASME, New York, pp. 139–144.
5.
EchoTherm Manual, 1997, Version 4.2, Thermal Wave Imaging Inc., Lathrup Village, MI.
6.
Gardner
D. S.
,
Meindl
J. D.
, and
Saraswat
K. C.
,
1987
, “
Interconnection and Electromigration Scaling Theory
,”
IEEE Transactions on Electron Devices
,
ED-34
, pp.
633
–
643
.
7.
Ho
P. S.
,
1970
, “
Motion of Inclusion Induced by a Direct Current and a Temperature Gradient
,”
Journal of Applied Physics
, Vol.
41
, pp.
64
–
68
.
8.
Marieb
T.
,
Bravman
J. C.
,
Flinn
P.
, and
Madden
M.
,
1994
, “
In Situ Observations of Voiding in Metal Lines Under Passivation
,”
Materials Research Society Symposium Proceedings
338
, pp.
409
–
413
.
9.
Saka, M., Sasagawa, K., and Abe`, H., 1994, “Theoretical Analysis of Electro-thermal Crack Problem Considering Thomson Effect,” Proceedings, ASME meeting, AMD-193, 193, pp. 53–59.
10.
Sigsbee
R. A.
,
1973
, “
Electromigration and Metalization Lifetimes
,”
Journal of Applied Physics
, Vol.
44
, No.
6
, pp.
2533
–
2540
.
This content is only available via PDF.
Copyright © 1998
 by The American Society of Mechanical Engineers
You do not currently have access to this content.