Thermo-Mechanical Fatigue as a Failure Mechanism in Interconnects

Published

October 16, 2008

Author(s)

Cynthia A. Volkert, R R. Keller, Reiner Monig, E Arzt, O Kraft

Abstract

The possibility of failure of interconnects in microelectronic devices due to fatigue during normal use is discussed. During their lifetime, devices experience many thermal cycles with temperature amplitudes as large as 100 C, due to current- and to power-cycling. Differences in the thermal expansison coefficients of the different materials comprising the device can lead to stress changes in the interconnects on the order of 150 MPa. Such a stress amplitude is sufficient to lead to fatigue damage in fine grained metals after as few as 1000 cycles. We demonstrate this through experimental observations of surface damage formation in unencapsulated interconnects that were thermo-mechanically cycled by the application of an AC electrical current. It is concluded that soft dielectric materials, which are now being introduced for the interlevel dielectric in devices, do very little to constrain the interconnects and may result in fatigue becoming a serious reliability problem in future device generations.

Citation

Applied Physics Letters

Pub Type

Journals

Keywords

a.c. reliability, electromigration, interconnect reliability, thermo-mechanical fatigue, thin film fatigue

Citation

Volkert, C. , Keller, R. , Monig, R. , Arzt, E. and Kraft, O. (2008), Thermo-Mechanical Fatigue as a Failure Mechanism in Interconnects, Applied Physics Letters (Accessed December 8, 2023)