Static and dynamic analysis of failure locations and void formation in interconnects due to various migration mechanisms

authored by

Kirsten Weide-Zaage, David Dalleau, Xiaoying Yu

Abstract

To avoid time-consuming long-term stress tests, reliability of metallizations is determined by accelerated stress tests with high-applied current densities under high-temperature conditions. During these tests temperature gradients and mechanical stress will occur, and the main failure mechanism in the metallization will be migration effects like electro-, thermo- and stressmigration. For reliability prediction of interconnects and via structures, numerical methods (as the finite element method FEM) can give a better understanding of the local heating and current crowding as well as mechanical stress. Mismatch of thermal expansion coefficients of the different materials leads to mechanical stress. Thermal-electrical-mechanical behavior can be calculated with the FE program ANSYS. With user programs the stress gradient as well as mass flux divergence distribution including electro-, thermo- and stressmigration can be calculated (Frac. & Duc. vs. Brit. Beh. - Theo., Modelling and Experiment. Symp. Boston, 1999). Concentration gradients are not considered in this calculation. The location of the maximum mass flux divergence determines the failure location in the static case. Simulation of dynamical behavior can be done by deleting elements with maximum divergence values in the model step-by-step (Proceedings of EuroSimE April, 2002). Out of this, void formation in the metallization as well as time to failure can be calculated. Static and dynamic simulations can be verified by measurements and in situ investigations in a scanning electron microscope (SEM). With the static analysis the weakest link in metallization structures can be identified. With this simplified model it is possible to determine the failure location as well as the void formation in the metallization structure. Also a design optimization is possible with the help of the simulation.

Organisation(s)

Laboratorium f. Informationstechnologie

Type

Article

Journal

Materials Science in Semiconductor Processing

Volume

6

Pages

85-92

No. of pages

8

ISSN

1369-8001

Publication date

02.2003

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Materials Science(all), Condensed Matter Physics, Mechanics of Materials, Mechanical Engineering

Electronic version(s)

https://doi.org/10.1016/S1369-8001(03)00075-1 (Access: Unknown)