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A diffusive creep model for electromigration-induced damage
Thin Solid Films, 83 ( 1981 ) 208
208
ELECTRONICS AND OPTICS
A DIFFUSIVE CREEP MODEL FOR ELECTROMIGRATION-INDUCED DAMAGE* J. R. LLOYD I B M Data Systems Division, East Fishkill, Hopewell Junction, N Y 12533 (U.S.A.) S. NAKAHARA Bell Laboratories, Murray Hill, NJ 07497 (U.S.A.)
Electromigration-induced damage in thin metallic film conductors generally occurs by the formation of voids and extrusions (hillocks) at grain boundaries. The origin of this damage, in particular void damage, has been studied theoretically by several investigators over the years. In these treatments, void formation has been analyzed in terms of classical nucleation from a supersaturated solution of vacancies. Although a supersaturation of vacancies undoubtedly exists in a film experiencing electromigration, the origin of these vacancies has yet to be adequately identified. Since electromigration-induced damage is an important cause of failure in semiconductor circuits, our investigation sought solutions to the problem. Recently, we proposed a model for electromigration-induced void formation where stress-induced vacancy generation at the grain boundaries supplies vacancies that diffuse into the neighboring lattice and leads to grain boundary thinning. This model could account for our transmission electron microscope observations as well as for the presence of compressive stresses and the absence of tensile stresses in films undergoing electromigration, as observed by Blech. In this paper we shall report further theoretical considerations on the problem of grain boundary vacancy generation and we shall also present a model for electromigration-induced damage where void and hillock growth is treated by an application of the well known Herring-Nabarro diffusive creep theory.
*Abstract of a paper presented at the International Conference on Metallurgical Coatings, San Francisco, CA, U.S.A., April 6-10, 1981. 0040-6090/81/0000-0000/$02.50
(C Elsevier Sequoia/Printed in The Netherlands
208
ELECTRONICS AND OPTICS
A DIFFUSIVE CREEP MODEL FOR ELECTROMIGRATION-INDUCED DAMAGE* J. R. LLOYD I B M Data Systems Division, East Fishkill, Hopewell Junction, N Y 12533 (U.S.A.) S. NAKAHARA Bell Laboratories, Murray Hill, NJ 07497 (U.S.A.)
Electromigration-induced damage in thin metallic film conductors generally occurs by the formation of voids and extrusions (hillocks) at grain boundaries. The origin of this damage, in particular void damage, has been studied theoretically by several investigators over the years. In these treatments, void formation has been analyzed in terms of classical nucleation from a supersaturated solution of vacancies. Although a supersaturation of vacancies undoubtedly exists in a film experiencing electromigration, the origin of these vacancies has yet to be adequately identified. Since electromigration-induced damage is an important cause of failure in semiconductor circuits, our investigation sought solutions to the problem. Recently, we proposed a model for electromigration-induced void formation where stress-induced vacancy generation at the grain boundaries supplies vacancies that diffuse into the neighboring lattice and leads to grain boundary thinning. This model could account for our transmission electron microscope observations as well as for the presence of compressive stresses and the absence of tensile stresses in films undergoing electromigration, as observed by Blech. In this paper we shall report further theoretical considerations on the problem of grain boundary vacancy generation and we shall also present a model for electromigration-induced damage where void and hillock growth is treated by an application of the well known Herring-Nabarro diffusive creep theory.
*Abstract of a paper presented at the International Conference on Metallurgical Coatings, San Francisco, CA, U.S.A., April 6-10, 1981. 0040-6090/81/0000-0000/$02.50
(C Elsevier Sequoia/Printed in The Netherlands