Study of a new electromigration failure mechanism by novel test structure

Author

Chen, L.D. ; Lin, B.L. ; Hsieh, M.H. ; Chang, C.W. ; Tsai, J.S. ; Peng, J.C. ; Chiu, C.C. ; Lee, Y.-H.

Author_Institution

TQRD, Taiwan Semicond. Manuf. Co., Ltd., Hsinchu, Taiwan

fYear

2015

fDate

19-23 April 2015

Abstract

A novel electromigration (EM) structure is designed and characterized with advanced Cu/low-k technology. Comparing the EM results derived from novel and traditional test structures, a new EM failure mechanism is proposed. The new mechanism is caused by the Cu/barrier interface damage at the metal line-edge during upper Via opening process. This damage provides a fast diffusion path. From the downstream EM test, it is observed that the thicker Ta-based ALD barrier has a higher activation energy and median time to failure compared to thinner Ta based barrier. Thicker barrier process enhances Cu/barrier adhesion and hence prevent the via opening induced interface damage.

Keywords

atomic layer deposition; copper; electromigration; failure analysis; integrated circuit reliability; low-k dielectric thin films; tantalum; EM failure mechanism; EM structure; activation energy; advanced copper-low-k technology; copper-barrier adhesion; copper-barrier interface damage; downstream EM test; electromigration failure mechanism; fast diffusion path; induced interface damage; median time-to-failure; metal line-edge; tantalum-based ALD barrier; test structure; via opening process; Adhesives; Electromigration; Failure analysis; Metals; Reliability; Stress; ALD barrier thickness; Cu interconnect; electromigration; failure mechanism; test structure;

fLanguage

English

Publisher

ieee

Conference_Titel

Reliability Physics Symposium (IRPS), 2015 IEEE International

Conference_Location

Monterey, CA

Type

conf

DOI

10.1109/IRPS.2015.7112684

Filename

7112684