Evidence of ultra-low-k dielectric material degradation and nanostructure alteration of the Cu/ultra-low-k interconnects in time-dependent dielectric breakdown failure

• Main Authors: Lam, Jeffrey C. K., Huang, Maggie Y. M., Ng, Tsu Hau, Mohammed Khalid Dawood, Zhang, Fan, Du, Anyan, Sun, Handong, Shen, Zexiang, Mai, Zhihong
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Science::Mathematics::Applied mathematics
• Online Access: https://hdl.handle.net/10356/96542; http://hdl.handle.net/10220/9881
• Institution: Nanyang Technological University

Ultra-low-k time-dependent dielectric breakdown (TDDB) is one of the most important reliability issues in Cu/low-k technology development due to its weaker intrinsic breakdown strength compared to SiO2 dielectrics. With continuous technology scaling, this problem is further exacerbated for Cu/ultra-low-k interconnects. In this letter, the TDDB degradation behavior of ultra-low-k dielectric in Cu/ultra-low-k interconnects will be investigated by a method consisting of a combination of Raman with Fourier transform infrared vibrational microscopes. In TDDB tests on Cu/low-k interconnect, it was found that intrinsic degradation of the ultra-low-k dielectric would first occur under electrical field stress. Upon further electrical field stress, the ultra-low-k dielectric degradation would be accelerated due to Ta ions migration from the Ta/TaN barrier bi-layer into the ultra-low-k dielectrics. In addition, no out-diffusion of Cu ions was observed in our investigation on Cu/Ta/TaN/ SiCOH structures.