TY - JOUR
T1 - Confinement of electromigration induced void propagation in Cu interconnect by a buried Ta diffusion barrier layer
AU - Yan, M. Y.
AU - Tu, King-Ning
AU - Vairagar, A. V.
AU - Mhaisalkar, S. G.
AU - Krishnamoorthy, Ahila
PY - 2005/12/1
Y1 - 2005/12/1
N2 - Direct observation, by means of in situ scanning electron microscopy, of void heterogeneous nucleation and migration controlled electromigration failure mechanism in Cu dual damascene interconnect structures has been recently reported [A. V. Vairagar, S. G. Mhaisalkar, A. Krishnamoorthy, K. N. Tu, A. M. Gusak, M. A. Meyer, and E. Zschech, Appl. Phys. Lett. 85, 2502 (2004)] In the present study, a dual damascene structure with an additional 25 nm Ta diffusion barrier embedded into the upper Cu layer was fabricated. This thin layer of diffusion barrier blocked voids from propagating into the via, thus eliminating the previously reported failure mechanism. With this structure, a lifetime improvement of at least 40 times was achieved. Analysis on failed samples suggested that failures in samples with the embedded Ta barrier layer occurred at the bottom of the via, which were caused by void migration along the bottom of the Cu lines.
AB - Direct observation, by means of in situ scanning electron microscopy, of void heterogeneous nucleation and migration controlled electromigration failure mechanism in Cu dual damascene interconnect structures has been recently reported [A. V. Vairagar, S. G. Mhaisalkar, A. Krishnamoorthy, K. N. Tu, A. M. Gusak, M. A. Meyer, and E. Zschech, Appl. Phys. Lett. 85, 2502 (2004)] In the present study, a dual damascene structure with an additional 25 nm Ta diffusion barrier embedded into the upper Cu layer was fabricated. This thin layer of diffusion barrier blocked voids from propagating into the via, thus eliminating the previously reported failure mechanism. With this structure, a lifetime improvement of at least 40 times was achieved. Analysis on failed samples suggested that failures in samples with the embedded Ta barrier layer occurred at the bottom of the via, which were caused by void migration along the bottom of the Cu lines.
UR - http://www.scopus.com/inward/record.url?scp=29744458580&partnerID=8YFLogxK
U2 - 10.1063/1.2158030
DO - 10.1063/1.2158030
M3 - Article
AN - SCOPUS:29744458580
VL - 87
SP - 1
EP - 3
JO - Applied Physics Letters
JF - Applied Physics Letters
SN - 0003-6951
IS - 26
M1 - 261906
ER -