TY - JOUR
T1 - The role of microstructure in nanocrystalline conformal Co 0.9 W 0.02 P 0.08 diffusion barriers for copper metallization
AU - Kohn, A.
AU - Eizenberg, M.
AU - Shacham-Diamand, Y.
N1 - Funding Information:
This work was supported by the “Magnet” Program of the Chief Scientist Office at the Israeli Ministry of Industry and Trade, Consortium of Emerging Dielectric and Conductor Technologies for the Semiconductor Industry. A.K. acknowledges the support of the Israel Ministry of Science Eshkol grant. We thank C. Cytermann for SIMS measurements and Applied Materials Inc., Santa Clara for supplying the trench structures and depositing the IMP-PVD layers.
PY - 2003/5/15
Y1 - 2003/5/15
N2 - Electroless deposition of diffusion barriers for Cu metallization is an attractive process as it is selective, deposits conformal films at a low temperature and enables seedless Cu deposition. We demonstrate electroless deposition of conformal, ultra-thin (∼10 nm thick) films of Co 0.9 W 0.02 P 0.08 . Electroless Co 0.9 W 0.02 P 0.08 is an effective barrier against Cu diffusion up to 450 °C as opposed to physical vapor deposited (PVD) Co, which is a poor barrier. In this study, the role of microstructure in determining the barrier properties is discussed. The microstructure of the as-deposited layers consists of nanocrystallites of hexagonal close-packed (hcp) Co and an amorphous CoWP component. The amorphous component crystallizes at approximately 290 °C to hcp Co. The orthorhombic Co 2 P phase nucleates at 420 °C, while the majority phase remains hcp Co. Since we have found that up to 450 °C there is no phase formation between Cu and the Co 0.9 W 0.02 P 0.08 film, we conclude that the mechanism of barrier failure is grain boundaries diffusion. The dependance of Cu grain boundary diffusivity on the microstructure is qualitatively demonstrated by comparing between electroless deposited Co 0.9 W 0.02 P 0.08 , Co 0.9 P 0.1 and PVD cobalt. Secondary ion mass spectrometry depth profile measurements were performed on the films after subjecting them to anneals at 400 °C resulting in type-C Cu grain boundary diffusion. The Cu diffusivity in the Co 0.9 W 0.02 P 0.08 film is lower than in Co 0.9 P 0.1 , and substantially lower than in PVD Co. The difference in Cu diffusivity is explained by varying degrees of grain boundaries' passivation due to the P and W alloying elements enriching the grain boundaries. This passivation effect is more pronounced in the Co 0.9 W 0.02 P 0.08 films.
AB - Electroless deposition of diffusion barriers for Cu metallization is an attractive process as it is selective, deposits conformal films at a low temperature and enables seedless Cu deposition. We demonstrate electroless deposition of conformal, ultra-thin (∼10 nm thick) films of Co 0.9 W 0.02 P 0.08 . Electroless Co 0.9 W 0.02 P 0.08 is an effective barrier against Cu diffusion up to 450 °C as opposed to physical vapor deposited (PVD) Co, which is a poor barrier. In this study, the role of microstructure in determining the barrier properties is discussed. The microstructure of the as-deposited layers consists of nanocrystallites of hexagonal close-packed (hcp) Co and an amorphous CoWP component. The amorphous component crystallizes at approximately 290 °C to hcp Co. The orthorhombic Co 2 P phase nucleates at 420 °C, while the majority phase remains hcp Co. Since we have found that up to 450 °C there is no phase formation between Cu and the Co 0.9 W 0.02 P 0.08 film, we conclude that the mechanism of barrier failure is grain boundaries diffusion. The dependance of Cu grain boundary diffusivity on the microstructure is qualitatively demonstrated by comparing between electroless deposited Co 0.9 W 0.02 P 0.08 , Co 0.9 P 0.1 and PVD cobalt. Secondary ion mass spectrometry depth profile measurements were performed on the films after subjecting them to anneals at 400 °C resulting in type-C Cu grain boundary diffusion. The Cu diffusivity in the Co 0.9 W 0.02 P 0.08 film is lower than in Co 0.9 P 0.1 , and substantially lower than in PVD Co. The difference in Cu diffusivity is explained by varying degrees of grain boundaries' passivation due to the P and W alloying elements enriching the grain boundaries. This passivation effect is more pronounced in the Co 0.9 W 0.02 P 0.08 films.
KW - Diffusion barrier
KW - Electroless deposition
KW - Interconnects
UR - http://www.scopus.com/inward/record.url?scp=0038241571&partnerID=8YFLogxK
U2 - 10.1016/S0169-4332(03)00116-8
DO - 10.1016/S0169-4332(03)00116-8
M3 - 文章
AN - SCOPUS:0038241571
SN - 0169-4332
VL - 212-213
SP - 367
EP - 372
JO - Applied Surface Science
JF - Applied Surface Science
IS - SPEC.
ER -