TY - JOUR
T1 - Characterization of electroless deposited Co (W,P) thin films for encapsulation of copper metallization
AU - Kohn, A.
AU - Eizenberg, M.
AU - Shacham-Diamand, Y.
AU - Sverdlov, Y.
N1 - Funding Information:
The work was supported by grant no. 8460-1-98 from the Israeli Ministry of Science and Technology. Thanks to A. Berner for assistance in EDS measurements, R. Brener for AES measurements, M. Oxman for the seed layer preparation and A. Sapir for TEM sample preparation.
PY - 2001/4/15
Y1 - 2001/4/15
N2 - Thin Co(W,P) films, 100-200 nm thick, were electroless deposited on oxidized silicon wafers using sputtered copper or cobalt as catalytic seed layers. The purpose of these films is to encapsulate copper preventing its corrosion or to serve as a diffusion barrier against copper contamination of silicon oxide and silicon in ULSI interconnect and packaging applications. The electroless cobalt layers were integrated with electroless copper and found to function as barriers up to a temperature of 500°C. The microstructure of the barrier film was found to consist of grains of h.c.p. cobalt, ∼ 10 nm in diameter, in which the grain boundaries are most probably enriched by phosphorus and tungsten. It was found that the phosphorus and tungsten impurities stabilize the h.c.p. phase, postponing the transition to the f.c.c. phase by more than 80°C, compared to pure bulk cobalt. The observed good barrier properties can be explained by the nano-sized grains along with the blocking effect of the impurities at the fast diffusion path of the grain boundaries. An advantage of these layers, relative to alternative diffusion barriers for copper, is their low electrical resistivity, 40 uΩ cm.
AB - Thin Co(W,P) films, 100-200 nm thick, were electroless deposited on oxidized silicon wafers using sputtered copper or cobalt as catalytic seed layers. The purpose of these films is to encapsulate copper preventing its corrosion or to serve as a diffusion barrier against copper contamination of silicon oxide and silicon in ULSI interconnect and packaging applications. The electroless cobalt layers were integrated with electroless copper and found to function as barriers up to a temperature of 500°C. The microstructure of the barrier film was found to consist of grains of h.c.p. cobalt, ∼ 10 nm in diameter, in which the grain boundaries are most probably enriched by phosphorus and tungsten. It was found that the phosphorus and tungsten impurities stabilize the h.c.p. phase, postponing the transition to the f.c.c. phase by more than 80°C, compared to pure bulk cobalt. The observed good barrier properties can be explained by the nano-sized grains along with the blocking effect of the impurities at the fast diffusion path of the grain boundaries. An advantage of these layers, relative to alternative diffusion barriers for copper, is their low electrical resistivity, 40 uΩ cm.
KW - Diffusion barrier
KW - Electroless deposition
KW - Interconnects
UR - http://www.scopus.com/inward/record.url?scp=0035871481&partnerID=8YFLogxK
U2 - 10.1016/S0921-5093(00)01348-4
DO - 10.1016/S0921-5093(00)01348-4
M3 - 文章
AN - SCOPUS:0035871481
SN - 0921-5093
VL - 302
SP - 18
EP - 25
JO - Materials Science and Engineering: A
JF - Materials Science and Engineering: A
IS - 1
ER -