Studies of cobalt thin films deposited by sputtering and MOCVD

Cobalt films were deposited on a Si wafer at substrate temperatures ranging from 50 to 200degreesC by metal-organic chemical vapor deposition (MOCVD) using Co-2(CO)(8) as a precursor. As-deposited MOCVD Co films contained low impurity contents and were obtained as a microcrystalline structure compared to sputtered Co films. After annealing at 400 degreesC, the resistivity of a 100 nm thick MOCVD Co film decreased to about 6 muOmega cm. This was similar to the resistivity of bulk Co and lower than that of a sputtered Co film. The decrease in resistivity coincides with grain growth in the Co film. In addition, annealing at 300 degreesC produced a stronger (0 0 2) fiber texture in the MOCVD Co film compared to a sputtered Co film. Grain growth appears to be coupled to the strong (002) texture evolution, possibly indicating that surface energy minimization can be a driving force for grain growth in MOCVD Co films. Formation of Co oxide inhibited grain growth and led to a high resistivity of the sputtered Co films. CoSi2 was formed in MOCVD Co films whereas Co2Si was formed in the sputtered Co films after annealing at 700 degreesC. (C) 2003 Elsevier Science B.V. All rights reserved.