Materials Chemistry and Physics 80 (2003) 560–564 Studies of cobalt thin films deposited by sputtering and MOCVD Y.K. Ko a , D.S. Park a , B.S. Seo a , H.J. Yang a , H.J. Shin a , J.Y. Kim a , J.H. Lee a , W.H. Lee a,1 , P.J. Reucroft b , J.G. Lee a,∗ a School of Metallurgical and Materials Engineering, Kookmin University, Seoul 136-702, South Korea b Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA Received 3 September 2002; received in revised form 9 December 2002; accepted 15 January 2003 Abstract Cobalt films were deposited on a Si wafer at substrate temperatures ranging from 50 to 200 ◦ C 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 ◦ C, the resistivity of a 100 nm thick MOCVD Co film decreased to about 6  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 ◦ C 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 (0 0 2) 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. CoSi 2 was formed in MOCVD Co films whereas Co 2 Si was formed in the sputtered Co films after annealing at 700 ◦ C. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Thin films; MOCVD; Sputtering; Annealing; Co films 1. Introduction Cobalt and cobalt-based thin films have attracted great in- terest for possible applications in data storage devices and sensors. Co films have been deposited by various methods such as thermal evaporation [1], electron beam evaporation [2–4], sputtering [5,6] and chemical vapor deposition [7]. Co films have also been deposited on Si by metal-organic chem- ical vapor deposition (MOCVD) in order to obtain CoSi 2 for metallization [8,9]. Chemical vapor deposition (CVD) of- fers several advantages in terms of good conformal coverage and high growth rates. MOCVD often provides additional advantages, such as lower substrate temperatures, compared to conventional CVD. Co films have been deposited by MOCVD [10–12] and physical vapor deposition. However, Co films deposited by these different processes have rarely been compared in terms of film properties and film/substrate interactions. In these comparison studies, Co films were deposited by MOCVD and sputtering methods. Since MOCVD is fundamentally ∗ Corresponding author. Tel.: +82-2-910-4667; fax: +82-2-910-4320. E-mail address: lgab@kookmin.ac.kr (J.G. Lee). 1 Present address: Department of Advanced Materials Engineering, Sejong University, Seoul 143-747, South Korea. different from physical vapor deposition processes such as sputtering, film properties and microstructure could be quite different in Co films produced by these two processes. Inter- actions between the film and the substrate in a post-annealing process is also expected to be different in the MOCVD and sputtered Co films. 2. Experimental Co films were deposited on a Si substrate by MOCVD and a sputtering method. A p-type 4 in. Si(1 0 0) wafer was charged into the MOCVD reaction chamber through a load-lock chamber to prevent air contamination. The Si substrate was heated from 50 to 200 ◦ C at a base pressure of 2 × 10 -6 Torr. Dicobalt octacarbonyl [Co 2 (CO) 8 ] was heated to 35 ◦ C and carried as a vapor phase precursor into the reaction chamber by Ar gas. The gas line was heated to 45 ◦ C to prevent condensation of the Co precursor. Co films were deposited at a vacuum pressure of 0.6Torr. Co films were also deposited on the Si substrate by a radio fre- quency magnetron sputtering method. Sputtered Co films were produced from a pure Co target. The sputtered Co films were deposited at a vacuum pressure of 2mTorr with a power of 120W. The Co film thickness deposited by both 0254-0584/03/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0254-0584(03)00085-3