Adhesion and Cu Diffusion Barrier Properties of a MnO x Barrier Layer Formed with Thermal MOCVD
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1156-D04-10
Adhesion and Cu diffusion barrier properties of a MnOx barrier layer formed with thermal MOCVD K. Neishi1, V. K. Dixit1, S. Aki1, J. Koike1 K. Matsumoto2, H. Sato2, H. Itoh2, S. Hosaka2 1 Department of Material Science, Tohoku University, Sendai 980-8579, Japan 2 Technology Development Center, Tokyo Electron Ltd., Nirasaki, 407-0192, Japan
Abstract A thin and uniform manganese oxide layer was formed below 400 oC by thermal chemical vapor deposition (CVD) on a tetraethylorthosilicate (TEOS) oxide substrate. No Cu delamination were observed both in the as-deposited and in the annealed PVD-Cu/CVD-MnOx/TEOS samples deposited below 300 oC, meanwhile the Cu films were delaminated from the CVD-MnOx/TEOS substrates deposited at 400 oC. From the results of XPS, Raman and SIMS analysis, a major reason for degradation of the adhesion properties is considered to be amount of carbon inclusion in the CVD Mn oxide layer. Introduction With the increase in packing density of ultra-large scale integrated circuits, geometrical dimensions continue to decrease. As the width of Cu line becomes narrow, the thickness of a barrier layer should be reduced to prevent the increase of the effective resistivity of the interconnect lines [1]. The barrier layer formation with a physical vapor deposition (PVD) technique has become difficult as the technology node is reduced to 45 nm because of poor step coverage. Chemical vapor deposition (CVD) has been known for its good step coverage, and is a candidate technique for the formation of a barrier layer, a Cu seed layer and entire Cu line. In our previous research, we investigated the formation behavior of manganese oxide layer with thermal CVD and the diffusion barrier properties of the oxide [2,3]. The thin and uniform amorphous MnOx layer could be formed on a blanket TEOS substrate as well as in a contact-hole structure and a dual damascene structure. Transmission electron microscopy indicated a good diffusion barrier property after annealing at 400 oC for 100 h. In addition to the reported properties, a good adhesion strength is necessary between a Cu line and a dielectric layer not only to ensure good SM and EM resistance but also to prevent film delamination under mechanical or thermal stress conditions during fabrication process such as chemical mechanical polishing or high temperature annealing. To date, no information is available with regard to the adhesion property of CVD-MnOx barrier layer. In this work, we investigated adhesion and diffusion barrier properties in further detail using X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS) and Raman spectroscopy. The dependence of the adhesion property on deposition temperature was correlated with the chemical composition and valence state of Mn and with the amount of carbon contained in the MnOx layer. Experimental procedures Substrates were p-type Si wafers having plasma TEOS oxide of 100nm in thickness. Bisethylcylopentadienyl manganese (EtCp)2Mn was used as a metal organic manganese
precursor. Th
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