Formation of Mn Oxide with Thermal CVD and its Diffusion Barrier Property Between Cu and SiO 2
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1079-N03-11
Formation of Mn Oxide with Thermal CVD and its Diffusion Barrier Property Between Cu and SiO2 Koji Neishi, Shiro Aki, Jun Iijima, and Junichi Koike Materials Science, Tohoku University, 6-6-11 Aoba, Aramaki, Aoba-ku, Sendai, 980-8579, Japan Abstract A manganese oxide layer was formed by thermal chemical vapor deposition(CVD) on a tetraethylorthosilicate (TEOS) oxide substrate. The thickness of the Mn oxide layer could be varied 2.6 to 10 nm depending on deposition temperature. Heat-treated samples of PVD Cu / CVD Mn oxide /SiO2 indicated no interdiffusion. The CVD Mn oxide was found to be a good diffusion barrier layer. Introduction With the increase in packing density of ultra-large scale integrated circuits, geometrical dimensions continue to decrease. As a width of Cu line becomes narrow, a thickness of a barrier layer should be reduced to prevent the increase of the effective resistivity of the interconnect lines [1]. Ta and TaN have been widely used as conventional barrier materials to prevent interdiffusion between Cu line and dielectric insulating layer. Physical vapor deposition (PVD) have been employed as a their deposition method. The barrier layer formation with a PVD technique has become difficult as the technology node is reduced to 45 nm Without using Ta and TaN, Koike and his colleagues reported the self-formation of a diffusion barrier by direct deposition of a Cu-Mn seed layer on a TEOS oxide substrate. The Mn oxide layer was self-formed at the interface by annealing at elevated temperatures and acted as an excellent barrier layer [2-4]. However, as in the case of the conventional Ta barrier, PVD deposition of the Cu-Mn seed layer will eventually encounter the difficulty in deposition in narrow trenches and vias. 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 order to take advantage of the excellent reliability of Mn oxide, Mn deposition with CVD as a barrier layer is expected to be very attractive process. Up to date, only a few works have been reported for CVD-Mn layer. Wen-bin et al. reported that the deposition of a metallic Mn layer occurs above the temperature of 410ºC [5]. Maruyama and Osaki reported that a Mn oxide layer forms above 250ºC [6]. However, it is desirable to form the Mn barrier layer with CVD at lower temperatures. In this work, as a first approach of Manganese-based barrier layer formation by CVD, we deposited Mn oxide films using a metal organic precursor by thermal CVD at low temperatures and investigated the formation behavior and diffusion barrier property of the Mn oxide films. Experimental procedures Substrates were p-type Si wafers having a plasma TEOS oxides of 100nm in thickness. Bisethylcylopentadienyl manganese (EtCp)2Mn was used as a metal organic manganese precursor. The Mn precursor was vaporized and introduced into the hot- wall reaction chamber with Ar or H2 carrier gas in the thermal-CVD process. The detailed process
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