Chemical solution deposition of copper thin films and integration into a multilayer capacitor structure Song Won Ko & Tanawadee Dechakupt & Clive A. Randall & Susan Trolier-McKinstry & Michael Randall & Azizuddin Tajuddin Received: 17 January 2008 / Accepted: 15 September 2008 / Published online: 9 October 2008 # Springer Science + Business Media, LLC 2008 Abstract Metallization layers with thicknesses well below a micron are needed for future generation multilayer ceramic devices such as capacitors and integrated passive components. In many cases, the limiting thickness for the electrode is governed by dewetting of the metals from the oxide surface. Therefore, thin, stable metallization layers with low electrical resistivities that can survive high processing temperatures are of interest for these applica- tions. For this purpose, Cu films prepared from 2- methoxyethanol-based solutions were developed using adhesion promoters such as Ti, Zn, and Zr. The solutions were spun onto BaTiO 3 /SiO 2 /Si or SiO 2 /Si substrates, pyrolyzed, and annealed in a reducing ambient. The microstructure of films prepared in this way was found to be uniform and continuous at thicknesses as low as 80 nm. Cu films modified with 15 mol% Zr had electrical resistivities of about 16–17 μΩ-cm after 500°C annealing and 5–6 μΩ-cm after annealing at 900°C in a reducing ambient. Keywords Cu film . Multilayer capacitors . Electrical resistivity 1 Introduction The drive toward high volumetric efficiency in capacitors is enabled by continuous reductions in the thicknesses of both the dielectric and metallization layers [1–4]. The state of the art in powder-based production methods for BaTiO 3 /Ni capacitors produces dielectric thicknesses of ∼0.6 to 0.8 μm. There is continued interest in further reducing layer thicknesses to increase the capacitor volumetric efficiency [5]. At present, the progress in reducing the dielectric thickness has proceeded faster than attempts to reduce the thickness of Ni-based electrodes. The net result is that it is becoming increasingly more difficult to increase capacitance volumetric efficiency in MLCs. One approach to continuing reduction of layer thick- nesses is use of thin films. There are several reports of high permittivity BaTiO 3 -based dielectric thin films on metal foils by chemical solution deposition. Clem and co-workers [6] reported that oriented (Ba,Sr)TiO 3 films on Ni foils had a dielectric constant over 1,000 and low dielectric loss up to 500 kV/cm. Permittivities of 1,000–2,000 were also reported by Nagata et al. and Dechakupt et al. for BaTiO 3 films on Ni foils [7, 8]. Ihlefeld et al. [9–11] described 600– 650 nm thick BaTiO 3 films on Cu foils with dielectric constants as high as 2,500–3,000. Therefore, thin film technology combined with base metal electrodes seems to be a promising approach for down-scaling thicknesses in embedded capacitors, multilayer ceramic capacitors (MLC) and integrated passive components. Low layer count thin film MLCs have been reported by a variety of researchers. Sakabe et al. [12] demonstrated a thin film MLC on an MgO substrate by alternative depositions of a (Ba,Sr)TiO 3 dielectric layer and Pt electrode using metalorganic chemical vapor deposition (MOCVD) and sputtering, respectively. The Pt deposition J Electroceram (2010) 24:161–169 DOI 10.1007/s10832-008-9551-x S. W. Ko(*) : T. Dechakupt : C. A. Randall : S. Trolier-McKinstry Materials Science and Engineering Department, Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA e-mail: STMcKinstry@psu.edu M. Randall : A. Tajuddin KEMET Electronics Corporation, 2835 KEMET way, Simpsonville, SC 29681, USA