Copper and Copper Oxide Thin Films Obtained by Metalorganic Microwave Plasma Cvd

Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) is an innovative technique allowing the direct preparation, at low temperature, of different valence states of copper (Cu°, Cu, Cu). The precursor used is a volatile metalorganic one (copper acetylacetonate) with helium as a carrier gas. The precursor is then transported in a remote plasma of Ar, A1/O2 or A r / ^ O gas at low pressure. A judicious choice of the process parameters microwave power, substrate temperature and nature of the oxidant gas (N2O or O2)allows to favour the formation of metallic copper, Q12O or CuO. Copper and its oxides have been deposited as thin films on silicon and magnesium oxide single crystals. The techniques used for the characterization of the as deposited polycrystalline films are X-ray diffraction, Auger Electron Spectroscopy and Scanning Electron Microscopy. IINTRODUCTION The discovery of high temperature superconductors in the systems La-Cu-O, Y-Ba-Cu-O, Bi-Sr-Cu-O and Tl-Ba-Ca-Cu-O has initiated some important research on single oxide phases. As copper oxide is found in all high Tc superconductors, copper (II) oxide thin layers can be considered as good models for studies directed towards the improved formation of thin films of the copper oxide based high Tc superconductors [1]. Among the techniques used for copper and copper oxide deposition, one can distinguish : spray pyrolysis of a salt solution [2], RF sputtering of copper and copper oxides [3], metal organic Chemical Vapor Deposition [4], plasma enhanced CVD [5] and laser CVD [6]. The purpose of this work was to use a method able to lead to copper and copper oxides thin layers at low temperature. A new technique has been investigated : metalorganic microwaves plasma enhanced chemical vapor deposition (MOMPECVD). Microwave plasmas was initially employed for semi-conductor etching [7], but the technique has also been developed for thin film deposition. Among the various materials prepared, one can mention diamond [8] and even Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jp4:1991247 C2-390 JOURNAL DE PHYSIQUE IV YBaCuO superconductors [9]. In this study, this innovative technique has been used for the synthesis of copper and copper oxides thin films from volatile organometallic precursors.