Maeder - Muralt - Sagalowicz - Setter PT & PZT on Pt & RuO2 1 / 5 In-situ sputter deposition of PT and PZT films on Platinum and RuO 2 electrodes T. Maeder, P. Muralt, L. Sagalowicz and N. Setter Laboratoire de Céramique, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland Original version: Microelectronic Engineering 29 (1-4), 177-180, 1995. http://hdl.handle.net/10.1016/0167-9317(95)00139-5 Abstract The in-situ growth of PbZr x Ti 1-x O 3 (PZT) and PbTiO 3 (PT) thin films by reactive sputter deposition has been investigated for applications with silicon substrates. In-situ deposition from three simultaneously operating magnetron sources was applied. At the selected growth temperature range (550-600 °C), self- stabilisation of lead composition by a large desorption rate of Pb on stoichiometric PZT surfaces has been observed. Interlayer mixing was found to be limited to a few monolayers. Both Pt and RuO 2 on Si-SiO 2 wafers were used as top and bottom electrodes. The type of bottom electrode, together with the lead flux and the presence of a bottom PT layer to help nucleate the growth of PZT, was found to have a marked influence on the crystallisation behaviour of the PZT films. Dielectric characterisation has been performed on the films, and the dependence on the deposition parameters is discussed. 1. Introduction Recently, films of ferroelectric ceramics such as PZT and PT have received considerable attention. Their dielectric, piezoelectric (PZT) and pyroelectric (PT) properties can be applied to the fabrication of integrated devices such as memories [1], micromechanical devices [2, 3], and infrared detector arrays. For memories, RuO 2 has emerged as an alternative bottom electrode to Pt, leading to better fatigue properties [4]. PZT films may be grown by various methods [5-7]. In this work, the films were grown by an in-situ (without post-anneal) reactive sputtering technique [8] on Si-SiO 2 wafers metallised with Pt and RuO 2 electrodes. Crystallisation of PZT is expected to depend on the bottom electrode. On Pt, it had been found [4, 9] that a thin (30 nm) seed PT layer could nucleate growth of PZT along <100>. For RuO 2 [10], a second phase, identified as lead ruthenate (Pb 2 Ru 2 O 7 ), was seen at the RuO 2 -PZT interface. Also, RuO 2 might not be stable at the low oxygen pressure (about 2 Pa), high temperature and plasma bombardment during PZT deposition. 2. Experimental 2.1. Bottom electrodes 4" Si wafers, covered with 1 µm of thermal oxide (SiO 2 ), were used as substrates. They were covered with a TiO 2 (adhesion layer) - Pt sequence [11] or TiO 2 -RuO 2 by sputtering at 550-600°C in a Nordiko 2000 chamber. Other information is given in table 1. 2.2. PT and PZT deposition The PT and PZT films were deposited in an in-situ multimagnetron reactive sputtering process (in the same Nordiko 2000) [8]. Typical parameters are given in [9, 12]. For PZT, in order to enhance crystallisation and orientation, a 30 nm thick seed Ti-rich layer was deposited prior to the main PZT deposition [4, 9].