The measured switched polarization properties of integrated Pb(Zr,Ti)O3 (PZT) capacitors arrays have been found to show a small dependence on individual capacitor size in the range from 0.17 and 100 μm2. These thin (90 nm) PZT capacitors have low voltage switching properties with polarization saturation of <1.8 V with switched polarization for the smallest capacitors (0.17 μm2) still larger than 25 μC/cm2. The capacitor stack consisted of TiAlN hardmask/Ir/IrOx/PZT/Ir/TiAlN on either SiO2 dielectric or W plugs. The capacitor was patterned using 248 nm lithography and etched using only one mask. For wafers without W plugs, the Ir bottom electrode was not etched. For wafers with W plugs, the entire capacitor stack was etched and electrical connection to the bottom electrode was through the W plugs. The capacitors were integrated using SiO2 dielectrics and one level of Al metallization. These data suggest that high-density, ferroelectric capacitor-based memories may be feasible.

MgAl2O4 films have been grown epitaxially on both Si(100) and MgO(lOO) by a novel single source metal-organic chemical vapor deposition (MOCVD) process. A single molecular source reagent [magnesium dialuminum isopropoxide, MgAl2(OC3H7)8] having the desired Mg: Al ratio was dissolved in a liquid solution and flash-vaporized into the reactor. Both thermal and plasma-enhanced MOCVD were used to grow epitaxial MgAl2O4 thin films. The Mg: Al ratio in the deposited films was the same as that of the starting compound (Mg: Al = 1:2) over a wide range of deposition conditions. The deposition temperature required for the formation of crystalline spinel was found to be significantly reduced and crystallinity was much improved on Si by using a remote plasma-enhanced MOCVD process. The epitaxial nature of the MgAI2O4 films was established by x-ray pole figure analysis.Magnesium aluminum spinel (MgAl2O4) is a promising electronic material with electrical and optical properties that have great technological importance.1"4 The combination of low dielectric constant (e = 7.5), low loss tangent (tan 5 = 4 X 10~4), and the close match of the oxygen ion lattice structure of MgAl2O4 with Si and a number of other important oxide systems makes MgAl2O4 particularly attractive for integrated electronic devices.5"7 The lattice parameters of spinel and several important oxides are listed in Table I. Both single crystal Si6 and GaAs7 have been epitaxially grown on (100) MgAl2O4 substrates. The epitaxial growth of perovskitetype oxides (PbTiO3, BaTiO3, and SrTiO3) on MgAl2O4coated Si has also been recently demonstrated.8'9MgAl2O4 thin films have been grown by a halogen CVD technique reacting metal chlorides with CO2 and H2 at elevated temperatures to give MgAl2O4, with CO and HC1 by-products.8 The main shortcoming of this halogen CVD technique is the high growth temperature (980 °C) needed to provide the activation energy to drive the reaction. The corrosive and toxic by-products are also strong deterrents for scaling-up this process. Metal-organic chemical vapor deposition (MOCVD) has been shown to be a promising technique for the fabrication of device quality compound semiconductors, high-Tc superconductors, and ferroelectric thin films.

Cerium oxide thin films were deposited on fused silica using atomic layer deposition (ALD). The novel Ce precursor, Ce(iPrCp)2(N-iPr-amd) [bis-isopropylcyclopentadienyl-di-isopropylacetamidinate-cerium] is a room-temperature liquid with good thermal stability and evaporates cleanly. Water vapor was used as the oxygen source. The growth characteristics and film properties of ALD CeO2 were investigated. A relatively broad ALD window of 165–285 °C resulted in a constant growth rate of 1.9 Å/cycle and good thickness uniformity. The films deposited at 240 °C were found to be polycrystalline with cubic structure without a preferential direction in as-deposited condition. However, films grown at 335 °C slightly favored a (200) preferred orientation. XPS analysis showed that films are free from contamination, and the Ce:O stoichiometry analysis revealed the existence of oxygen vacancies in the films with composition CeO1.74.

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