Leakage currents in Ba0.7Sr0.3TiO3 thin films for ultrahigh-density dynamic random access memories

(Ba,Sr)TiO3 (BST) thin films grown by chemical vapor deposition and with platinum (Pt) top and bottom electrodes have been characterized with respect to the leakage current as a function of temperature and applied voltage. The data can be interpreted via a thermionic emission model. The Schottky approximation accounts for superohmic behavior at higher fields, but the barrier lowering is stronger than expected from this theory. While the leakage mechanism is comparable to SrTiO3 thin films prepared by chemical solution deposition, the absolute values of the leakage current are significantly lower for the metalorganic chemical vapor deposition (MOCVD) prepared BST film. This is presumably due to a more homogeneous microstructure of the latter and may also be due to different electrode processing. The influence of the film thickness on the leakage in combination with additional findings is used to discuss the field distribution in the films under a dc voltage stress.

[1]  A. Sleight.  Ferroelectric thin films IV: By S.B. Desu, B.A. Tuttle, R. Ramesh, and T. Shiosaki (eds). Materials Research Society, Pittsburgh, 1995, 624 pages, price $59 MRS member, $69 US list, $74 foreign. ISBN 1-55899-262-6 , 1995 .

[2]  R. Waser,et al.  Electrode influence on the charge transport through SrTiO3 thin films , 1995 .

[3]  J. J. Lee,et al.  Electrode contacts on ferroelectric Pb(ZrxTi1−x)O3 and SrBi2Ta2O9 thin films and their influence on fatigue properties , 1995 .

[4]  V. Chivukula,et al.  Dielectric properties of ferroelectric thin films in the frequency range of mHz-GHz , 1995 .

[5]  J. Roeder,et al.  Manufacturing of perovskite thin films using liquid delivery MOCVD , 1995 .

[6]  Jun Hee Lee,et al.  Ferroelectric properties and reliability of La-Sr-Co-O/Pb-La-Zr-Ti-O/La-Sr-Co-O heterostructures on si for non-volatile memory applications , 1995 .

[7]  S. Dey,et al.  Electrical Properties of Paraelectric (Pb 0.72La 0.28)TiO3 Thin Films with High Linear Dielectric Permittivity: Schottky and Ohmic Contacts , 1995 .

[8]  R. Waser,et al.  How to analyse relaxation and leakage currents of dielectric thin films: Simulation of voltage-step and voltage-ramp techniques , 1995 .

[9]  D. Wouters,et al.  Elements of the leakage current of high-ε ferroelectric PZT films , 1995 .

[10]  R. Waser,et al.  Science and technology of electroceramic thin films , 1995 .

[11]  H. Noshiro,et al.  Influence of Electrode Contacts on Leakage Current of SrTiO3 Capacitors , 1994 .

[12]  Y. Fukuda,et al.  Current-Voltage Characteristics of Electron-Cyclotron-Resonance Sputter-Deposited SrTiO3 Thin Films , 1994 .

[13]  S. B. Krupanidhi,et al.  Current-voltage characteristics of ultrafine-grained ferroelectric Pb(Zr, Ti)O_3 thin films , 1994 .

[14]  T. Roberts,et al.  Dielectric breakdown in high-ε films for ULSI DRAMs: II. barium-strontium titanate ceramics , 1994 .

[15]  H. Gamo,et al.  Domains in ferroelectric VDF/TrFE copolymer thin films: Investigated by a new optical probe method , 1993 .

[16]  S. Komatsu,et al.  Dielectric Constant and Leakage Current of Epitaxially Grown and Polycrystalline SrTiO3 Thin Films , 1993 .

[17]  S. B. Krupanidhi,et al.  Structural and electrical characteristics of SrTiO 3 thin films for dynamic random access memory applications , 1993 .

[18]  R. Waser,et al.  Theory of conduction and breakdown in perovskite thin films , 1992 .

[19]  P. Joshi,et al.  Strontium titanate thin films by rapid thermal processing , 1992 .

[20]  S. Komatsu,et al.  Epitaxial growth of SrTiO3 films on Pt electrodes and their electrical properties , 1992 .

[21]  Chenming Hu,et al.  Electrical characteristics of ferroelectric PZT thin films for DRAM applications , 1992 .

[22]  R. Zuleeg,et al.  D.C. leakage currents in ferroelectric memories , 1992 .

[23]  R. Zuleeg,et al.  Quantitative measurement of space-charge effects in lead zirconate-titanate memories , 1991 .

[24]  G. Blatter,et al.  REVIEW ARTICLE: Electrical properties of grain boundaries in polycrystalline compound semiconductors , 1990 .

[25]  F. Michel-calendini,et al.  Absorption spectrum in the near U.V. and electronic structure of pure barium titanate , 1988 .

[26]  G. Dresselhaus,et al.  Surface defects and the electronic structure of SrTi O 3 surfaces , 1978 .

[27]  A. M. Glass,et al.  Principles and Applications of Ferroelectrics and Related Materials , 1977 .

[28]  K. Härdtl,et al.  Mobility determinations from weight measurements in solid solutions of (Ba, Sr) TiO3 , 1972 .

[29]  R. O. Bell,et al.  NONLINEARITY AND MICROWAVE LOSSES IN CUBIC STRONTIUM-TITANATE , 1961 .