Dependence of Ferroelectric Properties of SBT Based Capacitors on the Electrode Material

1998 ◽  
Vol 541 ◽  
Author(s):  
S. Tirumala ◽  
S. O. Ryu ◽  
K. B. Lee ◽  
R. Vedula ◽  
S. B. Desu
Keyword(s):  
Thin Films ◽  
Electrode Material ◽  
Electrode Materials ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Si Substrates ◽  
Non Volatile Memory ◽  
Metal Organic ◽  
Sputter Deposited ◽  
Memory Applications

AbstractThe effect of various electrode materials on the ferroelectric properties of SrBi2Ta2O9 (SBT) thin films has been investigated for non-volatile memory applications. Two sets of electrode structures, viz., Pt-Ir based and Pt-Rh based, were sputter deposited in-situ on Si substrates. SBT thin films were deposited on these electrodes using a metal-organic solution deposition technique followed by a post-deposition anneal at 750 °C in oxygen. Structural characterization revealed a polycrystalline nature with predominant perovskite phase in SBT thin films. Ferroelectric properties were studied in capacitor mode by depositing top electrodes, where the top electrode material is identical to that of the bottom electrode. Extensive analysis of the ferroelectric properties signify the important role played by the electrode material in establishing the device applicability is reported in this work.

Effects of Sputter-Deposited LaNiO3 Electrode on the Deposition and Properties of Ferroelectric Thin Films

1996 ◽  
Vol 433 ◽  
Author(s):  
T. B. Wu ◽  
J. M. Wu ◽  
C. M. Wu ◽  
M. J. Shyu ◽  
M. S. Chen ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Perovskite Phase ◽  
Sol Gel ◽  
Processing Condition ◽  
Fatigue Property ◽  
Rf Magnetron Sputtering ◽  
Ferroelectric Films ◽  
Si Substrates ◽  
Sputter Deposited

AbstractHighly (100)-textured thin film of metallic LaNiO3 (LNO) was grown on the Pt/Ti/SiO2/Si substrates by rf magnetron sputtering at ˜300°C, which was used as a bottom electrode to prepare highly (100)-textured ferroelectric films. Examples on the deposition of PbTiO3, (Pbl−xLax)TiO3, Pb(Zr0.53Ti0.47)O3, Pb[(Mg1/3Nb2/3)1−xTix]O3, and (Ba1−xSrx)TiO3 thin films by rf magnetron sputtering or sol-gel method are shown. A reduction of temperature for perovskite phase formation can be achieved, especially for those difficult to crystallize. The surface roughness of the ferroelectric films is also improved as compared to that of films deposited on conventional Pt electrode. Although the electrical properties of the ferroelectric films are affected by the out-diffusion of LNO when a higher temperature was used in the preparation of the films, under an appropriate processing condition, the highly (100)-textured films can have satisfactory electrical characteristics for application. Moreover, the polarization-fatigue property can be also improved by the use of LNO electrode.

Ferroelectric Properties of SBT (Sr/Bi/Ta = 0.8/2.3/2) Thin Films Using a Novel Chemical Solution Deposition

1998 ◽  
Vol 541 ◽  
Author(s):  
Seung-Hyun Kim ◽  
D.J. Kim ◽  
S.K. Streiffer ◽  
J-P. Maria ◽  
Angus I. Kingon
Keyword(s):  
Thin Films ◽  
Low Voltage ◽  
Ferroelectric Properties ◽  
Chelating Agent ◽  
Chemical Route ◽  
Solution Deposition ◽  
Appreciable Change ◽  
Non Volatile Memory ◽  
Memory Applications ◽  
Voltage Saturation

AbstractA new chemical route using an alkanolamine chelating agent for synthesis of ferroelectric Sro0.8Bi2.3Ta2O9 (SBT) thin films is investigated. The addition of alkanolamine provided stability to the SBT solution by retarding the hydrolysis and condensation rates. This solution could be stored for 30 days without any appreciable change of the properties. The crystallinity and the microstructure of the SBT thin films improved with increasing annealing temperature, and strongly influenced the ferroelectric properties. This alkanolamine modified films annealed at 800 °C exhibited low voltage saturation, high remanent polarization and resistance to fatigue after 1010 switching cycles. These electrical properties are favorable for non-volatile memory applications.

Preparation and Characterization of Ba and Nb Substituted SrBi2Ta2O9 Compounds

2000 ◽  
Vol 655 ◽  
Author(s):  
Rasmi R. Das ◽  
P. S. Dobal ◽  
A. Dixit ◽  
W. Perez ◽  
M.S. Tomar ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Phase Formation ◽  
Perovskite Phase ◽  
Growth Conditions ◽  
Layered Perovskite ◽  
Phonon Modes ◽  
Si Substrates ◽  
Non Volatile Memory ◽  
Lower Temperature ◽  
Memory Applications

AbstractBi-layered ferroelectric compounds are considered most promising for non-volatile memory applications due to their high fatigue endurance. We have prepared SrBi2Ta2O9 powders with Ba (A sites) and Nb (B sites) substitutions using a novel solution based route. The powders were pressed and sintered at 1050°C to obtain high quality targets. Thin films were prepared using these ceramic targets on Pt/TiO2/SiO2/Si substrates using pulsed laser deposition (PLD) technique. The effects of growth conditions on phase formation as well as structural and electrical properties in films are studied. Initial results on films show good hysteretic characteristics. Though phase formation begins at much lower temperature, these films crystallize in a complete layered perovskite phase when prepared at 700°C. Optical phonon modes in these materials exhibit systematic variations with changing compositions. The changes in the Raman spectra are explained in terms of Ba and Nb substitutions at A and B sites, respectively. The temperature dependence of Raman spectra exhibits the substitution induced changes in the transition temperatures of these materials.

Effect of Bottom Electrode System on Ferroelectric Properties of Sputter Deposited PZT Capacitors

1998 ◽  
Vol 541 ◽  
Author(s):  
Kwon Hong ◽  
Yong Sik Yu ◽  
Shang Kyoo Lee
Keyword(s):  
Bottom Electrode ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Electrode System ◽  
Fatigue Properties ◽  
Si Substrates ◽  
Pzt Films ◽  
Current Characteristics ◽  
Sputter Deposited ◽  
Electrode Systems

AbstractRF magnetron sputter deposited PZT films were prepared on various bottom electrode systems such as Pt/Ti/SiO2/Si, IrO2/SiO2/Si, Pt/IrO2/SiO2/Si and Ir/IrO2/SiO2/Si substrates using the ceramic PZT target with Pb1.1(Zr0.52Ti0.48)O3 composition. In order to obtain single perovskite phase, PZT films were sputter-deposited at room temperature under Ar only plasma condition followed by high temperature annealing under oxygen ambient. Regardless of the bottom electrode system, reasonable ferroelectric properties such as 2Pp, Vc could be obtained by 650°C post annealing. Their values were over 20μ C/cm2 and below ± 1.OV when drive voltage was ± 3V, respectively. Hybrid electrode system, namely, thick Pt or Ir and thin IrO2 shows good leakage current characteristics, of ∼ 10−8A/cm2. Fatigue properties of PZT capacitor depend on the test condition. However, retention after 3×104sec showed a degradation of 15% when writing voltage was −5V irrespective of bottom electrode system. Imprint characteristics also showed good results within ± 1 as a figure of merit (FOM).

Ferroelectric Thin Films Via Sol-Gel Processing of Singlesource Precursors

1993 ◽  
Vol 310 ◽  
Author(s):  
C.D. Chandler ◽  
M.J. Hampden-Smith ◽  
R.W. Schwartz
Keyword(s):  
Thin Films ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Dip Coating ◽  
Mixed Metal Oxide ◽  
Mixed Metal ◽  
Oxide Powders ◽  
Metal Organic ◽  
Gel Processing

AbstractThe use of single-source mixed metal-organic precursors specifically designed for the formation of crystalline perovskite phase mixed metal oxide powders has been investigated. Pyridine solutions of divalent metal α-hydroxycarboxylates of general empirical formula A(O2CCMe2OH)2 where A = Pb, Ca, Sr, Ba; Me = methyl, were designed to react with metal alkoxides, for example, Ti(O-i-Pr)4, with the elimination of two equivalents of alcohol to form species with fixed A:B stoichiometry of 1:1 according to the equation: A(O2CCMe2OH)2 + B(OR)4 → A(O2CCMe2O)2B(OR)2 + 2HOR. Hydrolysis of these compounds in pyridine produces clear solutions which on removal of the solvent in vacuo, yield yellow powders. These powders readily dissolve in ethanol to give solutions from which thin films can be formed either by dip-coating or spin coating. The crystallization behavior, composition and ferroelectric properties of these films is discussed. The crystallization of the films generally required substantially higher temperatures compared to powders obtained from the same precursor solutions.

Issues in the Flexible Integration of Sputter-Deposited PZT Thin Films with Polysilicon and Ti/Pt Electrode Layers for Use as Sensors and Actuators in Microelectromechanical Systems (MEMS)

2000 ◽  
Vol 657 ◽  
Author(s):  
C.F. Knollenberg ◽  
T.D. Sands ◽  
A.S. Nickles ◽  
R.M. White
Keyword(s):  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Microelectromechanical Systems ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Pt Electrode ◽  
Electrode Layer ◽  
Pzt Thin Films ◽  
Pzt Films ◽  
Sputter Deposited

ABSTRACTSputter-deposited piezoelectric lead zirconate titanate (PZT) thin films with Ti/Pt and polysilicon electrode layers are being investigated for use in Microelectromechanical Systems (MEMS). Existing research shows the nucleation of the perovskite phase of the PZT is linked to the lattice spacing of the underlying Pt electrode and/or seed layers, and is key in obtaining PZT layers with good piezoelectric/ferroelectric properties. Our research with piezoelectric PZT films on Ti/Pt electrode layers aims at employing these films to generate and receive acoustic waves in flexural plate wave devices (FPWs). Our experiments indicate the formation of a random polycrystalline perovskite phase is linked to the emergence of oriented <100> Pt grains within the dominant <111>-oriented crystal structure during rapid thermal annealing in an oxygen environment. Pt films annealed in nitrogen, in contrast, retained their <111> preferential orientation without the formation of Pt <100> grains. PZT films deposited on these electrodes and annealed in nitrogen were strongly oriented in the <111> direction, but exhibited lossy ferroelectric behavior and were prone to delamination. We are also investigating the feasibility of using doped polysilicon electrode layers with PZT thin films. The multiple layers used with the Pt electrode (Pt, Ti, and SiO2 adhesion layer) have significant interactions with one another, and replacing these layers with a single electrode layer should alleviate these complications. A low-temperature PZT deposition process (300°C) and short annealing cycles (30 sec.), coupled with a TiO2 barrier/seed layer should prevent interdiffusion and reactions between the polysilicon and PZT layers. Our experiments show that PZT films deposited and annealed on doped polysilicon layers develop a random polycrystalline perovskite phase, but are subject to tensile cracking. The use of polysilicon as an electrode layer should also facilitate the integration of piezoelectric PZT layers with polysilicon surface micromachined structures using SiGe sacrificial layers.

Dielectric and Ferroelectric Characterization of Sol-Gel Derived Ca-Doped PbTiO3 Thin Films

1996 ◽  
Vol 433 ◽  
Author(s):  
G. Teowee ◽  
K.C. McCarthy ◽  
E.K. Franke ◽  
J.M. Boulton ◽  
T.P. Alexander ◽  
...  
Keyword(s):  
Thin Films ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Test System ◽  
Impedance Analyzer ◽  
Si Substrates ◽  
Phase Development ◽  
Pt Electrodes

AbstractA series of sol-gel derived CaTiO3- PbTiO3 thin films ( i.e. Pb1−xCaxTiO3 with x = 0 − 1) was prepared on platinized Si substrates and fired to temperatures ranging from 550C to 650C. Multiple spincoating was performed to obtain films up to 0.5 μm thick with an intermediate firing of 400C between coatings. After the final crystallization firing, top Pt electrodes were sputtered to form monolithic capacitors. These capacitors were subjected to dielectric and ferroelectric characterization using an impedance analyzer and Radiant Technology RT66A Ferroelectric Test System. XRD was used to study the phase development and phase assembly of the fired films. All compositions were single perovskite phase after firing to 600C. The effects of Ca content on the crystallization behavior and ferroelectric properties are discussed.

Synthesis and Ferroelectric Properties of Sol–Gel Derived Intergrowth-Superlattice-Structured SrBi4Ti4O15-Bi4Ti3O12 Thin Films

2011 ◽  
Vol 197-198 ◽  
pp. 1781-1784
Author(s):  
Hua Wang ◽  
Jian Li ◽  
Ji Wen Xu ◽  
Ling Yang ◽  
Shang Ju Zhou
Keyword(s):  
Thin Films ◽  
Remanent Polarization ◽  
Annealing Temperature ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Hysteresis Loops ◽  
Si Substrates ◽  
Gel Processing ◽  
Coercive Electric Field ◽  
Clockwise Hysteresis

Intergrowth-superlattice-structured SrBi4Ti4O15–Bi4Ti3O12(SBT–BIT) films prepared on p-Si substrates by sol-gel processing. Synthesized SBT–BIT films exhibit good ferroelectric properties. As the annealing temperature increases from 600°C to 700°C, the remanent polarization Prof SBT–BIT films increases, while the coercive electric field Ecdecreases. SBT–BIT films annealed at 700°C have a Prvalue of 18.9µC/cm2which is higher than that of SBT (16.8µC/cm2) and BIT (14.6µC/cm2), and have the lowest Ecof 142 kV/cm which is almost the same as that of SBT and BIT. The C-V curves of Ag/SBT-BIT/p-Si heterostructures show the clockwise hysteresis loops which reveal the memory effect due to the polarization. The memory window in C-V curve of Ag/SBT-BIT/p-Si is larger than that of Ag/SBT/p-Si heterostructure or Ag/BIT/p-Si heterostructure.

Ferroelectric C-Axis Oriented Pb5Ge3O11 Thin Films for One Transistor Memory Application

1998 ◽  
Vol 541 ◽  
Author(s):  
Tingkai Li ◽  
Fengyan Zhang ◽  
Sheng Teng Hsu
Keyword(s):  
Thin Films ◽  
Ferroelectric Properties ◽  
Hysteresis Loops ◽  
Chemical Vapor ◽  
Dielectric Constants ◽  
Memory Devices ◽  
Leakage Currents ◽  
Fatigue Characteristics ◽  
Ferroelectric Memory ◽  
Memory Applications

AbstractOne transistor memory devices have been proposed recently. To meet the needs of one transistor memory applications, C-axis oriented Pb5Ge3O11 (PGO) thin films were prepared using metalorganic chemical vapor deposition (MOCVD) and rapid thermal processing (RTP). It was found that the nucleation of C-axis Pb5Ge3O11 phase started at a deposition temperature below 400°C and grain growth dominated at 500°C or above. With increasing annealing temperature, the remanent polarization (Pr) and coercive field (Ec) values increased, and the hysteresis loops of the Pb5Ge3O11 films were well saturated and symmetrical after the post-annealing. The C-axis PGO thin film showed good ferroelectric properties at 5V: 2Pr and 2Ec values were 2.0 - 4.0 µC/cm2 and 90 - 110 kV/cm, respectively. The films also showed excellent fatigue characteristics: no fatigue was observed up to 1 × 109 switching cycles. The retention and imprint properties have also been studied. The leakage currents of the PGO films were 2 - 5 × 10−7 A/cm2 at 100 kV/cm and dielectric constants were 40 - 70. The high quality MOCVD Pb5Ge3O11 films can be used for single transistor ferroelectric memory devices.

Post-Processing of Pulsed Laser-Deposited Pzt Thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
C. K. Chiang ◽  
W. Wong-Ng ◽  
L. P. Cook ◽  
P. K. Schenck ◽  
H. M. Lee ◽  
...  
Keyword(s):  
Thin Films ◽  
Amorphous Material ◽  
Ferroelectric Properties ◽  
Pulsed Laser ◽  
Linear Shrinkage ◽  
Laser Deposition ◽  
Amorphous Films ◽  
Pzt Thin Films ◽  
Si Substrates ◽  
Pzt Thin Film

AbstractPZT thin films were prepared by pulsed laser deposition on unheated Ptcoated Si substrates. As deposited, the films were amorphous. Films crystallized at 550 - 600 °C to produce predominantly crystalline ferroelectric PZT. Crystallization of the amorphous material was accompanied by a linear shrinkage of ∼2 %, as manifested in development of cracks in the film. Spacing, width and morphology of larger cracks followed a regular progression with decreasing film thickness. For film thicknesses less than 500 runm, much of the shrinkage was taken up by small, closely-spaced cracks of local extent. Implications for measurement of PZT thin film ferroelectric properties and processing are discussed.

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