Residual Stress in Pzt Thin Films and its Effect on Ferroelectric Properties

1991 ◽  
Vol 243 ◽  
Author(s):  
Terry J. Garino ◽  
Mark Harrington
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Dielectric Constant ◽  
Remanent Polarization ◽  
Coefficient Of Thermal Expansion ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
External Stress ◽  
Circular Section ◽  
Pzt Thin Films

AbstractThe residual stress in solution derived Pb(Zr.53Ti.47)o3, PZT 53:47, films was determined by measuring the bending of the substrate due to the stress. The substrate consisted of an oxidized (100) silicon wafer with 300 nm coating of platinum. In all cases the stress was tensile. Films fired at a temperature in the range where pyrochlore formation occurs (500° to 575°C) had the highest residual stresses, 200 to 350 MPa, whereas those fired at higher temperatures, 600° to 650°C, where the perovskite phase forms had stresses of 100 to 200 MPa. Stress measurements made during film firing indicate that the pyrochlore containing films had higher residual stress because their coefficient of thermal expansion was much larger than that of predominantly perovskite films. The effect of the amount of stress on ferroelectric properties was studied by making measurements on a film with and without the application of an external stress. The external stress was applied by bending a circular section of the substrate, which effectively lowered the amount of tensile stress in the film by ∼30%. Decreasing the stress in this manner was found to increase the remanent polarization by ∼11% and the dielectric constant by ∼2%.

scholarly journals Robust ferroelectricity enhancement of PZT thin films by a homogeneous seed layer

2021 ◽  
Author(s):  
jie jiang ◽  
Lei Liu ◽  
Kuo Ouyang ◽  
Zhouyu Chen ◽  
Shengtao Mo ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Remanent Polarization ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Pzt Thin Films ◽  
Large Dielectric Constant ◽  
Sol Gel Process ◽  
A New Technique

Abstract With its excellent ferroelectric properties such as large dielectric constant and large remanent polarization, PZT thin films are extensively used in micro-sensors and other devices. In this study, the sol-gel process was used to fabricate Pb(Zr0.52Ti0.48)O3 thin films with Pb(ZrxTi1−x)O3 seed islands. The experimental consequences demonstrate that all the Pb(Zr0.52Ti0.48)O3 thin films with Pb(ZrxTi1−x)O3 seeds show pure perovskite phase with no other impurity phases, and the electrical properties of Pb(Zr0.52Ti0.48)O3 thin films modified by Pb(ZrxTi1−x)O3 seed islands with different Zr/Ti ratios are improved, such as remanent polarization increased, dielectric properties increased, coercive electric field decreased, leakage current density decreased, etc. In particular, the electrical properties of the Pb(Zr0.52Ti0.48)O3 thin films with Pb(ZrxTi1−x)O3 seed islands are the most optimal when the x is 0.52. This paper provides a new technique for optimizing the electrical properties of PZT thin films, which is of great significance for breaking through the bottleneck of the development of ferroelectric memory.

The Microstructure, Phase and Ferroelectric Properties of PZT Thin Films on Oriented Multilayer Electrodes

1999 ◽  
Vol 596 ◽  
Author(s):  
Tingkai Li ◽  
Sheng Teng Hsu ◽  
Yufei Gao ◽  
Mark Engelhard
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Hysteresis Loop ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Pyrochlore Phase ◽  
Experimental Results ◽  
Butyl Ether ◽  
Pzt Thin Films ◽  
Pzt Thin Film

AbstractThree kinds of oriented electrodes of Pt, Ir and Pt/Ir electrodes were prepared using electron beam evaporation techniques for deposition of PZT thin films. An oxide MOCVD reactor with liquid delivery system was used for the growth of PZT thin films. [Pb(thd)2], Zr(TMHD)4 and Ti(IPO)4 were dissolved in a mixed solvent of tetrahydrofuran or butyl ether, isopropanol and tetraglyme to form a precursor source. The deposition temperature and pressure were 500 - 650°C and 5 - 10 Torr, respectively. The experimental results showed PZT thin film deposited on various electrodes had different phase formation, microstructure and ferroelectric property. The X-ray patterns showed the perovskite phase of PZT was formed on both Ir and Pt/Ir electrodes at 550°C. The grain size of the PZT thin film increases after a further, higher temperature annealing. The as-deposited PZT thin film on Pt electrode exhibits pyrochlore phase at 550°C. The phase is transformed to perovskite phase after 650°C annealing. The experimental results also indicated that the MOCVD PZT thin film on Pt/Ir exhibits better ferroelectric and electrical properties compared to those deposited on Pt and Ir electrodes. A 300 nm thick PZT thin film on Pt/Ir electrode has a square, well saturated, and symmetrical hysteresis loop with 2Pr value of 40 μC/cm2 and 2Ec of 73 kV/cm at an applied voltage of 5 V. The hysteresis loop of the PZT thin film is almost saturated at 2 V. The leakage current of the film is 6.16 × 10−7 A/cm2 at 100 KV/cm. The electrode effects on ferroelectric properties of PZT thin films also have been investigated.

scholarly journals Solution Chemistry Optimization of Sol-Gel Processed Pzt Thin Films

1993 ◽  
Vol 310 ◽  
Author(s):  
Steven J. Lockwood ◽  
R. W. Schwartz ◽  
B. A. Tuitle ◽  
E. V. Thomas
Keyword(s):  
Thin Films ◽  
Acetic Acid ◽  
Remanent Polarization ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Solution Chemistry ◽  
Water Volume ◽  
Original Solution ◽  
Pzt Thin Films

AbstractWe have optimized the ferroelectric properties and microstructural characteristics of sol-gel PZT thin films used in a CMOS-integrated, 256 bit ferroelectric non-volatile memory. The sol-gel process utilized in our work involved the reaction of Zr n-butoxide, Ti isopropoxide, and Pb (IV) acetate in a methanol/acetic acid solvent system. A 10-factor screening experiment identified solution concentration, acetic acid addition, and water volume as the solution chemistry factors having the most significant effects on the remanent polarization, coercive field, ferroelectric loop quality, and microstruntural quality. The optimal values for these factors were determined by runnig a 3-factor uniform shell design, modelling the responses, and testing the models at the predicted optimal conditions. The optimized solution chemistry generated 3-layer, 300-400 nm thick films on RuO2 coated silicon substrates with coercive fields of less than 25 kV/cm (a 40-50 % improvement over the original solution chemistry), a remanent polarization of 25-30 μC/cm, and a reduction in the pyrochlore phase content below observable levels.

The Characterization and Electrical Properties of DOPED PZT Thin Films Prepared by Sol-Gel Processing

1994 ◽  
Vol 361 ◽  
Author(s):  
Wan In Lee ◽  
J.K. Lee ◽  
Elsub Chung ◽  
C.W. Chung ◽  
I.K. Yoo ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Remanent Polarization ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Current Level ◽  
Pzt Thin Films ◽  
Sol Gel Process ◽  
Pzt Films ◽  
Gel Processing

ABSTRACTPZT (Zr/Ti = 53/47), PNZT (4% Nb doped PZT), PSZT (2% Sc doped PZT), and PSNZT (1% Sc and 1% Nb doped PZT) thin films were prepared by a sol-gel process. They were characterized by XRD, SEM and TEM. Both crystallographic orientation and grain size of PZT films can be changed by doping. Pt/PZT/Pt capacitors were fabricated for the measurement of ferroelectric properties. By doping with both Sc and Nb, the fatigue performance of the PZT films was considerably improved and the coercive field was decreased, while the remanent polarization was not changed. In addition, the effect of dopants on the leakage current level of PZT films was studied.

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.

Laser-Assisted Low Temperature Processing of PZT Thin Films

1997 ◽  
Vol 493 ◽  
Author(s):  
Yongfei Zhu ◽  
Jinsong Zhu ◽  
Y. J. Song ◽  
S. B. Desu
Keyword(s):  
Thin Films ◽  
Low Temperatures ◽  
Laser Annealing ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Processing Temperature ◽  
Pzt Thin Films ◽  
Step Process ◽  
Pzt Films ◽  
One Step

ABSTRACTA novel method for lowering processing temperature of ferroelectric Pb(Zr1−xTix)O3 (PZT) thin films was developed utilizing a laser-assisted two-step process. In the first step, perovskite phase was initiated in the PZT films by subjecting the films to a fornace anneal at low temperatures in the range of 470 °C to 550 °C depending on the Zr/Ti ratio. Later, the films were laser-annealed (using krF excimer laser) at room temperature to grow the perovskite phase, and to improve microstructure and ferroelectric properties. It was found that this two-step process was very effective in producing excellent quality ferroelectric PZT films at low temperatures. It should be noted that although laser annealing of amorphous and/or pyrochlore films directly (one-step process) produces perovskite phase, the ferroelectric properties of these films, irrespective of the composition, were rather unattractive. Some possible reasons for the ineffectiveness of the one-step process were discussed.

Sol-Gel Derived Pb(Zn1/3Nb2/3)O3-PbTiO3 Thin Films

1997 ◽  
Vol 493 ◽  
Author(s):  
G. Teowee ◽  
K. C. McCarthy ◽  
F. S. McCarthy ◽  
D. G. Davis ◽  
J. T. Dawley ◽  
...  
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Firing Temperature ◽  
Remanent Polarization ◽  
Single Phase ◽  
Perovskite Phase ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Dissipation Factor ◽  
Pt Films

ABSTRACTA series of sol-gel derived PB(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) films, with various PbTiO3 contents, have been prepared on platinized Si wafers. The (l-x)PZN - xPT films fired to 700C became single phase perovskite for x > 0.7. In the PZN-0.1PT films, the films still contain pyrochlore phase at a firing temperature of 850C; the perovskite phase appeared at a firing temperature of 800C. The dielectric constant increased with increasing PT content, with a peak in dielectric constant at x = 0.8. PZN-PT films with x = 0.8 exhibited dielectric constant, dissipation factor, remanent polarization and coercive field values of 600, 0.10, 6 and 45 kV/cm respectively.

Effect of PLT Buffer Layers on the PZT Thin Films for Scaling-Down Ferroelectric Materials

2005 ◽  
Vol 902 ◽  
Author(s):  
Li Dong Hua ◽  
Eun Sun Lee ◽  
Hyun Woo Chung ◽  
Byung Du Ahn ◽  
Sang Yeol Lee
Keyword(s):  
Thin Films ◽  
Applied Voltage ◽  
Remanent Polarization ◽  
Ferroelectric Properties ◽  
Ferroelectric Materials ◽  
Buffer Layers ◽  
Pzt Thin Films ◽  
Si Substrates ◽  
Scaling Down ◽  
Hysteresis Characteristics

AbstractThe Hysteresis characteristics of below 400 nm- thick Pb(Zr0.52Ti0.48)O3 (PZT) thin films grown on Pt (111) /Ti/SiO2/Si substrates have showed very poor with remanent polarization of 1∼3 μC/cm2 in our previous research. To study the further scaling-down, we introduced the method of our previous research that the (Pb0.72La0.28)Ti0.94O3 (PLT) buffer layers play an important role in enhancing the ferroelectric properties of the PZT thin films. As a result, the remanent polarization of 300 nm-thick PZT thin films with the 10 nm-thick PLT buffer layers have showed 32 μC/cm2 at applied voltage of 8 V and 24 μC/cm2 at applied voltage of 5 V. Inserted the PLT seed layers between the PZT thin films and substrate, the hysteresis characteristics of PZT thin films were improved a lot. The dielectric and leakage current properties of PZT thin films were also investigated.

Effect of Pb Excess Content on Microstructure and Electrical Properties of Sol Gel Derived PZT Thin Films

1999 ◽  
Vol 596 ◽  
Author(s):  
Zhan-jie Wang ◽  
Ryutaro Maeda ◽  
Kaoru Kikuchi
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Lead Zirconate ◽  
Pzt Thin Films ◽  
Starting Solution ◽  
Pzt Films

AbstractLead zirconate titanate (PZT) thin films were fabricated by a three-step heat-treatment process which involves the addition of -10, 0 and 10 mol% excess Pb to the starting solution and spin coating onto Pt/Ti/SiO2/Si substrates. Crystalline phases as well as preferred orientations in PZT films were investigated by X-ray diffraction analysis (XRD). The microstructure and composition of the films were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA), respectively. The well-crystallized perovskite phase and the (100) preferred orientation were obtained by adding 10% excess Pb to the starting solution. It was found that PZT films to which 10% excess Pb was added had better electric properties. The remanent polarization and the coercive field of this film were 34.8 μC/cm2 and 41.7 kV/cm, while the dielectric constant and loss values measured at 1 kHz were approximately 1600 and 0.04, respectively. Dielectric and ferroelectric properties were correlated to the microstructure of the films.

Effect on Crystal Orientation on Residual Stress and Electrical Properties of a PZT Thin Film Deposited on Buffered-Si Substrate

2006 ◽  
Vol 320 ◽  
pp. 65-68
Author(s):  
Keisuke Fujito ◽  
Naoki Wakiya ◽  
Takanori Kiguchi ◽  
Nobuyasu Mizutani ◽  
Kazuo Shinozaki
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Electrical Properties ◽  
Tensile Stress ◽  
Remanent Polarization ◽  
Residual Tensile Stress ◽  
Si Substrate ◽  
Pzt Thin Films ◽  
Pzt Film ◽  
Pzt Thin Film

Changes of residual stress and electrical properties were examined in (001)-oriented and (111)-oriented Pb(Zr0.5Ti0.5)O3 (PZT) thin films deposited on a buffered-Si substrate with a buffer and bottom electrode layer of a (La,Sr)CoO3(LSCO). A (001)-epitaxial PZT film was prepared on LSCO/CeO2 /Zr0.85Y0.15O1.93(YSZ)/Si. In addition, a (111)-oriented PZT film was prepared on LSCO/SrTiO3(ST) /Mn0.24Zn0.09Fe2.67O4(MZF)/YSZ/Si. The residual tensile stress in (001)-PZT thin films decreased from 2.92 to 1.98 GPa and the remanent polarization increased from 7.5 to 41.7 @C/cm2 as the LSCO thickness increased. In (111)-PZT, the residual tensile stress decreased from 1.72 to 0.95 GPa and remanent polarization increased from 9.5 to 26.7 @C/cm2. The residual tensile stress of (111)-PZT was less than that of (001)-PZT. The remanent polarization in the 80 nm (111)-PZT was greater than that of the 60 nm (001)-PZT. In the 700-nm-thick PZT, the remanent polarization in (001)-PZT was greater than that in (111)-PZT.

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