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.

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 of Pb Content on the Fatigue Properties of D.C. Reactive Sputtering-Derived PZT Thin Films

2006 ◽  
Vol 326-328 ◽  
pp. 613-616
Author(s):  
Dae Jin Yang ◽  
Seong Je Cho ◽  
Jong Oh Kim ◽  
Won Youl Choi
Keyword(s):  
Lead Zirconate Titanate ◽  
Perovskite Phase ◽  
Fatigue Behavior ◽  
Ferroelectric Properties ◽  
Pyrochlore Phase ◽  
Reactive Sputtering ◽  
Lead Zirconate ◽  
Fatigue Properties ◽  
Pzt Thin Films ◽  
Pzt Films

Lead zirconate titanate (Pb(Zr0.48Ti0.52)O3 or PZT) films were grown on platinized silicon wafers (Pt/SiO2/Si) by d.c. reactive sputtering method with multi targets. The Pb content of PZT films has been widely recognized as affecting not only the phase formation and microstructure but also the dielectric and ferroelectric properties. Pb content of PZT films was controlled by the variation of Pb target current. The relation between Pb content and Pb target current was expressed as y=0.89x-11.09. The x and y are Pb target current and Pb content, respectively. The pyrochlore phase was transformed to perovskite phase as Pb content was increased. This phase transformation improved the ferroelectric properties of PZT films. In PZT films with perovskite phase, fatigue properties were not improved with excess Pb content. Fatigue properties of PZT films began to be fatigued after 106 switching cycles and coincided with the typical PZT fatigue behavior. Excess Pb content (Pb vacancy) did not affect the fatigue properties of PZT films.

EFFECT OF PRE-HEATING TEMPERATURE ON THE CHARACTERISTICS OF PZT THIN FILMS GROWN BY USING A TRIOL SOL–GEL ROUTE

2007 ◽  
Vol 14 (02) ◽  
pp. 229-234
Author(s):  
SARAWUT THOUNTOM ◽  
MANOCH NAKSATA ◽  
KENNETH MACKENZIE ◽  
TAWEE TUNKASIRI
Keyword(s):  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Heating Temperature ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Hysteresis Loops ◽  
Lead Zirconate ◽  
Pzt Thin Films ◽  
Pzt Films ◽  
Ferroelectric Hysteresis

Lead zirconate titanate (PZT) films with compositions near the morphotropic phase boundary were fabricated on Pt (111)/ Ti / SiO 2/ Si (100) using the triol sol–gel method. The effect of the pre-heating temperature on the phase transformations, microstructures, electrical properties, and ferroelectric properties of the PZT thin films was investigated. Randomly oriented PZT thin films pre-heated at 400°C for 10 min and annealed at 600°C for 30 min showed well-defined ferroelectric hysteresis loops with a remnant polarization of 26.57 μC/cm2 and a coercive field of 115.42 kV/cm. The dielectric constant and dielectric loss of the PZT films were 621 and 0.0395, respectively. The microstructures of the thin films are dense, crack-free, and homogeneous with fine grains about 15–20 nm in size.

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.

Pzt Thin Films on a Lead Titanate Interlayer Prepared by rf Magnetron Sputering

1993 ◽  
Vol 310 ◽  
Author(s):  
P. H. Ansari ◽  
A. Safari
Keyword(s):  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Lead Titanate ◽  
Silicon Oxide ◽  
Perovskite Phase ◽  
Dissipation Factor ◽  
Lead Zirconate ◽  
Si Substrate ◽  
Pzt Thin Films ◽  
Pzt Films

AbstractFerroelectric lead zirconate titanate (PZT) films with a composition near the morphotropic phase boundary have been deposited by if magnetron sputtering on a Si substrate coated with silicon oxide, titanium, and platinum (Si/SiO2/Ti/Pt). Substrate temperature and oxygen partial pressure were changed during deposition to prepare films with controlled stoichiometry and perovskite structure. The effects of lead titanate (PT) as a buffer layer were investigated. Thin films of PT/PZT have a dielectric constant of 800 with a dissipation factor of 0.04 at 1 kHz. The remnant polarization of 8μC/cm2 and the coercive field of 50 kV/cm were measured. The effect of processing on the formation of perovskite phase and the electrical properties will be discussed.

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.

Preparation of pzt thin films on Pt/Ti/SiO2 and Pt/SiO2 Substrates by ECR Plasma Enhanced DC Magnetron Multi-target Reactive Sputtering

1996 ◽  
Vol 441 ◽  
Author(s):  
Sung-Tae Kim ◽  
Hyun-Ho Kim ◽  
Moon-Yong Lee ◽  
Won-Jong Lee
Keyword(s):  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Electron Cyclotron Resonance ◽  
Perovskite Phase ◽  
Early Stage ◽  
Reactive Sputtering ◽  
Deposition Process ◽  
Pzt Thin Films ◽  
Si Substrates ◽  
Ecr Plasma

AbstractPerovskite-phase lead zirconate titanate (PZT) thin films were fabricated at 4751C by the electron cyclotron resonance (ECR) plasma enhanced DC magnetron multi-target reactive sputtering method on Pt/Ti/SiO2/Si and Pt/SiO2/Si substrates. Stoichiometric perovskite PZT films were readily obtained on Pt/Ti/SiO2/Si substrates because Ti atoms which were out-diffused to the Pt surface facilitated Pb incorporation by forming lead titanate at the early stage of deposition process. Activation of oxygen by ECR plasma facilitated the oxidation reaction and Pb incorporation into the film. Thus perovskite-phase PZT can be obtained on the Pt/SiO2/Si substrate.

Preparation of PbZrxTi1−xO3 Thin Films by KrF Excimer Laser Ablation Technique

1996 ◽  
Vol 433 ◽  
Author(s):  
Hiromitsu Kurogi ◽  
Yukihiko Yamagata ◽  
Tomoaki Ikegami ◽  
Kenji Ebihara ◽  
Bok Yin Tong
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Excimer Laser ◽  
Oxygen Pressure ◽  
Ferroelectric Properties ◽  
Pzt Thin Films ◽  
Excimer Laser Ablation ◽  
Pzt Films ◽  
Krf Excimer Laser ◽  
Laser Ablation Technique

AbstractPb(ZrxTi1−x)O3(PZT) thin films have excellent ferroelectric, optical, piezoelectric and pyroelectric properties. We prepared PZT thin films using the excimer laser ablation technique. A pulsed KrF excimer laser was used to ablate PZT bulk targets. We have studied optimum preparation conditions such as an oxygen pressure, a laser energy fluence and a substrate temperature.In this paper, we investigated the composition, crystallization and ferroelectric properties of the PZT films prepared under various deposition conditions.The X-ray diffraction (XRD) patterns showed that the PZT films prepared on MgO(100) substrates at 600°C and with a laser fluence of 2J/cm2 had a perovskite - pyrochlore mixed structure. The condition of 100 mTorr oxygen pressure provided high quality perovskite films. It is found that the stoichiometric composition of the deposited films is obtained in ambient oxygen of 100˜400 mTorr. The ferroelectric properties of the Pt/PZT/Pt/MgO structure were studied. The capacitance-voltage characteristics and the corresponding hysteresis loop of the dielectric-electric field curve were discussed.We also studied optical emission of the PZT plasma plume to understand quantitative relation between the PZT film quality and the ablation plume plasma. We identified spectral lines originated in Pb, Pb+, Zr, Zr+, Ti, Ti+, PbO and TiO. These spectral intensities have remarkable dependence on the ambient O2 pressure.

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 Local Fatigue Evaluation in PZT Thin Films with Nanoparticles by Piezoresponse Force Microscopy

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
B. S. Li
Keyword(s):  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Precursor Solution ◽  
Grain Morphology ◽  
Piezoresponse Force Microscopy ◽  
Lead Zirconate ◽  
Fatigue Performance ◽  
Pzt Thin Films

Lead zirconate titanate (PZT) thin films with the morphotropic phase boundary composition (Zr/Ti = 52/48) have been prepared using a modified diol-based sol-gel route by introducing 1–5 mol% barium titanate (BT) nanoseeds into the precursor solution on platinized silicon substrates (Pt/Ti/SiO2/Si). Macroscopic electric properties of PZT film with nanoparticle showed a significant improvement of ferroelectric properties. This work aims at the systematic study of the local switching polarization behavior during fatigue in PZT films with and without nanoparticles by using very recent developed scanning piezoelectric microscopy (SPM). We show that the local fatigue performance, which is characterized by variations of local piezoloop with electric cycles, is significantly improved by adding some nanoseeds. It has been verified by scanning electron microscope (SEM) that the film grain morphology changes from columnar to granular structure with the addition of the nanoseeds. On the other hand, the existence of PtxPb transition phase, which existed in interface at early crystallization stage of pure PZT thin film, deteriorates the property of the interface. These microstructures and the interfaces of these films significantly affect the electrons injection occurred on the interfaces. The domain wall pinning induced by injected electrons and the succeeding penetration into the films is discussed to explain the fatigue performance.

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