Polar ceramics in rf-MEMS and microwave reconfigurable electronics: A brief review on recent issues

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In small area capacitive reactors, the rf and dc components of the plasma potential can be assumed to be uniform over all the plasma bulk because of the low plasma resistivity. In large area reactors, however, the rf plasma potential can vary over a long range across the reactor due to rf current flow and the nonzero plasma impedance. A perturbation in rf plasma potential, due to electrode edge asymmetry or the boundary of a dielectric substrate, propagates along the resistive plasma between capacitive shea

This work dealt with the establishment of a reproducible and industrially exploitable fabrication technology for piezoelectric MEMS based on PZT thin films. {100}-textured piezoelectric 1-4 μm thick films were found to be the most suited materials for MEMS applications where a strong transverse e31,f coefficient is required. Values of 11.5 to 12.5 C/m2 throughout the investigated thickness range have been obtained. PZT MEMS requires some special microfabrication processes. The patterning of platinum electro

The direct observation of blocked polarization domains at the electrode-ferroelectric interface of electrically fatigued ferroelectric films is reported. Blocked nanodomains are believed to be the origin of polarization fatigue in ferroelectric nonvolatile memories but have not been directly observed so far due to the required upper metal electrode which impedes the direct access to the surface of the ferroelectric film. This problem has been solved by using low temperature melting metal as removable top el

Thin films of neodymium-modified bismuth titanate Bi3.44Nd0.56Ti3O12 (BNT) were grown on Pt/TiO2/SiO2/Si substrates using chemical solution deposition method. The capacitors made by applying top Au electrodes on BNT films showed significantly improved values of the remanent polarization as compared to that using bismuth titanate Bi4Ti3O12 (BT) films. The 2P(r) value for the BNT capacitors was determined to be equal to 38 muC/cm(2) at an applied voltage of 24 V, whereas, for Bi4Ti3O12 ( BT) capacitors a valu

Fabrication of high-density ferroelectric memories requires the growth of the ferroelectric material on the drain contact metal. In standard 0.5 mum technology, tungsten plugs are applied to connect the drain contacts to the first metallization level. In this work, we investigated electrode systems to be applied between sputter deposited, ferroelectric PbZr0.35Ti0.65O3 (PZT) and tungsten. Besides the obvious barrier function of such an electrode system, the texture of the PZT is of interest as well. The rou

Polymeric precursor solution (Pechini method) was used to deposit LiNbO3 thin films by spin-coating on (100) silicon substrates. X-ray diffraction data of thin films showed that the increase of oxygen flow promotes a preferred orientation of (001) LiNbO3 planes parallel to the substrate surface. Surface roughness and grain size, observed by atomic force microscopy, change also with oxygen flow.

The incorporation of up to 40 % lead excess into the perovskite lattice of Pb(Zr,Ti)O-3 (PZT) has been investigated. Three independent chemical composition analysis methods confirmed the correct determination of the lead excess, present as Pb2O3. High resolution TEM excludes any second phases and restricts the occurrence of lead excess to the perovskite lattice, suggesting a lead oxide perovskite of the form Pb2+Pb4+O3 with a 4-valent ion on the B-site. PZT containing such lead excess is thus a solid soluti

A unified approach for analysis of polarization fatigue and size effects on ferroelectric switching in relationship with injection and entrapment of charge at the interfacial layer of the ferroelectric film is developed. The proposed model suggests that an enhancement of the entrapped charge relaxation at the interfaces has a positive impact on both the polarization fatigue and size effects. This concept is implemented experimentally by introducing a thin conductive oxide (RuO2) layer into the top interface

The structure of the antiphase domain boundaries of strontium titanate SrTiO3 that exist at temperatures below the antiferrodistortive transition, is analyzed. It is found that some boundaries are similar to Neel domain walls, as an additional component of the order parameter develops within them. We show quantitatively that at low temperatures, typically below similar to 40 K, such boundaries become unstable with respect to the development of a ferroelectric polarization. This ferroelectric transition migh

This paper reviews deposition, integration, and device fabrication of PbZrxTi1-xO3 (PZT) films for applications in micro-electromechanical systems. An ultrasonic micromotor is described as an example. A summary of the published data on piezoelectric properties is given. The figures of merit for various applications are discussed. Some considerations and results on operation, reliability, and depolarization of PZT thin films are presented. The state of the art allows some preliminary conclusions.

Pb(Mg1/3Nb2/3)O-3 thin films were prepared from modified alkoxide solution precursors and their dielectric and electromechanical characteristics were investigated. Preparation of the films is very sensitive to processing parameters. The influence of different seeding layers on the microstructures is discussed. Films show relaxer-like behavior, but with dielectric permittivity which is low (4500 at peak) compared to bulk ceramics and single crystals. Large electric de bias fields (up to 120 kV/cm) can be app

The domain nucleation and growth during the switching process in ferroelectric PZT thin film capacitors was observed using atomic force microscope (AFM) technique combined with a lock-in amplifier. The measured phase difference between the tip vibration signal induced by the piezoelectric displacement and the low ac modulation voltage applied to the ferroelectric capacitor was used to determine the domain polarity whereas the tip vibration amplitude was used to determine the piezoelectric coefficient. As de

Polar ceramics in rf-MEMS and microwave reconfigurable electronics: A brief review on recent issues

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Nonuniform radio-frequency plasma potential due to edge asymmetry in large-area radio-frequency reactors

Piezoelectric acoustic sensors and ultrasonic transducers based on textured PZT thin films

Direct observation of inversely polarized frozen nanodomains in fatigued ferroelectric memory capacitors

Properties of chemical solution deposited polycrystalline neodymium-modified Bi4Ti3O12

Tungsten based electrodes for stacked capacitor ferroelectric memories

Influence of oxygen flow on crystallization and morphology of LiNbO3 thin films

Excess lead in the perovskite lattice of PZT thin films made by in-situ reactive sputtering

Charge relaxation at the interfaces of low-voltage ferroelectric film capacitors: Fatigue endurance and size effects

Prediction of a low-temperature ferroelectric instability in antiphase domain boundaries of strontium titanate

PZT thin films for microsensors and actuators: Where do we stand?

Relaxor Pb(Mg1/3Nb2/3)O-3 thin films and their electromechanical properties

Observation of domain nucleation and growth during switching process