摘要:

The use of integrated ferroelectric capacitors as nonvolatile memory elements in semiconductor memory designs imposes additional electrical performance requirements on the capacitor which are not normally characterized in ferroelectric materials research. This paper will describe those requirements and present a suggested set of testing procedures we have developed for their standardized measurement. The most significant property for memory design is not the oft quoted traditional Sawyer-Tower continuous remanent polarization, but rather pulsed remanent polarization which can be broken down into transient remanent polarization or depolarization, which decays within one second, and retained polarization, thereafter. Retained polarization is almost always less than continuous remanent polarization. Instead of the traditional coercive voltage, we propose the concept ofthreshold voltage, defined as that voltage required for 1 μC/cm2differential pulsedlong termremanent polarization of capacitors polarized in opposite states. The accurate measurement of pulsed polarization depends on the testing methodology employed. We have developed a rigorous testing procedure to produce consistent measurements in volving pulse widths, pulse risetimes, pulse delays, capacitor sizes, voltage levels, repetition rates, and other details which are presented and discussed.

ISSN:1058-4587    

DOI:10.1080/10584589308216704

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A low thermal budget (with 550°C annealing) process with Ti-compensation for sputtered ferroelectric PZT thin films has been developed. PZT films with a composition near the morphotrophic phase boundary (Zr/Ti = 53/47) annealed at 550°C for 1 hr in a N2ambient exhibits high charge storage density and low leakage current density, which are the important requirements of dielectric materials for ULSI DRAM cells. It was also found that Ti compensated films show good fatigue endurance in comparison with non-Ti compensated films.

ISSN:1058-4587    

DOI:10.1080/10584589308216705

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Suitability of oxide electronic conductors [e.g. ruthenium oxide (RuOx) and indium-tin-oxide (ITO)] as contact metallization for ferroelectric films (e.g. PbZrxTi1−xO3) was investigated using techniques such as Rutherford backscattering spectrometry, x-ray diffraction and electron spectroscopy for chemical analysis. Thin films of RuOxand ITO were deposited on Si substrates by reactive sputtering. Either PbO or PZT (x = 0.53) films were deposited onto the conducting oxides and the specimens were annealed at various temperatures between 400°C and 700°C. Less intermixing was found in Si/RuOx/ PZT films when compared to Si/ITO/PZT under similar processing conditions. The ferroelectric properties of PZT films on RuOxelectrodes are compared to those on Pt electrodes. The PZT films show improved fatigue properties on RuOxelectrodes.

ISSN:1058-4587    

DOI:10.1080/10584589308216706

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Organometallic chemical vapour deposition is a suitable technique for the deposition of thin films of oxidic compounds such as lead zirconate titanate, PbZrxTi1−xO3. Above a deposition temperature of about 600°C stoichiometric PbZrxTi1−xO3films can be grown on platinized silicon wafers within a large process window, independent of the precursor partial pressures and the deposition temperature. This is the result of a self-regulating mechanism. The PbZrxTi1−xO3films have excellent ferroelectric properties exhibiting high values, up to 60μC/cm2, for the remanent polarisation. The value of the coercive field strength varies between 50 and 180 kV/cm, dependent on the composition. Layers with comparable properties can also be grown at lower temperatures, down to 500°C. In this case careful control of the gas-phase composition is required to obtain films with the correct stoichiometry.

ISSN:1058-4587    

DOI:10.1080/10584589308216707

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Pulsed laser ablation has been used to deposit ferroelectric Pb(Zr, Ti)O3(PZT) thin films on Si(100) and on yttrium-treated Si(100) substrates. The yttrium (Y) treatment of a Si surface followed by oxidation resulted in formation of a very thin, Y-enhanced SiO2antidiffusion barrier layer, thereby suppressing the undesirable PZT/Si interdiffusion. The best PZT film grown on Y-treated Si(100) had a breakdown voltage of 0.6 MV/cm, a coercive field of 71 KV/cm, and a remanent polarization of 18 μC/cm2.

ISSN:1058-4587    

DOI:10.1080/10584589308216708

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We have grown high quality La0.5Sr0.5CoO3thin films by Pulsed Laser Deposition. This material is a electrically conducting perovskite which can be used as structurally compatible electrodes for devices using ferroelectric materials such as Pb-La-Zr-Ti-O (PLZT). Oxygen stability was investigated under various annealing conditions. LSCO/PLZT/LSCO heterostructures were grown epitaxially on SrTiO3(STO) and MgO substrates. P-E hysteresis loop was observed with Pr= 20 μC/cm2and Ec= 24 kV/cm. Direct observation of the piezoelectric effect in PLZT was made by measuring the PLZT c-axis lattice constant under various electric fields. LSCO/STO superlattice was also grown by PLD. The superlattice showed excellent crystallinity with a Rutherford Backscattering (RBS) channeling minimum yield of only 3.6%.

ISSN:1058-4587    

DOI:10.1080/10584589308216709

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

System, device and material issues for the use of ferroelectric ceramic thin films in the realization of Smart Spatial Light Modulators are considered. Results show that ferroelectric thin films such as PLZT PBN, KTN, and SBN are particularly attractive.

ISSN:1058-4587    

DOI:10.1080/10584589308216710

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The electrical properties of thin film (<1000 Å) capacitor devices of lithium niobate grown on silicon and platinum and of thicker film metal-ferroelectric-semiconductor field effect transistors (MFSFET) with lithium niobate as the gate material were measured. Dielectric constants of the thin films on silicon were as high as 27, while those for films on platinum were as high as 49. The MFSFET structures showed good FET properties, and demonstrated a channel current modulation consistent with switching of the ferroelectric gate by pulsing.

ISSN:1058-4587    

DOI:10.1080/10584589308216711

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Switched remanent polarization was measured as a function of accumulated switching cycles for a variety of ferroelectric films using sinusoidally driven hysteresis loops. Switched remanent polarization and dielectric constant and loss were also obtained as a function of the cycling frequency. PZT films with niobium additives appeared to lose switched remanent polarization with accumulated cycles at a lesser rate than films without niobium. The switched remanent polarization was found to decrease with increasing frequency, which we attribute to the effect of grain size. Also, a decrease of dielectric constant with increasing frequency and an increase of dielectric constant with increased applied voltage are attributed to the effects of domain wall motion contributions to dielectric constant.

ISSN:1058-4587    

DOI:10.1080/10584589308216712

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor