摘要:

As CMOS dimensions shrink so does the limitation on total thermal budget for processing. For 0.18 μm design rules, the junction depth and the salicide process requirements limit the maximum processing temperature to below 700°C, preferably down to 650°C. For FeRAMs, this results in limitation on the thermal budget available for the crystallization of ferroelectric films. SBT and SBTN films have been generally annealed at 700°C or higher. Lowering the crystallization temperature down to 650°C requires the suppression of fluorite phase in order to obtain good ferroelectric performance. We have developed a CSD based low temperature process for SBT films yielding excellent ferroelectric properties. Several materials and process parameters have been optimized to suppress the fluorite phase. These include film stoichiometry and thickness, anneal ambient and ramp rates, UV energy and precursor solvents. In this paper we present a complete 650°C process for SBT thin films, highlighting process modifications and their effect on ferroelectric performance.

ISSN:1058-4587    

DOI:10.1080/10584580008222247

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Thin films of pure and acceptor (Al) as well as donor (Nb) doped PbTiO3were prepared using a chemical solution deposition method. The nominal compositions of the solutions were equivalent to those of PbTiO3, Pb(Ti0.95Al0.95)O3and Pb(Ti0.95Nb0.05)O3, respectively. In the case of PbTiO3, the remanent polarization amounted to 43 μC/cm2, but the shape of the hysteresis curve was round. On the other hand, Al and Nb doped PbTiO3thin films exhibited well-saturatedP-Ehysteresis curves. The shape of these curves was slim compared to that of PbTiO3. The remanent polarization of the Pb(Ti0.95Al0.05)O3and Pb(Ti0.95Al0.05)O3thin films amounted to 18 and 15 μC/cm2, respectively, and the coercive field decreased in comparison with that of PbTiO3. The leakage currents of the PbTiO3, Pb(Ti0.95Al0.05)O3and Pb(Ti0.95Al0.05)O3thin films were 7.68x10−3, 3.21x10−6and 6.58x10−4A/cm2, respectively, at+10V.

ISSN:1058-4587    

DOI:10.1080/10584580008222248

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Liquid Injection Chemical Vapour Deposition is a technique well suited to the deposition of a range of ferroelectric oxides in thin film form. This paper reports on the design and optimisation of the precursors for the deposition of thin films of the promising pyroelectric material, lead scandium tantalate. The design and use of lead, scandium and tantalum precursors with carefully matched chemical and thermal properties allows the growth of thin films with the required perovskite phase above 550°C. These have the desired 111 orientation when grown on to platinum coated silicon substrates at temperatures above 575°C.

ISSN:1058-4587    

DOI:10.1080/10584580008222249

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The ferroelectric SBT films were deposited on Pt/Ti/SiO2/Si substrates by liquid injection metalorganic chemical vapor deposition (MOCVD) with single-mixture solution of Sr[Ta(OEt)5(dmae)]2and Bi(C6H5)3. The Sr/Ta and Bi/Ta ratio in SBT films depended on deposition temperature and mol ratio of precursor in the single-mixture solution. At the substrate temperature of 400°C, Sr/Ta and Bi/Ta ratio were close to 0.4 and 1 at precursor mol ratio of 0.5∼1.0. As-deposited film was amorphous. However, after annealing at 750°C for 30 min in oxygen atmosphere, the diffraction patterns indicated polycrystalline SBT phase. The remanent polarization (Pr) and coercive field (Ec) of SBT film annealed at 750°C were 4.7 μC/cm2and 115.7 kV/cm at an applied voltage of 5 V, respectively. The SBT films annealed at 750°C showed practically no polarization fatigue up to 1010switching cycles.

ISSN:1058-4587    

DOI:10.1080/10584580008222250

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Low temperature metal-organic chemical vapor deposition (MOCVD) processes for producing high dielectric (Ba, Sr)TiO3(BST) films studied using a noble dome type reactor, liquid delivery technique and new precursors. One of the problems associated with conventional MOCVD reactors having a shower head was substrate surface-dependent deposition of film composition as well as the thickness, which might result in pattern-dependent deposition of BST films. The new chamber used in this study was capable of controlling both the substrate heater and chamber wall temperatures which successfully eliminated such surface-dependent deposition property. The film composition and thickness were essentially the same on either Pt and SiO2surfaces when both the wall and heater temperatures were controlled. However, the film composition, thickness and uniformity were differed markedly on the Pt and SiO2surfaces when only the heater temperature was controlled. Excellent step coverage and smooth (haze-free) surface morpholgy of BST films were obtained from a deposition at 470°C.

ISSN:1058-4587    

DOI:10.1080/10584580008222251

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Low temperature metal-organic chemical vapor deposition (MOCVD) process of Ru films for use as electrode material was studied using a noble dome type reactor, liquid delivery technique and a new precursor. The films were grown at temperatures ranging from 275°C to 480°C in which film growth was controlled by a surface chemical reaction with a small activation energy of 0.21 eV. The root-mean-squared surface roughness was as low as 23 Å for a film grown at 290°C on a SiO2surface.

ISSN:1058-4587    

DOI:10.1080/10584580008222252

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

BaTiO3(BTO) and SrTiO3(STO) and BaxSr1-xTiO3(x=0–1) (BST) thin films have been epitaxially grown on LaAlO3and SrTiO3:Nb at a substrate temperature of 800°C using a new liquid source delivery technique called injection MOCVD. A X-ray study evidenced FWHMs of 0.16° and 0.45° for SrTiO3and BaTiO3respectively.

ISSN:1058-4587    

DOI:10.1080/10584580008222253

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Crystallization behavior and ferroelectric properties of the PbTiO3, PT, thin films prepared by spin-coating of nano-powder incorporated carboxylates were systematically examined. Comparing to the direct synthesis of PT films by metal-organic decomposition process, the incorporation of nano-sized PT powders into the carboxylates markedly modifies the crystallization kinetics of the PT films. Pure perovskite phase can be obtained by post-annealing these films at 600°C for 1 h and the remanent polarization for the films can be optimized only by post-annealing at high enough temperature (650°C). However, the nano-powder incorporated PT films possess pronouncedly lower remanent polarization (Pr) and smaller coercive field (Ec) than the non-powdered PT films. Such a phenomenon is ascribed to the formation of multi-grain structure in each column of the films.

ISSN:1058-4587    

DOI:10.1080/10584580008222254

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Metal Organic Chemical Vapour Deposition was used to grow PbTiO3and PbZrxTi1-xO3thin films on Pt/Ti/SiO2/Si substrates. Incorporation of Pb and Ti into PbTiO3was studied as a function of the growth temperature, gas phase composition, and reactor pressure, keeping the other deposition parameters constant. The stoichiometric homogeneity in lateral and in vertical direction was measured on optimised PbTiO3and PbZrxTi1-xO3layers using Inductive Coupled Plasma – Atomic Emission Spectroscopy.

ISSN:1058-4587    

DOI:10.1080/10584580008222255

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Selective modification of zirconium alkoxide by acetic acid or acetylacetone was used in solution processing of PZT Pb(Zr, Ti)O3thin films by 2-methoxyethanol route. EXAFS results clearly show a decrease of Zr-O-Zr links in the acetic acid modified PZT sol implying a more homogeneous constituent metal distribution. No such decrease in comparison to unmodified sol is found in acetylacetone modified PZT. Higher level of homogeneity achieved in modified PZT sols evokes the perovskite crystallization in thin films and decreases the crystallization temperature on (0001) sapphire. On TiO2/Pt/TiO2/Si the modifiers affect the relative orientation of the perovskite phase.

ISSN:1058-4587    

DOI:10.1080/10584580008222256

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor