Liquid-delivery Metalorganic Chemical Vapor Research Articles

Improvement of electrochemical properties in LiCoO2 cathode films grown on Pt∕TiO2∕SiO2∕Si substrates by liquid-delivery metalorganic chemical vapor deposition

The structural and electrochemical properties of LiCoO2 cathode films grown on Pt∕TiO2∕SiO2∕Si substrates at 500°C by liquid-delivery metalorganic chemical vapor deposition (LDMOCVD) were investigated as a function of Li∕Co mol ratio. The electrochemical properties such as initial discharge capacity and cyclic retention were improved through the study of Raman spectra of as-grown and annealed LiCoO2 films. The deposition temperature of 500°C was chosen to characterize the films because films grown at 500°C showed a typical high temperature hexagonal phase without Co3O4 impurities in the films. The optimum annealing condition of as-grown samples with Li∕Co=2.0 and 3.0 was at 700°C for 30min in an oxygen ambient. The highest initial discharge capacity and capacity retention were obtained in Li‖LiCoO2 cells grown with Li∕Co=3.0 and 2.0, respectively, and were approximately 38μAhcm−2μm and 77%, respectively. The compositional window for an optimum electrochemical property exists in the range of Li∕Co=2.0to3.0 in an as-grown temperature of 500°C and annealing temperature of 700°C for 30min in O2.

Preparation and Characterization of RuOx Thin Films by Liquid Delivery Metalorganic Chemical Vapor Deposition

RuOx films were deposited by liquid delivery metalorganic chemical vapor deposition method using a new Ru(C8H13O2)3 precursor for the advanced capacitor electrode in Gbit-scale dynamic random access memory. Deposition was carried out on a TiN barrier layer in the range of 250–400°C and the ratio of the O2 flow rate to the total flow rate of Ar and O2 was varied from 20 to 80%. RuOx thin films were annealed at 650°C for 1 min with Ar, N2 or NH3 ambient. Film characterization was performed in terms of resistivity, crystal structure, surface morphology, microstructure and film purity. The resistivity depended on the impurity, grain density and crystalline structure of the film. The oxygen used to form Ru the oxide was found to eliminate the carbon and hydrogen elements in an organic source. The O2 flow ratio that changes the crystal structure of the films from Ru to RuO2 was found to be 40%. The metallic Ru phase forming a RuO2/Ru bilayer at the RuO2/TiN interface was observed at O2 flow ratios of 50% and 60%. The X-ray diffraction results indicate that the RuO2 phase and the silicidation are not observed regardless of the ambient gases. Ar was more effective than N2 and NH3 as an ambient gas for the postannealing of the Ru films.

Formation of PZT Thin Films on 6-Inch Wafers by Liquid Delivery Metalorganic Chemical Vapor Deposition

Formation of PZT Thin Films on 6-Inch Wafers by Liquid Delivery Metalorganic Chemical Vapor Deposition

Improvement in Structural and Electrical Properties of (Ba0.5Sr0.5)TiO3 Capacitors Using (Ba0.5Sr0.5)RuO3 Conductive Layers at (Ba0.5Sr0.5)TiO3/Pt Interface

BST thin films and BSR interlayers were deposited by pulsed laser deposition (PLD) and liquid-delivery metalorganic chemical vapor deposition (LDMOCVD) onto Pt/TiO2/Si substrates, respectively. Ultrathin BSR conductive layers were inserted at the BST/Pt interface to improve the dielectric properties of BST thin films. BST films deposited on ultrathin BSR interlayers showed an improvement in roughness and microstructure compared with those without BSR layers in an overall range of BST film thickness. The temperature-independent interface capacities in BST/Pt and BST/BSR/Pt structures are approximately 8.9 and 20 µF/cm2, respectively. The dielectric properties of BST films were improved by the increase in interface capacity as well as roughness and microstructure using the BSR conductive layer which is similar to BST in crystal structure and chemical composition.

X-ray diffraction residual stress calculation on textured La2/3Sr1/3MnO3 thin film

Residual stresses and texture in La2/3Sr1/3MnO3 (LSMO) thin films have been investigated. The films were deposited on (100) LaAlO3 (LAO) and (100) MgO single crystals by liquid delivery-metal organic chemical vapor deposition (LD-MOCVD). X-ray diffraction (XRD) pole figures showed (001)LSMO//(001)LAO and (001)LSMO//(001)MgO preferred orientation. Residual stresses were calculated using a modified sin2ψ method, crystallite group method (CGM), assuming a biaxial stress state. Compressive stresses on the order of 224 and 1150MPa were obtained for LSMO films deposited on LAO (LSMO/LAO) and MgO (LSMO/MgO), respectively.

Preparation of Pb(ZrxTi1 - x)O3 Films on Trench Structure for High-Density Ferroelectric Random Access Memory

The growth characteristics of Pb(ZrxTi1 - x)O3 thin films on three-dimensional (3D) electrodes were investigated for the application to high-density ferroelectric random access memory (FeRAM) devices. PZT films have been grown on Ir coated trench structures having aspect ratio of 1.2 by liquid delivery-metal organic chemical vapor deposition (LD-MOCVD). Atomic layer deposited (ALD) Ir electrode showed good step coverage and electrical properties. MOCVD PZT films showed step coverage of 90% at the deposition temperature of 500°C, while it is decreased to 63% at 550°C. Compositional non-uniformity of PZT along the sidewall was greatly affected by the types of the metal organic sources.

Preparation of Strontium Bismuth Tantalate Thin Film by Liquid-Delivery Metalorganic Chemical Vapor Deposition

ABSTRACTThin films of BiOX, SrXTaYO, and SrXBiYTaZO (SBT) were deposited by liquid-delivery metalorganic chemical vapor deposition (MOCVD). The substrate temperature and the deposition pressure were varied from 300 to 600°C and from 0.35 to 7 mbar, respectively. Triallylbismuth (Bi-1), triphenylbismuth (Bi-2) or alkyl bismuth (Bi-3) and strontium bis-pentaethoxy-methoxyethoxy tantalate (Sr-Ta) were used as Bi precursors and as Sr-Ta precursor, respectively. X-ray photoelectron spectroscopy (XPS), ellipsometry, and scanning electron microscopy (SEM) were carried out to characterize the film properties.The growth rates of the MOCVD of BiOX and SrXTaYO were compared to the growth rate of SBT to obtain information about mutual interaction between the precursors. The growth rate of bismuth oxide thin films deposited from Bi-1 and Bi-2 was low (∼10 nm/h at 0.35 mbar). The growth rate of strontium tantalate films was higher (up to 50 nm/h) and depended strongly on the temperature. Eight times higher (∼400 nm/h) growth rates of BiOX and SBT films were observed for the Bi-3 precursor. The deposition rate of the SBT films was quite similar to the rate of the bismuth oxide. However, the deposition rate of SBT was always lower than the deposition rate of the single Bi precursors. The growth rate significantly depended on the deposition pressure. A decrease of the deposition pressure in the reactor chamber reduced the deposition rate of BiOX, SrXTaYO, and SBT, but on the other hand, it improved the uniformity of the film thickness over the entire 150 mm wafer surface.The XPS measurements showed a deficit of bismuth in the SBT films even though the concentration of the Bi-1 or Bi-2 precursor was several times higher compared to the Sr-Ta precursor. This problem disappeared when Bi-3 source was used.

Semiconducting and ferromagnetic properties of Ti[sub 1−x]Co[sub x]O[sub 2] thin films grown by liquid-delivery metalorganic chemical vapor deposition

We have used liquid-delivery metalorganic chemical vapor deposition to grow polycrystalline Ti1−xCoxO2 anatase films with various Co concentrations onto SiO2/Si(100), and have measured the elemental distribution, magnetic properties, and chemical bonding states of the resulting films. The ionic states of Co in ferromagnetic Ti1−xCoxO2 films have the +2 formal oxidation states. Co-rich clusters on the Ti1−xCoxO2 film surface were formed above the limit of solubility of approximately x=0.05. Co-rich clusters formed in Ti1−xCoxO2 films decreased the value of Hc (coercive field) and increased the value of Ms (saturation magnetic field). The Ms and Hc of Ti0.97Co0.03O2 thin films were approximately 20 emu/cm2 and 250 Oe, respectively. The Curie temperature (Tc) of Ti0.97Co0.03O2 thin films is estimated to be higher than 300 K.

Microstructure and Magnetic Properties of Ti1-xCoxO2 Diluted Magnetic Semiconductor Thin Films with Various Co Concentrations by Metal Organic Chemical Vapor Deposition

Polycrystalline <TEX>$Ti_{l-x}$</TEX> <TEX>$Co_{x}$</TEX> <TEX>$O_2$</TEX>thin films on <TEX>$SiO_2$</TEX> (200 nm)/Si (100) substrates were prepared using liquid-delivery metalorganic chemical vapor deposition. Microstructures and ferromagnetic properties were investigated as a function of doped Co concentration. Ferromagnetic behaviors of polycrystalline films were observed at room temperature, and the magnetic and structural properties strongly depended on the Co distribution, which varied widely with doped Co concentration. The annealed <TEX>$Ti_{l-x}$</TEX> <TEX>$Co_{x}$</TEX> <TEX>$O_2$</TEX>thin films with <TEX>$x\leq$</TEX>0.05 showed a homogeneous structure without any clusters, and pure ferromagnetic properties of thin films are only attributed to the X<TEX>$l-x_{l-x}$</TEX> <TEX>$Co_{x}$</TEX>X<TEX>$O_2$</TEX>phases. On the other hand, in case of thin films above x = 0.05, Co-rich clusters formed in a homogeneous <TEX>$Ti_{l-x}$</TEX> <TEX>$Co_{x}$</TEX> <TEX>$O_2$</TEX>phase, and the overall ferromagnetic (FM) properties depended on both FMTCO and FMCo. Co-rich clusters with about 10-150 nm size decreased the value of Mr (the remanent magnetization) and increased the saturation magnetic field.

Structural and electrical properties of LiCoO2 thin-film cathodes deposited on planar and trench structures by liquid-delivery metalorganic chemical vapour deposition

Abstract The electrochemical properties of annealed-LiCoO 2 cathodes deposited on planar and trench structures by liquid-delivery metalorganic chemical vapor deposition are investigated for various deposition temperatures and input Li:Co mole ratios. With the planar structure, the best crystallinity of the films is obtained at a deposition temperature of 450 °C and an input Li:Co mole ratio of 1.0. The deposition window for optimum initial discharge capacity and capacity retention is a deposition temperature of 450–500 °C and an input Li:Co mole ratio of 1.0, and an input Li:Co mole ratio of 1.0–1.2 at a deposition temperature of 450 °C. The initial discharge capacity and capacity retention of LiCoO 2 thin films deposited with an input Li:Co mole ratio of 1.2 at 450 °C are approximately 25 μAh/cm 2 μm and 77%, respectively. The initial discharge capacity of films deposited on a trench structure shows an increase of approximately 130% compared with that of films deposited on a planar structure with an input Li:Co mole ratio of 1.2. The rechargeabilities of films deposited in a trench structure are inferior to those in a planar structure because conformal growth in the trench structure is poor. Thus, a trench structure can improve the initial discharge capacity and capacity retention of lithium microbatteries.

Improvement of discharge capacity of LiCoO2 thin-film cathodes deposited in trench structure by liquid-delivery metalorganic chemical vapor deposition

Pt collector and LiCoO2 cathode films were deposited onto trench-SiO2/Si substrates by liquid-delivery metalorganic chemical vapor deposition (LDMOCVD). The 100-nm-thick Pt thin films deposited at 350 °C showed the lowest resistivity and roughness and step-coverage of 57% in trench structure (aspect ratio-1). The LiCoO2 cathode films (step-coverage=51%) deposited onto a Pt collector showed an increase of approximately two and half times the discharge capacity compared with those of planar-cathode films. The LDMOCVD process is suitable to improve the discharge capacity of LiCoO2 cathode films using a trench structure in lithium rechargeable batteries.

Effects of Co-doping level on the microstructural and ferromagnetic properties of liquid-delivery metalorganic-chemical-vapor-deposited Ti1−xCoxO2 thin films

Polycrystalline Ti1−xCoxO2 thin films on SiO2 (200 nm)/Si (100) substrates were prepared using liquid-delivery metalorganic chemical vapor deposition, and the microstructure and ferromagnetic properties were investigated as a function of doped Co concentration. Ferromagnetic behaviors of polycrystalline films were observed at room temperature, and the magnetic and structural properties strongly depended on the Co distribution, which varied widely with doped Co concentration. The annealed Ti1−xCoxO2 thin films with x⩽0.05 showed a homogeneous structure without any clusters, and pure ferromagnetic properties of thin films are only attributed to the Ti1−xCoxO2 (TCO) phases. On the other hand, in case of thin films above x=0.05, Co1−xTix clusters having a soft magnetic (SM) property formed in a homogeneous Ti1−xCoxO2 phase, and the overall ferromagnetic (FM) properties depended on both FMTCO and SMCo–Ti. Co1−xTix clusters with about 150 nm size decreased the value of Hc (coercive field) and increased the saturation magnetic field.

Ferroelectric properties of SrBi 2Ta 2O 9 thin films with Bi 2O 3 buffer layer by liquid-delivery metalorganic chemical vapor deposition

Ferroelectric SrBi 2Ta 2O 9 thin films were deposited on the Bi 2O 3 buffered Pt/Ti/SiO 2/Si substrates using liquid-delivery metalorganic chemical vapor deposition. The SBT films with a 5-nm-thick Bi 2O 3 buffer layer were well crystallized at a deposition temperature of 540 °C, and with increasing annealing temperature, the SBT thin films showed stronger (115) orientation than those without Bi 2O 3 buffer layer. The value of the remanent polarization of SBT films with Bi 2O 3 buffer layer were improved significantly in comparison with those for films without a Bi 2O 3 buffer layer. The remanent polarization (2 P r ) and coercive field ( E c ) of SBT films without and with a Bi 2O 3 buffer layer annealed at 750 °C were 11.9 and 20.8 μC/cm 2, and 57 and 37.8 kV/cm at an applied voltage of 5 V, respectively.

Fabrication and Characterization of Ru Thin Films Prepared by Liquid Delivery Metal-Organic Chemical Vapor Deposition

Ruthenium thin film was obtained by the liquid delivery metal organic chemical vapor deposition method using a new Ru(C8H13O2)3 precursor for the advanced capacitor electrode in Gbit-scale dynamic random access memory. Deposition was done on a TiN barrier layer in the range of 250–400°C. The thin film characterization was performed in terms of the resistivity, change of crystal structure, surface morphology, microstructure and film purity. The resistivity depended on the impurity, grain shape and crystalline structure of the film. The minimum resistivity of 13.9 µΩ·cm was obtained at 400°C. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that the RuO2 phase and the silicidation are not observed and are independent of the deposition temperature. The carbon and hydrogen contaminants in the Ru film were shown to disturb the crystal preferred orientation growth. The Ru film was found to grow perpendicular to the substrate and to be the columnar structure.

(Ba,Sr)RuO 3 Bottom Electrode Deposited by Liqud Delivery Metalorganic Chemical Vapor Deposition for (Ba,Sr)TiO 3 High Dielectric

Conducting perovskite oxide, (Ba,Sr)RuO 3 (BSR), which has many advantages for (Ba,Sr)TiO 3 (BST) due to their similarity in crystal structure, lattice constant and chemical composition, was prepared on n-type Si (100) by liquid delivery metalorganic chemical vapor deposition (LDMOCVD). The deposition characteristics of BSR were controlled by gas-phase masstransfer in these experiments. The BSR films deposited at 500°C and oxygen flow rate of 100 sccm (standard cc/min) showed a average roughness of 22 Å and resistivity of 810 w z -cm. The resistivity of BSR films for variation of oxygen flow rate showed a close relationship with the roughness of films.

Fabrication of Ferroelectric Pb(Zr,Ti)O3 Thin Films by Liquid Delivery Metalorganic Chemical Vapor Deposition

Pb(Zr,Ti)O3 (PZT) thin films were deposited at the substrate temperature of 550°C by liquid delivery metalorganic chemical vapor deposition (MOCVD). A novel Zr precursor, Zr-isobutyry-pivolylmethane [Zr(DIBM)4]/(Tetrahydrofuran [THF]), was used as a Zr source, and Pb-bis-dipivaloylmethane [Pb(DPM)2]/THF and Ti(OiPr)2(DPM)2/THF were used as Pb and Ti sources, respectively. The Zr content of the deposited films was controlled by changing the supply rate of the Zr source. The molar ratio Zr/(Zr+Ti) of the films was 0.35 when the molar supply rates of Ti and Zr sources were set at 51 and 50 µmol/min, respectively. The properties of the films were changed by changing the supply rate of the Pb source slightly. The PZT films deposited at the Pb supply rate of 56 µmol/min exhibited good shape hysteresis loop shape. The 2Pr and 2Ec of the films with a thickness of 480 nm were 70 µC/cm2 and 125 kV/cm, respectively. The deposition rate was approximately 12 nm/min.

(Ba,Sr)RuO 3 Bottom Electrode Deposited by Liqud Delivery Metalorganic Chemical Vapor Deposition for (Ba,Sr)TiO 3 High Dielectric

Conducting perovskite oxide, (Ba,Sr)RuO 3 (BSR), which has many advantages for (Ba,Sr)TiO 3 (BST) due to their similarity in crystal structure, lattice constant and chemical composition, was prepared on n-type Si (100) by liquid delivery metalorganic chemical vapor deposition (LDMOCVD). The deposition characteristics of BSR were controlled by gas-phase masstransfer in these experiments. The BSR films deposited at 500°C and oxygen flow rate of 100 sccm (standard cc/min) showed a average roughness of 22 Å and resistivity of 810 w z -cm. The resistivity of BSR films for variation of oxygen flow rate showed a close relationship with the roughness of films.

Imprint Characteristics Of SrBi 2 Ta 2 O 9 Thin Films Deposited by Liquid-Delivery Metal Organic Chemical Vapor Deposition

Ferroelectric SrBi 2 Ta 2 O 9 thin films were deposited on 5nm thick-Bi 2 O 3 buffered Pt/Ti/SiO 2 /Si substrates using liquid-delivery metalorganic chemical vapor deposition. Imprint characteristics have been observed by dynamic imprint measurement after exposing the film capacitors to unipolar pulses at 125°C. The voltage shift changes with cumulative total time at maximum voltage. The origin of the voltage shift is briefly discussed in terms of an internal bias voltage induced by injected electrons trapped at positive polarity. The charge shift was due to the internal bias voltage formed by imprint test, and the magnitude of change shift of SBT thin films without a Bi 2 O 3 buffer layer was larger than that of SBT thin films with a Bi 2 O 3 buffer layer.

The Role of Bi 2 O 3 Interfacial Layer in Improvement of Ferroelectric Properties of SrBi 2 Ta 2 O 9 Thin Films Deposited by Liquid-Delivery MOCVD

Ferroelectric SrBi 2 Ta 2 O 9 thin films were deposited onto the Bi 2 O 3 /Pt/Ti/SiO 2 /Si substrates using liquid-delivery metalorganic chemical vapor deposition technique (liquid delivery MOCVD). The SBT thin films deposited on Pt/Ti/SiO 2 /Si substrate at 540 were not crystallized, however, the SBT films with Bi 2 O 3 interfacial layer were well crystallized at deposition temperature of 540 , and with increasing annealing temperature, the SBT thin films showed stronger (115) orientation than those without Bi 2 O 3 interfacial layer. The value of the remanent polarization of SBT films with Bi 2 O 3 interfacial layer were improved significantly in comparison with those for the films without Bi 2 O 3 layer. The remanent polarization (2P r ) and coercive field (E c ) of Pt/SBT/Pt/Ti/SiO 2 /Si and Pt/SBT/Bi 2 O 3 /Pt/Ti/SiO 2 /Si capacitors annealed at 750 were 11.9 and 22.5 C/cm 2 , and 57 and 38 kV/cm at an applied voltage of 5V, respectively.

Structural Stability of (Ba,Sr)RuO 3 Electrodes on Hydrogen Annealing and Effect of interfacial Layers in (Ba,Sr)TiO 3 Thin Films

(Ba,Sr)RuO 3 (BSR) electrodes were deposited on n-type Si (100) substrates by liquid-delivery metalorganic chemical vapor deposition (LDMOCVD) and their stability in a hydrogen ambient was investigated. BSR films showed the structural and morphological stability when annealed in hydrogen forming gas (4 % H 2 +96% balance N 2 ) temperatures of up to 500 . The abrupt increase of resistivity with increasing hydrogen annealing temperature can be attributed to oxygen loss in BSR films without phase change and was completely recovered by annealing at 700 in an O 2 ambient. The dielectric constant of the Pt/BSR/BST/Pt structures increased with increasing BSR interfacial layers. The dielectric constant of a BSR/BST/Pt capacitor with a 35 nm thick BST without top Pt electrode showed about 425.