1,720,962 research outputs found
Intrinsic stress dependence of c-axis orientation ratio in PbTiO3 thin films deposited by reactive sputtering
No full textHighly c-axis oriented lead titanate (PbTiO3) thin film, having a perovskite structure, was prepared on magnesium oxide (MgO) (100) single crystal using multiple cathode dc-magnetron sputtering at 600 degrees C. The film was annealed at 700 degrees C for up to 8 h. Both the c-axis orientation ratio P and c-axis lattice parameter of the film decreased with the increase of the annealing time. It was confirmed that the decrease of the c-axis lattice parameter with the annealing time was due to the relaxation of the intrinsic stress generated during deposition. These experimental results suggested that P was related to the intrinsic stress. The film deposited at various working pressures was examined in detail to confirm the intrinsic stress effect of P. P of 95% at 8 mTorr decreased to 60% at 70 mTorr. The pressure dependence of P was explained by the intrinsic stress change. Regardless of the sputtering condition, all P's were reduced to 40% after annealing at 700 degrees C for 8 h. The difference in P between the before and after annealing was caused by the relaxation of the intrinsic stress. It was supposed that the remaining 40% of P after the heat treatment was caused, in the most part, by the ferroelectric phase transition. (C) 1997 American Vacuum Society
Identification of microstructure reaction products in active filler metal/alumina brazement
No full textPlatinum(100) hillock growth in a Pt/Ti electrode stack for ferroelectric random access memory
No full textThe Pt hillock in a Pt/Ti electrode stack has been the main concern in ferroelectric random access memory due to the reliability problem. The origin of the hillock formation is the compressive stress, and the main mass transport mechanism for hillock formation is the grain boundary diffusion for thin films with a columnar structure. However, the hillock growth orientation and mechanism have not been reported. In this study, we found that an orientation relationship of Pt(100)(hillock)//Pt(111)(thin film) existed between the Pt hillock and the thin film. The Pt hillock was a single crystal having facets with polyatomic steps. From these results, we suggest that the Pt hillock growth mechanism is the layer growth of flat faces, which shapes the hillock into a tetrahedron single crystal. (C) 2003 American Institute of Physics.This work was supported by Grant No. R01-2000-00226 from the basic research program of the Korea Science and Engineering Foundation. It was also supported by the Brain Korea 21 project in 2003 and the Ministry of Science and Technology (M1010500066-01H2006400)
Surface characterization of diamond films polished by thermomechanical polishing method
No full textThe rough grown surface of a diamond film deposited by the hot filament chemical vapour deposition (CVD) method was polished by thermomechanical polishing on a hot iron plate at 1173 K. The surface composition and structure of the polished diamond film were analysed by Raman spectroscopy, Auger electron spectroscopy (AES), thin film X-ray diffraction (XRD) and secondary ion mass spectrometry (SIMS). The graphitization of the near-surface region of the diamond film by the hot iron plate was observed during thermomechanical polishing. At the diamond film/Si interface, beta-SiC was observed during the early stages of polishing, but after prolonged treatment the graphitization of the diamond film occurred rapidly
Platinum hillocks in Pt/Ti film stacks deposited on thermally oxidized Si substrate
No full textThe stress dependence of platinum hillock formation during post thermal cycling was investigated in Pt/Ti electrode stacks. Annealing temperatures were varied from room temperature (RT) to 650 degreesC. High compressive stress was generated during electrode annealing by the Ti diffusion into the platinum layer followed by oxidation in the platinum grain boundaries. The compressive stress was the major driving force for the hillock formation on the platinum surface, Thus. the Ti glue layer was oxidized before platinum deposition to reduce the Ti diffusion. The Pt/TiOx electrode stack retained its smooth platinum surface after the electrode annealing of 650 degreesC for 30 min in O-2. The Pt/TiOx interface remained flat even after the ferroelectric annealing at 800 degreesC, which was performed after SrBi2Ta2O9, (SBT) deposition. Moreover, the remanent polarization (2P(r),) of the SBT capacitor was increased to 17 muC/cm(2) on the Pt/TiOx electrode stack, up from 13 muC/cm(2), which was the value on the Pt/Ti electrode stack
Platinum (100) hillock growth in Pt/Ti electrode stack for SrBi2Ta2O3 ferroelectric random access memory
No full textPlatinum (100) hillock growth in Pt/Ti electrode stack for SrBi2Ta2O9 ferroelectric random access memory
No full textThe ferroelectric material SrBi2Ta2O9 (SBT) has been extensively investigated in connection with integrating nonvolatile ferroelectric random-access memory (FeRAM). The SBT layer must be annealed in an oxygen atmosphere after deposition to crystallize the ferroelectric oxide film, which induces Pt hillock formation in a Pt/Ti electrode stack. The Pt hillock in a Pt/Ti electrode stack has been the main concern in SBT FeRAM due to reliability problems, such as capacitor shorts. Reportedly, the compressive stress generated in thin film is widely accepted as being responsible for the occurrence of hillocks in thin film and the main mass transport mechanism for hillock formation is the grain boundary diffusion for thin film with a columnar structure. In this study, three factors are considered in the total compressive stress generated during both deposition and post-annealing in Pt/Ti electrode stack: intrinsic stress, thermal stress, and extrinsic stress. Moreover, we found that an orientation relationship of Pt (100)(hillock)//Pt (111)(thin film) existed between the Pt hillock and the thin film. The Pt hillock was a single crystal, having facets with polyatomic steps. From these results, we suggest that the Pt hillock growth mechanism is the layer growth of flat faces, which shapes the hillock into a tetrahedron single crystal.This work was supported by grant no. R01-2000-00226 from the basic research program of the Korea Science & Engineering Foundation. It was also supported by the Brain Korea 21 project in 2003 and the Ministry of Science and Technology (M1010500066-01H2006400)
Stacked Pt/SrBi2Ta2-xNbxO9/Pt/IrOx/Ir capacitor on poly plug
No full textA Pt/SrBi2Ta2-xNbxO9(SBTN)/Pt/IrOx/Ir capacitor was successfully fabricated up to the stage of metal-1 etching process on a polysilicon plug for mega-bit ferroelectric random access memory. The integration processes include the chemical-mechanical polishing technique, buried TiN barrier structure and electrode technologies for high thermal stability, and a low-temperature process for SBTN film. The thickness of the iridium layer was the most important factor in controlling the contact resistance of the plug. The Pt thickness also affected the contact resistance of the plug. The best contact resistance of the plug was about 2.0 kOhm/plug at the maximum process temperature of 750degreesC for 3 min in oxygen ambient at the contact site of phi0.30 mum. Hysteresis curves of the SBTN capacitor were obtained after the metal-1 etching process. The capacitor size dependency of the polarization was not observed in the range of 0.30-25 mum(2) and the values of the sensing polarization were about 10 muC/cm(2) at the applied voltage of 3 V. In addition, the capacitor exhibited no fatigue loss up to 5 x 1010 cycles at the,witching voltage of 3 V
Thermal stability and electrical properties of SrBi2Ta2-xNbxO9/IrOx capacitors with Pt top electrode
No full textBoth SrBi2Ta2-xNbxO9 (SBTN) film and IrOx electrode were used for fabricating a capacitor of high-density ferroelectric random access memory. IrOx was deposited by reactive sputtering, and the spin-on technique was used for coating the SBTN layer. Marked evaporation was observed in 2000-Angstrom -thick IrOx film after electrode annealing at temperatures above 700 degreesC. The evaporation was caused by the reduction of IrOx to metallic iridium. However, SBTN/IrOx stack remained stable even after annealing up to 800 degreesC. Ferroelectric crystallization annealing during the integration was performed at 650 degreesC for the application of stacked capacitor architecture. Thus, the Pt/SBTN/IrOx capacitor could be fabricated up to metallization without damaging the microstructure, The switching polarization was about 10 muC/cm(2) at the 2.4 mum x 3.7 mum x 256 ea array capacitor after metallization and the leakage current density was about 4 x 10(-7) A/cm(2) The contact resistance of the SBTN/IrOx/Ir/TiN/plug was about 1500 Omega /plug at the contact size of phi 0.30 mum
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