Search

Sr1 + xNd2Al2O7 + x (0 ≤ x ≤ 0.04) ceramics were prepared using a more concise reaction-sintering method. The reaction-sintering (RS) method could reduce the number of ceramic preparation steps, which in turn reduces the factors that cause degradation of the microwave dielectric properties due to the sophisticated process fluctuations in the sintering process. X-ray diffraction patterns show that the sample is composed of a pure SrNd2Al2O7 single phase, whereas scanning electron microscope images display that the microscopic morphology of the sample is almost the same as that of solid-phase sintering. As x = 0.03, Sr1 + xNd2Al2O7 + x ceramic sintered at 1600 °C exhibited good microwave dielectric performances with εr = 18.53, Q × f = 68,600 GHz, τf = − 3.49 ppm/°C, and ρ = 6.03 g/cm3, which were better than those of the solid-state reaction method, indicating that the RS method has a lower cost and is simpler for preparing microwave dielectric ceramics with good performances. [ABSTRACT FROM AUTHOR]

Crystallization behavior and morphology of PLA blended with 0.05-1.00 wt % loadings of poly(D-lactic acid) (PDLA) forming stereocomplex crystallites as in-situ nucleating agents, were studied using wideangle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and polarizing-light optical microscopy (POM). Blending PLA with small amount of PDLA does lead to formation of PLA stereocomplex (SC), although the PLA is a random copolymer. The in-situ formed SC crystal acted as nucleation sites in blends and accelerated the crystallization of PLA by decreasing the half-time (t1/2). The nucleation efficiency of PDLA obviously increased and the crystallization induction time decreased while the content of PDLA reached up to 0.20 wt %. While the content of PDLA is 0.2 wt %, the nucleation efficiency of PDLA is up to 43.8%, and the induction time decreased from 430 to 88 s. In addition, compared with pure PLA, t1/2 decreases from 15.1 to 3.5 min at Tc = 127.5°C while the amount PDLA is 1.0 wt %. The equilibrium melting temperature of PLA decreased from 187.2 to 181.2°C with the increase of PDLA content. [ABSTRACT FROM AUTHOR]

ABSTRACT Ultrasonics was used to improve the dispersion of NaA zeolite in polyacrylic acid sodium (PAAS) membranes. The effect of ultrasonication time on the dispersion of NaA zeolite in the membranes, the membrane structure, and performance were investigated. The casting solution and resulting membranes were characterized by viscosity measurement, polarizing optical microscopy (POM), scanning electron microscopy, and X-ray diffraction (XRD). With increasing ultrasonication time, the viscosity of the casting solution decreased as the chain entanglements decreased. The POM and XRD results showed that crystallization occurred in the PAAS membrane after ultrasonic processing. A more homogeneous morphology was obtained due to improvement in the dispersion of zeolite under ultrasonic treatment for 0.5-1.0 h. As a result, the separation performance was enhanced. The water/ethanol separation factor increased from 176.2 to 577.8. However, the relative separation factor decreased when the ultrasonic time exceeded 2.5 h, due to the appearance of a lamellar structure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3979-3984, 2013 [ABSTRACT FROM AUTHOR]

Abstract: Ultrathin Vanadium nitride (VN) thin film with thickness around 10nm was studied as diffusion barrier between copper and SiO2 or Si substrate. The VN film was prepared by reactive ion beam sputtering. X-ray diffraction, Auger electron spectroscopy, scanning electron microscopy and current–voltage (I–V) technique were applied to characterize the diffusion barrier properties for VN in Cu/VN/Si and Cu/VN/SiO2 structures. The as-deposited VN film was amorphous and could be thermal stable up to 800°C annealing. Multiple results show that the ultrathin VN film has good diffusion barrier properties for copper. [Copyright &y& Elsevier]

Thermal stability, phase and interface uniformity of Ni-silicide are some key issues for NiSi Salicide technology. The improved stability of NiSi was achieved by Ni/Pt/Si and Ni/Pd/Si reaction. The increase of thermal stability can be explained by classical nucleation theory. The phase and interface uniformity of Ni-silicides formed by Ni–Si solid-state reaction were characterized by X-ray diffraction (XRD) and temperature-dependent current–voltage (I–V–T) techniques. Results show that the Schottky barrier height (SBH) inhomogeneity characteristic has strong dependence on annealing temperature for Ni-silicide formation. Deep level transient spectroscopy (DLTS) measurement shows that annealing at relatively low temperature may cause electrically active deep level defects in the film. These results show that choosing a proper annealing temperature for Ni/Si silicidation will be very important for device performance. [Copyright &y& Elsevier]

Ultrathin sputtered W–Si–N films (~10 nm) were prepared for copper metallization. While copper was sequentially deposited onto some samples without breaking the vacuum, some samples underwent annealing before copper deposition. The precopper deposition annealing (simplified as preannealing) was carried out by rapid thermal annealing (RTA) in high purity N2 atmosphere. Sheet resistance measurement, Auger electron spectroscopy (AES) and X-ray diffraction (XRD) results all show that the preannealing procedure significantly increased the failure temperature for copper/diffusion barrier/Si structure by about 100°C compared with those without preannealing. Bias leakage current versus time (I–t) measurement and bias temperature C–V measurement, which are very sensitive for mobile ions in the oxide, also show that the copper gate MOS structure with preannealing fails at temperatures ~100°C higher than those without preannealing. By preannealing, oxygen and nitrogen were stuffed into the grain boundaries of the nanocrystalline films, thus eliminating the rapid diffusion path for copper. [Copyright &y& Elsevier]

Abstract: The influence of boron (B)/arsenic (As) on X-ray photoelectron spectroscopy (XPS) study of NiSi formation on shallow junctions is investigated in this paper. The Ni-silicide film was formed after 30s soak anneal at 450°C on ultra shallow p+/n or n+/p junctions. The atomic ratio of Ni/Si profile in depth was probed by XPS and the results show that a uniform NiSi layer forms on B-doped p+/n junction while a non-uniform, Ni-rich silicide layer forms on As-doped n+/p junction. It does not agree with the results of other independent phase identification methods such as X-ray diffraction, Rutherford backscattering spectroscopy, and Raman scattering spectroscopy, which all demonstrate the formation of NiSi on both n+/p and p+/n junctions. Comparing the raw binding energy spectra of Ni and Si for each silicide film, the similar spectra for Ni signals are revealed. But the Si signals with an obviously smaller intensity is found to be responsible for the apparent Ni rich silicide formation on As-doped n+/p junction. It indicates that As atoms in the silicide film can affect the sputtering yield of Ni and Si, while no noticeable effect is observed for B atoms. More As atoms than B atoms segregation into the silicide layer is indeed verified by secondary ion mass spectroscopy. And micro-Raman scattering spectroscopy further confirms that the degree of crystallinity for NiSi on n+/p junction is inferior to that on p+/n junction. [Copyright &y& Elsevier]

Amorphous Si0.87Ge0.13 is deposited on n-Si(100) substrate by ion beam sputtering (IBS) and doped through thermal diffusion of phosphorus to fabricate n-poly-Si0.87Ge0.13 thin film. The formation of Schottky junction is made by deposition Ni on n-poly-Si0.87Ge0.13 by IBS. Solid-phase reaction mainly occurred above 400 °C by rapid thermal annealing at the interface of Ni/n-poly-Si0.87Ge0.13. Phase identification and depth profile were investigated by X-ray diffraction (XRD) and Auger electron spectroscopy (AES), respectively. The electrical properties of both unannealed and annealed Ni/n-poly-Si0.87Ge0.13 were studied by current–voltage (I−V) measurement. The results demonstrate that the Schottky barrier height (SBH) changes little with the annealing temperature between 300 and 600 °C. The constancy of SBH is attributed to the properties of the interface itself which determine the SBH and substantially independent of whether the interfacial material is nickel or nickel germanosilicide. [Copyright &y& Elsevier]

Abstract: TaCN films were deposited using atomic layer deposition (ALD) using PDMAT and H2/Ar plasma. Calculations based on density functional theory (DFT) indicate a high energy barrier and a low reaction energy for reducing the +5 Ta oxidation state in the PDMAT precursor by using pure H radicals. Through the assistance of Ar radicals, low resistivity of TaCN films of 230μΩcm could be deposited by using H2/Ar plasma. By employing in situ X-ray diffraction during annealing, the activation energy for Cu diffusion through the TaCN barrier was evaluated at 1.6eV. [Copyright &y& Elsevier]

Abstract: The W-based diffusion barriers W, WC and WCN barriers were investigated for Cu metallization. The thermal stability of the W, WC and WCN barriers was compared by X-ray diffraction and four point probe. It shows comparable stability for the W and WC barriers while the ternary WCN barrier has superior performance. The agglomeration of the Cu films (100nm) on these barriers is quite different. The formation of voids was observed for the annealed copper film on the WC or WCN barriers and the activation energy values determined from Kissinger equation are low comparing with Cu on W barrier. Twins were also observed in the as-deposited and annealed Cu films on the WC and WCN barriers. The twin formation and its correlation with void formation for Cu films onto the C-containing diffusion barrier were discussed through the stress relaxation and stress-induced vacancy migration mechanism. [ABSTRACT FROM AUTHOR]

Abstract: Ru thin films were sequentially deposited onto TaN (5 nm) by plasma enhanced atomic layer deposition using Ru(EtCp)2 and NH3 as precursors. The effect of growth temperature on the electrical resistivity and morphology of the Ru films were studied. It was found that the Ru films can achieve a low resistivity of 14 µΩ cm and a low root-mean-square roughness at a growth temperature of 270 °C. The thickness of the underlying TaN film was found to affect the Ru film growth. The oxidation of the very thin TaN film was correlated with the island growth of Ru. Ex and in-situ X-ray diffraction was employed to verify the copper diffusion barrier properties of a Ru (3 nm)/TaN (5 nm) bi-layer structure. [Copyright &y& Elsevier]

Abstract: The thermal and electrical stabilities of Cu contact on NiSi substrate with and without a Ta/TaN barrier stack in between were investigated. Four-point probe (FPP), X-ray diffraction (XRD), scanning electron microscopy (SEM), depth-profiling X-ray photoelectron spectroscopy (XPS), and Schottky barrier height (SBH) measurement were carried out to characterize the diffusion barrier properties. The SBH measurement provides a very sensitive method to characterize the diffusion barrier properties for the copper contact on NiSi/Si. The results show that the Ta/TaN stack can be both thermally and electrically stable after annealing at 450°C for 30min and it will have a potential application as a diffusion barrier for Cu contact on NiSi. [Copyright &y& Elsevier]

Abstract: Thin Ru(5nm)/TaN(15nm) bi-layer was sputtered on the NiSi/Si substrate as a diffusion barrier in the copper contact structure. The barrier properties were investigated through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and electrical measurement. The whole Cu/Ru/TaN/NiSi/Si structure has a good thermal stability until after annealing at 450°C. The Schottky barrier measurement shows that the leakage current increases after 450°C annealing and after 500°C annealing the barrier fails. Failure mechanism of the barrier stack is discussed. [Copyright &y& Elsevier]