1,721,181 research outputs found
CHEMICAL-VAPOR-DEPOSITION OF ALUMINUM FOR ULSI APPLICATIONS
No full textAluminum has been used widely as a conducting material in the fabrication of integrated circuits, and chemical vapor deposition process for Al has been actively investigated for the application in ultra large scale integration. In this review, various precursors, mainly alkyl aluminum and alane compounds, and reaction mechanisms of these precursors in Al CVD are described. Epitaxial growth and selectivity of the deposition are also discussed. In addition to thermal reactions, plasma and photochemical reactions are also briefly described.X114sciescopu
Cyclic atomic layer deposition of hafnium aluminate thin films using tetrakis(diethylamido)hafnium, trimethyl aluminum, and water
No full textHafnium aluminate thin films were deposited at 225 degrees C by cyclic atomic layer deposition (ALD) of hafnia and alumina with Hf(N(C2H5)(2))(4) (tetrakis(diethylamido)hafnium: TDEAH), Al(CH3)(3) (trimethyl aluminum: TMA), and H2O. The multi-component thin films were formed by switching between the alumina and hafnia deposition cycles, and the chemical composition of the film was controlled by adjusting the number of cycles of each oxide. The surface of the film was very smooth and the formation of an interfacial layer was suppressed. The crystallization temperature of the film became higher as the Al incorporation in the film was increased. The hafnium aluminate thin film with the composition Hf0.68Al0.32Ox showed a dielectric constant of 1.3.94 and leakage current of 4.3 x 10(-7) A cm(-2) at 1 MV cm(-1). At this composition, the formation of an interfacial layer was minimal after rapid thermal annealing (RTA).X117sciescopu
Experimental and theoretical study of step coverage in metal-organic chemical vapor deposition of tantalum oxide thin films
No full textThe chemical vapor deposition of tantalum oxide thin films from pentaethoxy tantalum on to trench structures was conducted to investigate experimentally the step coverage and to compare these results with simulated findings. The dependence of the step coverage on the substrate temperature and the type of carrier gas was evaluated experimentally, and the sticking coefficient was determined from the comparison of the experimental results with the simulation. Deposition at low temperatures using He carrier gas gives better step coverage with the tantalum oxide thin film. A comparison of the activation energy associated with the sticking coefficient with the activation energy associated with the deposition rate on a blank wafer surface using He and Ar carrier gases was made. The step coverage with He was determined from the deposition rate, while the step coverage with Ar was determined using the Knudsen diffusion rate of reactant inside the trench.X1122sciescopu
Electrical properties of bulk silicon dioxide and SiO2/Si interface formed by tetraethylorthosilicate-ozone chemical vapor deposition
No full textSilicon oxide films have been deposited with chemical vapor deposition from TEOS/O-3 at low temperature below 400 degrees C for the gate insulator of thin-film transistors. The electrical properties of the bulk silicon oxide film and the SiO2/Si interface were investigated as a function of process parameters such as deposition temperature and TEOS/O-3 ratio using capacitance-voltage and current-voltage measurements. The breakdown strength increased and the leakage current decreased as the deposition temperature increased, but both were not significantly dependent on the TEOS/O-3 ratio. The breakdown strength of the film deposited at 380 degrees C was about 5 MV/cm. As the deposition temperature increased, the interface trap density (D-it) at Si midgap was almost constant, but D-it near E-v + 0.25 eV and E-v + 0.75 eV, which is the P-b center, decreased. The interface trap density was lowest when the TEOS/O-3 ratio was 0.35. It was confirmed that the deposition temperature influenced the electrical properties of the bulk oxide and the interface, but the TEOS/O-3 ratio affected only the interface properties. (C) 2000 The Electrochemical Society. S0013-4651(99)07-045-7. All rights reserved.open1140sciescopu
Deposition of NiOx thin films with radio frequency magnetron sputtering and their characteristics as a source/drain electrode for the pentacene thin film transistor
No full textNiOx films were deposited with radio frequency (rf) magnetron sputtering at various sputtering powers (25-300 W) and deposition temperatures (room temperature to 200 degrees C) using NiO target and pure O-2 as a sputtering gas. Crystallinity, bonding state (Ni+3 and Ni+2), work function, and the resistivity of the film were measured and the performance of the pentacene thin film transistor (TFT) with the NiOx film as a source/drain (S/D) electrode was evaluated. The film properties such as roughness, work function, crystallinity, and bonding state of Ni and O were similar at each sputtering power, and the NiOx film was deposited at around 150 W and room temperature showed lower resistivity of 1.34x10(4) mu Omega cm, lower surface roughness of 0.206 nm, and higher work function of 5.2 eV. With the increase in the deposition temperature, the ratio of Ni2+ ions to Ni3+ ions in the NiOx film was increased, the work function was decreased and the resistivity was increased. A pentacene TFT with NiOx film deposited at 150 W and room temperature showed a device performance better than that with gold film, with mobility of 0.178 cm(2)/V s, threshold voltage of 0.34 V, and on/off ratio of 5.0x10(5). (C) 2008 American Vacuum Society.open111515sciescopu
Microstructure and interfacial states of silicon dioxide film grown by low temperature remote plasma enhanced chemical vapor deposition
No full textThe properties of SiO2 film and the Si/SiO2 interface formed by remote plasma enhanced chemical vapor deposition with the addition of chlorine into SiH4-N2O have been investigated. With the chlorine addition, the deposition rate increased at low deposition temperatures but at temperatures above 150 degrees C, it decreased because of the desorption of surface halide species. Chlorine at the Si/SiO2 interface prevented further subcutaneous oxidation and formed strong, terminal site Si-Cl bonds which reduced the interface state density. The substitution reaction of O and H with Cl in the bulk oxide film leads to a disordered film structure and decreased hydrogen concentration. The surface roughness increased and the refractive index decreased with increased Cl-2 addition. With chlorine addition of less than 6 vol %, the interface trap density (located at similar to E-upsilon + 0.3-0.4 eV) significantly decreased down to the 1-3 X 10(11) eV cm(2) level at the Si midgap. At high chlorine partial pressure and temperature, the local interface trap density (located at similar to E-upsilon + 0.7-0.8 eV) increased due to increased structural disorder resulting from breakage of the Si-O bond. (C) 1999 American Institute of Physics. [S0021-8979(99)07714-2].open1120sciescopu
Bulk and interface properties of low-temperature silicon nitride films deposited by remote plasma enhanced chemical vapor deposition
No full textHydrogenated silicon nitride (a-SiNx: H) films were deposited at temperatures ranging from 50 to 300 degreesC with remote plasma enhanced chemical vapor deposition (RPECVD) from NH3 and SiH4. The effect of the operating variables, such as deposition temperature and especially the partial pressure ratio of reactant (R = NH3/SiH4) on the properties of the SiNx : H films and the Si/SiNx: H interface was investigated. The NH* radical was dominantly observed and the deposition rate was proportional to the NH* radical concentration. The density of highly energetic N*(2) radicals increased in the high plasma power regime in which the film surface was roughened, but they promote surface reactions even at low temperature. The refractive index was more closely related to the film stoichiometry than film density. The interface trap density is related to the amount of silicon intermediate species and Si-NH bonds at the Si/SiNx: H interface and it can be minimized by reducing the intermediate Si species and Si-NH bonding state. The films showed a midgap interface trap density of 2 x 10(11) - 2 x 10(12) cm(-2). (C) 2001 Kluwer Academic Publishers.X1160sciescopu
Low temperature silicon dioxide film deposition by remote plasma enhanced chemical vapor deposition: growth mechanism
No full textDeposition mechanism of SiO2 film growth from SiH4-N2O by remote plasma enhanced chemical vapor deposition (RPECVD) has been studied. An inductively coupled-RPECVD system was used to deposit films at the temperature of 25-350 degreesC and deposition pressure of 0.4 Torr. From in situ gas phase analyses and film composition, we suggested the film deposition mechanism and main precursors. The gas phase species including hydrogen, oxygen and SiHx fragments are incorporated into the SiO2 film as the film precursors. SiH3, SiH2 and O* radicals are likely main gas phase species for precurosor formation. In particular, the formation and transport of silanols (SiH2O and SiH3O) are observed and oxidation mechanism of these radicals is discussed. While surface hydrogen-related bonds are observed, they can be effectively removed by surface oxidation reaction. Surface composition of deposited films is similar with gas phase species and hydrogen bonds at the growing surface can be eliminated by oxygen plasma and charged ion bombardment. At high plasma power, the deposition rate is saturated and drops off, while the density of oxidation species in the plasma continuously increases. Surface roughness of deposited films increased and shows power-law dependence on plasma power. (C) 2003 Elsevier B.V. All rights reserved.X1112sciescopu
EFFECT OF PRECURSORS ON THE COMBUSTION SYNTHESIS OF TIC-AL2O3 COMPOSITE
No full textIn the combustion synthesis of TiC-Al2O3 composites from TiO2, Al, and C, different types of precursors, i.e., anatase and rutile TiO2, and graphite and carbon black were used. The measurements of combustion wave velocity showed that the reactivity was higher with graphite as a carbon source and anatase as a TiO2 source. This was also confirmed by analyzing the degree of conversion of reactants to products. For the precursors investigated, the wave propagation of the 3TiO2-4Al-3C system diluted by Al2O3 showed that the limit of wave propagation was more dependent on carbon source than on TiO2. The wave front of all the samples proceeded in unstable combustion mode. Temperature profiles in the reaction zone suggested that the heat-affected zone was broader in the case of graphite carbon source than carbon black. The microstructures and chemical composition of the products were also studied.X1115sciescopu
Optoelectronic properties of fluorine-doped silicon nitride thin films
No full textPlasma-enhanced chemical vapor deposition (PECVD) of fluorine-doped silicon nitride (SiNx:F) has been investigated with a small amount of tetrafluorosilane (SiF4) added into the SiH4-NH3 gas mixture. The influence of preparation conditions on the optical and electrical properties of the SiNx:F films has been systematically studied by XPS, FT-IR and UV-visible spectroscopy for optical property and current-voltage ramping measurement for electron conduction mechanism. It has been found that low radio frequency plasma power and the appropriate amount of SiF4 addition favor the improvement of film properties to minimize the side effect for high quality film deposition such as etching effect from the dissociated SiFx and F radicals. Remarkably, deposition rate and optical band gap are higher than that in SiH4-NH3 gas chemistry even in the case of NHx radical deficient deposition conditions. SiNx:F films have lower hydrogen content and show rather rough and porous microstructure. However, the improvement of dielectric property can be obtained with high optical band gap (similar to5.5 eV), resistivity (>10(17)Omegacm) and barrier height (>1.6eV) for the trapped electron conduction even in the Si-rich nitride films. (C) 2004 Published by Elsevier B.V.X117sciescopu
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