Showing papers on "Chemical vapor deposition published in 2001"

Growth process conditions of vertically aligned carbon nanotubes using plasma enhanced chemical vapor deposition

Abstract: The growth of vertically aligned carbon nanotubes using a direct current plasma enhanced chemical vapor deposition system is reported. The growth properties are studied as a function of the Ni catalyst layer thickness, bias voltage, deposition temperature, C2H2:NH3 ratio, and pressure. It was found that the diameter, growth rate, and areal density of the nanotubes are controlled by the initial thickness of the catalyst layer. The alignment of the nanotubes depends on the electric field. Our results indicate that the growth occurs by diffusion of carbon through the Ni catalyst particle, which rides on the top of the growing tube.

Composition and Microstructure of Cobalt Oxide Thin Films Obtained from a Novel Cobalt(II) Precursor by Chemical Vapor Deposition

Abstract: The present work reports the synthesis and the characterization of cobalt oxide thin films obtained by chemical vapor deposition (CVD) on indium tin oxide (ITO) substrates, using a cobalt(II) β-diketonate as precursor. The complex is characterized by electron impact mass spectrometry (EI-MS) and thermal analysis in order to investigate its decomposition pattern. The depositions are carried out in a cold wall reactor in the temperature range 350−500 °C at different oxygen pressures, to tailor film composition from CoO to Co3O4. The crystalline nanostructure is evidenced by X-ray diffraction (XRD), while the surface and in-depth chemical composition is studied by X-ray photoelectron (XPS) and X-ray excited auger electron spectroscopy (XE-AES). Atomic force microscopy (AFM) is employed to analyze the surface morphology of the films and its dependence on the synthesis conditions. Relevant results concerning the control of composition and microstructure of Co−O thin films are presented and discussed.

Colloidal crystal templating of three-dimensionally ordered macroporous solids: materials for photonics and beyond

Abstract: This review discusses strategies for the synthesis of three-dimensionally ordered macroporous (3DOM) solids (inverse opals) by colloidal crystal templating. Compositions of 3DOM structures include simple and ternary oxides, chalcogenides, non-metallic and metallic elements, hybrid organo-silicates, and polymers. A wide range of 3DOM synthesis techniques, including sol–gel chemistry, polymerization, salt-precipitation and chemical conversion, chemical vapor deposition, spray pyrolysis, ion spraying, laser spraying, nanocrystal deposition and sintering, oxide and salt reduction, electrodeposition, electroless deposition, fabrication from core-shell spheres, and patterning methods, as well as templating using inverse opal molds to produce new opal compositions are reviewed. Potential uses of 3DOM solids, including photonic crystal, optical, catalytic, and bioglass applications are briefly discussed.

Synthesis and characterization of highly-conducting nitrogen-doped ultrananocrystalline diamond films

Abstract: Ultrananocrystalline diamond (UNCD) films with up to 0.2% total nitrogen content were synthesized by a microwave plasma-enhanced chemical-vapor-deposition method using a CH4(1%)/Ar gas mixture and 1%–20% nitrogen gas added. The electrical conductivity of the nitrogen-doped UNCD films increases by five orders of magnitude (up to 143 Ω−1 cm−1) with increasing nitrogen content. Conductivity and Hall measurements made as a function of film temperature down to 4.2 K indicate that these films have the highest n-type conductivity and carrier concentration demonstrated for phase-pure diamond thin films. Grain-boundary conduction is proposed to explain the remarkable transport properties of these films.

Metalorganic vapor-phase epitaxial growth and photoluminescent properties of Zn1−xMgxO(0⩽x⩽0.49) thin films

Abstract: High-quality Zn1−xMgxO(0.00⩽x⩽0.49) thin films were epitaxially grown at 500–650 °C on Al2O3(00⋅1) substrates using metalorganic vapor-phase epitaxy. By increasing the Mg content in the films up to 49 at. %, the c-axis constant of the films decreased from 5.21 to 5.14 A and no significant phase separation was observed as determined by x-ray diffraction measurements. Furthermore, the near-band-edge emission peak position showed blueshifts of 100, 440, and 685 meV at Mg content levels of 9, 29, and 49 at. %, respectively. Photoluminescent properties of the alloy films are also discussed.

Ti-catalyzed Si nanowires by chemical vapor deposition: Microscopy and growth mechanisms

Abstract: Si nanowires grow rapidly by chemical vapor deposition on Ti-containing islands on Si surfaces when an abundant supply of Si-containing gaseous precursor is available. The density of wires is approximately the same as the density of the nucleating islands on the Si surface, although at least two different types of islands appear to correlate with very different wire growth rates. For the deposition conditions used, a minority of long, defect-free wires form, along with more numerous wires containing defects. Energy-dispersive x-ray spectroscopy shows that the Ti-containing nanoparticles remain at the tip of the growing wires. The estimated diffusion coefficient of Si in TiSi2 is consistent with the catalyzing nanoparticle remaining in the solid phase during nanowire growth.

Copper interconnect barrier layer structure and formation method

Abstract: A method for forming a tungsten-containing copper interconnect barrier layer (e.g., a tungsten [W] or tungsten-nitride [WxN] copper interconnect barrier layer) on a substrate with a high (e.g., greater than 30%) sidewall step coverage and ample adhesion to underlying dielectric layers. The method includes first depositing a thin titanium-nitride (TiN) or tantalum nitride (TaN) nucleation layer (12) on the substrate, followed by the formation of a tungsten-containing copper interconnect barrier layer (20) (e.g., a W orWxN copper interconnect barrier layer) overlying the substrate. The tungsten-containing copper interconnect barrier layer can, for example, be formed using a Chemical Vapor Deposition (CVD) technique that employs a fluorine-free tungsten-containing gas (e.g., tungsten hexacarbonyl [W(CO)6]) or a WF6-based Atomic Layer Deposition (ALD) technique. The presence of a thin TiN (or TaN) nucleation layer facilitates the formation of a tungsten-­containing copper interconnect barrier layer with a sidewall step coverage of greater than 30% and ample adhesion to dielectric layers. A copper interconnect barrier layer structure includes a thin titanium-nitride (TiN) (or tantalum nitride [TAN]) nucleation layer disposed directly on the dielectric substrate (e.g., a single or dual-damascene copper interconnect dielectric substrate). The copper interconnect barrier layer structure also includes a tungsten-­containing copper interconnect barrier layer (e.g., a W or WxN copper interconnect barrier layer) formed on the thin TiN (or TaN) nucleation layer using, for example, a CVD technique that employs a fluorine-free tungsten-containing gas (e.g., [W(CO)6]) or a WF6-based ALD technique.

Properties of high κ gate dielectrics Gd2O3 and Y2O3 for Si

Abstract: We present the materials growth and properties of both epitaxial and amorphous films of Gd2O3 (κ=14) and Y2O3 (κ=18) as the alternative gate dielectrics for Si. The rare earth oxide films were prepared by ultrahigh vacuum vapor deposition from an oxide source. The use of vicinal Si (100) substrates is key to the growth of (110) oriented, single domain films in the Mn2O3 structure. Compared to SiO2 gate oxide, the crystalline Gd2O3 and Y2O3 oxide films show a reduction of electrical leakage at 1 V by four orders of magnitude over an equivalent oxide thickness range of 10–20 A. The leakage of amorphous Y2O3 films is about six orders of magnitude better than SiO2 due to a smooth morphology and abrupt interface with Si. The absence of SiO2 segregation at the dielectric/Si interface is established from infrared absorption spectroscopy and scanning transmission electron microscopy. The amorphous Gd2O3 and Y2O3 films withstand the high temperature anneals to 850 °C and remain electrically and chemically intact.

Organosilicon precursors for interlayer dielectric films with low dielectric constants

Abstract: A method of forming a low dielectric constant interlayer dielectric film on a substrate by reacting, under chemical vapor deposition conditions sufficient to deposit the film on the substrate, an organosilicon precursor comprising a silyl ether, a silyl ether oligomer, or an organosilicon compound containing one or more reactive groups, to form an interlayer dielectric film having a dielectric constant of 3.5 or less. The films formed by the above method.

Thin film forming method

Abstract: A method for forming thin films of a semiconductor device is provided. The thin film formation method presented here is based upon a time-divisional process gas supply in a chemical vapor deposition (CVD) method where the process gases are supplied and purged sequentially, and additionally plasma is generated in synchronization with the cycle of pulsing reactant gases. A method of forming thin films that possess a property of gradient composition profile is also presented.

Effect of catalyst film thickness on carbon nanotube growth by selective area chemical vapor deposition

Abstract: The correlation between prepatterned catalyst film thickness and carbon nanotube (CNT) growth by selective area chemical vapor deposition (CVD) was studied using Fe and Ni as catalyst. To eliminate sample-to-sample variations and create a growth environment in which the film thickness is the sole variable, samples with continuously changing catalyst film thickness from 0 to 60 nm were fabricated by electron-gun evaporation. Using thermal CVD CNTs preferentially grow as a dense mat on the thin regions of the catalyst film. Moreover, beyond a certain critical film thickness no tubes were observed. The critical film thickness for CNT growth was found to increase with substrate temperature. There appears to be no strong correlation between the film thickness and the diameter of the tubes. In contrast, using plasma enhanced CVD with Ni as catalyst, vertically oriented CNTs grow in the entire range of catalyst film thickness. The diameter of these CNTs shows a strong correlation with the catalyst film thickness. The significance of these experimental trends is discussed within the framework of the diffusion model for CNT growth.

Thermal stability of ultrathin ZrO2 films prepared by chemical vapor deposition on Si(100)

Abstract: As a function of thermal treatment, the chemical stability of ultrathin ZrO2 films prepared by chemical vapor deposition on a silicon substrate is investigated by x-ray photoelectron spectroscopy. The chemical structure is stable up to 800 °C in both vacuum and N2 ambient, but a reaction forming zirconium silicide occurs above 900 °C in vacuum. The formation of silicide is accounted for by a reaction mechanism involving a reaction of ZrO2 with SiO, the latter formed above 900 °C at the interface between Si(100) and the thin layer of SiO2 formed during growth of the ZrO2.

Gap fill for high aspect ratio structures

Abstract: Chemical vapor deposition processes are employed to fill high aspect ratio (typically at least 3:1), narrow width (typically 1.5 microns or less and even sub 0.15 micron) gaps with significantly reduced incidence of voids or weak spots. This deposition process involves the use of hydrogen as a process gas in the reactive mixture of a plasma containing CVD reactor. The process gas also includes dielectric forming precursor molecules such as silicon and oxygen containing molecules.

Ultralow-k dielectrics prepared by plasma-enhanced chemical vapor deposition

Abstract: Carbon-doped oxide materials (SiCOH films) with ultralow dielectric constants have been prepared by plasma-enhanced chemical vapor deposition (PECVD) from mixtures of SiCOH precursors with organic materials. The films have been characterized by Rutherford backscattering and forward recoil elastic scattering analysis, Fourier transform infrared spectroscopy and index of refraction measurements, and measurement of step heights in the films. The electrical properties of the films have been measured on metal–insulator–silicon structures. By proper choice of the precursor and deposition conditions, the dielectric constants of the SiCOH films can be reduced to values below 2.1, demonstrating the extendibility of PECVD-prepared carbon-doped oxides as the interconnect dielectrics for future generation of very large scale integrated chips.

Nanolayer thick film processing system and method

Abstract: A process to deposit a thin film by chemical vapor deposition includes evacuating a chamber of gases; exposing a device to a gaseous first reactant, wherein the first reactant deposits on the device to form the thin film having a plurality of monolayers in thickness; evacuating the chamber of gases; exposing the device, coated with the first reactant, to a gaseous second reactant under a plasma treatment, wherein the thin film is treated by the first reactant; and repeating the previous steps.

Electrical and materials properties of ZrO2 gate dielectrics grown by atomic layer chemical vapor deposition

Abstract: Structural and electrical properties of gate stack structures containing ZrO2 dielectrics were investigated. The ZrO2 films were deposited by atomic layer chemical vapor deposition (ALCVD) after different substrate preparations. The structure, composition, and interfacial characteristics of these gate stacks were examined using cross-sectional transmission electron microscopy and x-ray photoelectron spectroscopy. The ZrO2 films were polycrystalline with either a cubic or tetragonal crystal structure. An amorphous interfacial layer with a moderate dielectric constant formed between the ZrO2 layer and the substrate during ALCVD growth on chemical oxide-terminated silicon. Gate stacks with a measured equivalent oxide thickness (EOT) of 1.3 nm showed leakage values of 10−5 A/cm2 at a bias of −1 V from flatband, which is significantly less than that seen with SiO2 dielectrics of similar EOT. A hysteresis of 8–10 mV was seen for ±2 V sweeps while a midgap interface state density (Dit) of ∼3×1011 states/cm eV wa...

Method for low temperature chemical vapor deposition of low-k films using selected cyclosiloxane and ozone gases for semiconductor applications

Abstract: A method is described for forming a low-k dielectric film, in particular, a pre-metal dielectric (PMD) on a semiconductor wafer which has good gap-filling characteristics. The method uses a thermal sub-atmospheric CVD process that includes a carbon-containing organometallic precusor such as TMCTS or OMCTS, an ozone-containing gas, and a source of dopants for gettering alkali elements and for lowering the reflow temperature of the dielectric while attaining the desired low-k and gap-filling properties of the dielectric film. Phosphorous is a preferred dopant for gettering alkali elements such as sodium. Additional dopants for lowering the reflow temperature include, but are not limited to boron, germanium, arsenic, fluorine or combinations thereof.

Method of forming metal nitride film by chemical vapor deposition and method of forming metal contact and capacitor of semiconductor device using the same

Abstract: A method of forming a metal nitride film using chemical vapor deposition (CVD), and a method of forming a metal contact and a semiconductor capacitor of a semiconductor device using the same, are provided. The method of forming a metal nitride film using chemical vapor deposition (CVD) in which a metal source and a nitrogen source are used as a precursor, includes the steps of inserting a semiconductor substrate into a deposition chamber, flowing the metal source into the deposition chamber, removing the metal source remaining in the deposition chamber by cutting off the inflow of the metal source and flowing a purge gas into the deposition chamber, cutting off the purge gas and flowing the nitrogen source into the deposition chamber to react with the metal source adsorbed on the semiconductor substrate, and removing the nitrogen source remaining in the deposition chamber by cutting off the inflow of the nitrogen source and flowing the purge gas into the deposition chamber. Accordingly, the metal nitride film having low resistivity and a low content of Cl even with excellent step coverage can be formed at a temperature of 500° C. or lower, and a semiconductor capacitor having excellent leakage current characteristics can be manufactured. Also, a deposition speed, approximately 20 A/cycle, is suitable for mass production.

Method of manufacturing a barrier metal layer using atomic layer deposition

Abstract: A method of manufacturing a barrier metal layer uses atomic layer deposition (ALD) as the mechanism for depositing the barrier metal. The method includes supplying a first source gas onto the entire surface of a semiconductor substrate in the form of a pulse, and supplying a second source gas, which reacts with the first source gas, onto the entire surface of the semiconductor substrate in the form of a pulse. In a first embodiment, the pulses overlap in time so that the second source gas reacts with part of the first source gas physically adsorbed at the surface of the semiconductor substrate to thereby form part of the barrier metal layer by chemical vapor deposition whereas another part of the second source gas reacts with the first source gas chemically adsorbed at the surface of the semiconductor substrate to thereby form part of the barrier metal layer by atomic layer deposition. Thus, the deposition rate is greater than if the barrier metal layer were only formed by ALD. In the second embodiment, an impurity-removing gas is used to remove impurities in the barrier metal layer. Thus, even if the gas supply scheme is set up to only use ALD in creating the barrier metal layer, the deposition rate can be increased without the usual accompanying increase in the impurity content of the barrier metal layer.

Chemical vapor deposition of barriers from novel precursors

Abstract: The present invention provides a method and precursor for forming a metal and/or metal nitride layer on the substrate by chemical vapor deposition. The organometallic precursor has the formula of (Cp(R)n)xMHy-x, where Cp is a cyclopentadienyl functional group, R is a substituent on the cyclopentadienyl functional group comprising an organic group having at least one carbon-silicon bond, n is an integer from 0 to 5, x is an integer from 1 to 4, M is a metal, and y is the valence of the metal M. A metal, metal nitride, metal carbon nitride, or metal silicon nitride film (118; 119) is deposited on a heated substrate (112) by thermal or plasma enhanced decomposition of the organometallic precursor in the presence of a processing gas, such as hydrogen, nitrogen, ammonia, silane, and combinations thereof, at a pressure of less than about 26.66 hPa (20 Torr). By controlling the reactive gas composition either metal or metal nitride films may be deposited. The deposited metal or metal nitride film (118; 119) may then be exposed to a plasma to remove contaminants, densify the film, and reduce film resistivity.

Patterned selective growth of carbon nanotubes and large field emission from vertically well-aligned carbon nanotube field emitter arrays

Abstract: We have grown well-aligned carbon nanotube arrays by thermal chemical vapor deposition at 800 °C on Fe nanoparticles deposited by a pulsed laser on a porous Si substrate. We also attain a selective growth of carbon nanotubes on a patterned Fe film on Si substrates in terms of pulsed laser deposition and a liftoff patterning method. Field emission measurement has been made on the carbon nanotube (CNT)-cathode diode device at room temperature and in a vacuum chamber below 10−6 Torr. The distance between the CNT cathode and the anode is 60 μm and is kept through an insulating spacer of polyvinyl film. The measured field emitting area is 4.0×10−5 cm2. Our vertically well-aligned carbon nanotube field emitter arrays on the Si-wafer substrate emit a large current density as high as 80 mA/cm2 at 3 V/μm. The transmission electron microscope image shows that they are multiwalled and bamboolike structures and that the tips of some of the carbon nanotube emitters are open. The open tip structure of our CNTs and thei...

Chemical vapor deposition using organometallic precursors

Abstract: A multi-component layer is deposited on a semiconductor substrate in a semiconductor process The multi-component layer may be a dielectric layer formed from a gaseous titanium organometallic precursor, reactive silane-based gas and a gaseous oxidant The multi-component layer may be deposited in a cold wall or hot wall chemical vapor deposition (CVD) reactor, and in the presence or absence of plasma The multi-component layer may also be deposited using other processes, such as radiant energy or rapid thermal CVD

Patterned growth of single-walled carbon nanotubes on full 4-inch wafers

Abstract: Patterned growth of single-walled carbon nanotubes (SWNTs) is achieved on full 4-in. SiO2/Si wafers. Catalytic islands with high uniformity over the entire wafer are obtained by a deep ultraviolet photolithography technique. Growth by chemical vapor deposition of methane is found to be very sensitive to the amount of H2 co-flow. Understanding of the chemistry enables the growth of high quality SWNTs from massive arrays (107–108) of well-defined surface sites. The scale up in patterned nanotube growth shall pave the way to large-scale molecular wire devices.

Optical gain at 1.54 μm in erbium-doped silicon nanocluster sensitized waveguide

Abstract: Optical gain at 1.54 μm in erbium-doped silicon-rich silicon oxide (SRSO) is demonstrated. Er-doped SRSO thin film was fabricated by electron-cyclotron resonance enhanced chemical vapor deposition of silicon suboxide with concurrent sputtering of erbium followed by a 5 min anneal at 1000 °C. Ridge-type single mode waveguides were fabricated by wet chemical etching. Optical gain of 4 dB/cm of an externally coupled signal at 1.54 μm is observed when the Er is excited via carriers generated in the Si nanoclusters by the 477 nm line of an Ar laser incident on the top of the waveguide at a pump power of 1.5 W cm−2.

Metalorganic chemical vapor deposition of GaN on Si(111): Stress control and application to field-effect transistors

Abstract: Two schemes of nucleation and growth of gallium nitride on Si(111) substrates are investigated and the structural and electrical properties of the resulting films are reported. Gallium nitride films grown using a 10–500 nm-thick AlN buffer layer deposited at high temperature (∼1050 °C) are found to be under 260–530 MPa of tensile stress and exhibit cracking, the origin of which is discussed. The threading dislocation density in these films increases with increasing AlN thickness, covering a range of 1.1 to >5.8×109 cm−2. Films grown using a thick, AlN-to-GaN graded buffer layer are found to be under compressive stress and are completely crack free. Heterojunction field effect transistors fabricated on such films result in well-defined saturation and pinch-off behavior with a saturated current of ∼525 mA/mm and a transconductance of ∼100 mS/mm in dc operation.

Tantalum nitride CVD deposition by tantalum oxide densification

Abstract: The invention provides a method for forming a metal nitride film by depositing a metal oxide film on the substrate and exposing the metal oxide film to a nitrating gas to densify the metal oxide and form a metal nitride film. The metal oxide film is deposited by the decomposition of a chemical vapor deposition precursor. The nitrating step comprises exposing the metal oxide film to a thermally or plasma enhanced nitrating gas preferably comprising nitrogen, oxygen, and ammonia. The invention also provides a process for forming a liner/barrier scheme for a metallization stack by forming a metal nitride layer over the substrate by the densification of a metal oxide layer by a nitrating gas depositing a metal liner layer. Optionally, a metal liner layer may be deposited over substrate prior to the metal nitride layer to forma metal/metal nitride liner/barrier scheme. The invention further provides a process to form a microelectronic device comprising forming a first electrode, forming a metal nitride layer over the first electrode by densifying a metal oxide layer by a nitrating gas to form a metal nitride layer, depositing a dielectric layer over the metal nitride layer, and forming a second electrode over the dielectric layer. Alternatively, the metal nitride film may comprise the first and second electrodes.