Showing papers on "Plasma-enhanced chemical vapor deposition published in 1989"

Low temperature selective crystallization of amorphous silicon

Abstract: We have used rapid thermal annealing to crystallize PECVD a-Si:H films deposited on glass at low thermal budgets of 700°C/4 min. The a-Si:H films can be selectively crystallized using thermal budgets lower than 700°C/4min. by selectively depositing an ultrathin Pd layer on the silicon surface. We have investigated the electrical and the structural properties of these selectively crystallized films.

Low temperature organometallic deposition of metals

Abstract: A process for coating metal on a substrate. The process uses organometallic compounds such as (trimethyl)(cyclopentadienyl) platinum in the presence of a reducing fluid such as hydrogen gas to produce high purity films capable of selective deposition on substrates containing, for example, tungsten and silicon. The films are deposited using chemical vapor deposition (CVD) or gas phase laser deposition. The invention also comprises devices made from the process of the invention.

In situ ellipsometry of thin‐film deposition: Implications for amorphous and microcrystalline Si growth

Abstract: Real‐time ellipsometric characterization of the nucleation of hydrogenated amorphous silicon (a‐Si:H) prepared by plasma‐enhanced chemical vapor deposition (PECVD) on smooth, dense metal, and crystalline Si substrates is reviewed. The experimental results for photoelectronic quality a‐Si:H from pure SiH4 on Mo and Cr are consistent with the Volmer–Weber nucleation mode, with a separation of 40–50 A between nucleation centers. For c‐Si substrates, a new interpretation suggests that nucleation occurs on the same scale, but the geometry in the first monolayer is disklike. A well‐defined lobe and cusp in the data can be ascribed to surface smoothening by diffusion that results upon coalescence of these structures. For films from a pure SiH4 plasma, the rates of coalescence and relaxation of substrate‐induced surface roughness on thick films are consistent with a diffusion length of ∼80 A for the adsorbed precursors. For films prepared from a SiH4‐depleted plasma, the average surface diffusion length is reduce...

Silicon nitride thin films prepared by the electron cyclotron resonance plasma chemical vapor deposition method

Abstract: Silicon nitride thin films prepared by the electron cyclotron resonance plasma chemical vapor deposition method at low substrate temperature ( 1017 Ω⋅cm and >10 MV/cm, respectively. These properties of silicon nitride thin films are close to those of stoichiometric silicon nitride (Si3N4) prepared by the thermal chemical vapor deposition method at high temperature (>600 °C). The interface trap state density between the silicon nitride film and silicon substrate was 4×1011 cm2/eV in the silicon band gap. An optical emission spectroscopy during the deposition indicated that the intensities of nitrogen molecular ions were much stronger than those of nitrogen molecules, and the silane was sufficiently decomposed into silicon and hydrogen atoms. It is consider...

Surface hydrogen content and passivation of silicon deposited by plasma induced chemical vapor deposition from silane and the implications for the reaction mechanism

Abstract: A systematic study of the enhanced concentration of hydrogen in the near surface layer of silicon deposited from silane by plasma induced chemical vapor deposition is presented as a function of temperature and ion bombardment of the surface during growth. The passivation effect of the chemisorbed hydrogen towards oxidation of the surface is documented, and a possible explanation is suggested in terms of a donatorlike effect of that hydrogen to underlying silicon. It is shown that the rate limiting step in the composite reaction mechanism of the deposition of high‐quality silicon films is the ion bombardment induced dehydrogenation of the surface of the growing film. A critical value of substrate bias of −100 eV with respect to the floating potential at which radiation induced damage of the growing film commences is found experimentally. The corresponding ion impact energy agrees very well with Monte Carlo calculations using the TRIM code.

Chemical Vapor Deposition of Epitaxial Silicon from Silane at Low Temperatures I . Very Low Pressure Deposition

Abstract: The deposition of epitaxial silicon films at temperatures from 600°–800°C by both very low‐pressure chemical vapor deposition (VLPCVD) and plasma‐enhanced chemical vapor deposition (PECVD) has been examined. The VLPCVD deposition process is first order in silane partial pressure, zero order in hydrogen partial pressure, and exhibits a low, 8–12 kcal/ mole, activation energy for temperatures from 700°–800°C with 1–15 mtorr silane and hydrogen. For temperatures below 700°C an activation energy of 40 kcal/mole is observed. The growth rate depends upon surface orientation, decreasing in the order (100), (111), polycrystalline, indicating surface processes are rate controlling. The low activation energy regime is associated with a process controlled by silane adsorption and decomposition on a sparsely covered silicon surface. The higher activation energy regime is thought to reflect growth under conditions of high surface coverage with silane fragments and the transition temperature is thought to be pressure dependent. Conditions for the deposition of device quality epitaxial silicon at low temperatures are defined and discussed. Plasma enhancement of the VLPCVD process is discussed in a companion paper.

Silicon nitride produced by catalytic chemical vapor deposition method

Abstract: The catalytic chemical vapor deposition method is applied to obtain silicon nitride insulating films usable in large‐scale integrated circuits. A N2 H4, N2 , and SiH4 gas mixture is decomposed by the catalytic or pyrolytic reaction with a heated catalyzer placed near substrates, and thus silicon nitride films are deposited at low temperatures around 300 °C with deposition rates higher than several hundreds A/min, without any help from plasma and photochemical excitation. It is found that the resistivity, the breakdown electric field, and also the hydrogen content of the films can be almost equivalent to those of the films deposited by the thermal chemical vapor deposition at 700 °C or more, and that their step coverage appears sufficient to apply them on device fabrication.

Deposition of silicon oxide films using alkylsilane liquid sources

Abstract: A chemical vapor deposition process for depositing silicon dioxide comprising the steps of heating a substrate upon which deposition is desired to a temperature of from about 325° C. to about 700° C. in a vacuum having a pressure of from about 0.1 to about 1.5 torr, and introducing a silane selected from the group consisting of alkylsilane, arylsilane and araylkylsilane wherein the alkyl-, aryl- or aralkyl- moiety comprises from 2-6 carbons, and oxygen or carbon dioxide into the vacuum.

Homoepitaxial films grown on Si (100) at 150 °C by remote plasma‐enhanced chemical vapor deposition

Abstract: Low‐temperature silicon epitaxy is critical for future generation ultralarge scale integrated circuits and silicon‐based heterostructures. Remote plasma‐enhanced chemical vapor deposition has been applied to achieve silicon homoepitaxy at temperatures as low as 150 °C, which is believed to be the lowest temperature reported to date. Critical to the process are an in situ remote plasma hydrogen cleaning of the substrate surface in an ultrahigh vacuum growth chamber prior to epitaxy, and substitution of thermal energy by remote plasma excitation via argon metastables and energetic electrons to dissociate silane and increase adatom mobility on the surface of the silicon substrate. Excellent crystallinity with very few defects such as dislocations and stacking faults is observed.

Method of producing carbon-doped amorphous silicon thin film

Abstract: A method of producing a carbon-doped amorphous silicon thin film upon a substrate comprising the steps of growing a carbon-doped amorphous silicon layer by plasma assisted chemical vapor deposition, including generating a glow discharge in a gaseous mixture of a silane gas and a hydrocarbon gas, and exposing said carbon-doped amorphous silicon layer to a plasma in a gas containing hydrogen to achieve a resultant layer having a prescribed value of photoconductivity.

Low‐temperature deposition of silicon dioxide films from electron cyclotron resonant microwave plasmas

Abstract: Silicon dioxide films were deposited on crystalline silicon substrates by electron cyclotron resonant (ECR) microwave plasma‐enhanced chemical vapor deposition (PECVD). Films were grown on Si〈100〉 substrates at temperatures of 140–600 °C, flow rates of 0.5–10 sccm SiH4, 10–30 sccm O2, and at a pressure of 10−3 Torr. Infrared absorption spectroscopy of the samples indicated no detectable SiH, OH, or SiOH groups. Neither an afterglow chemistry nor He dilution was required to eliminate H impurities as was previously reported for silicon oxide films deposited from rf plasmas. This suggests that significant differences exist between rf and ECR microwave plasma chemistries. We have found that the stoichiometry and index of refraction was not sensitive to oxidant ratio for a wide range of conditions in contrast to other studies. Stoichiometric SiO2 films, with good physical properties, were grown for a much wider range of oxidant ratios relative to those which are characteristic of the rf PECVD technique. In add...

Stability of electrical properties of nitrogen-rich, silicon-rich, and stoichiometric silicon nitride films

Abstract: Metal‐nitride‐silicon capacitors were used to explore the stability of the electrical properties of silicon nitride films of various stoichiometries Silicon‐rich silicon nitride films were found to display a large and symmetric hysteresis loop in the capacitance‐voltage curve, a large flat‐band voltage shift approximately symmetric with respect to the polarity of the voltage under bias temperature stress, and a current density‐voltage characteristic which is approximately symmetric with respect to polarity It is argued that in these silicon‐rich silicon nitride films the dominant defects are silicon dangling bonds which can trap either electrons or holes A different class of behavior was observed, however, for nitrogen‐rich silicon nitride films deposited by plasma enhanced chemical vapor deposition These films have a much smaller and asymmetric hysteresis loop in the capacitance‐voltage curve, an asymmetric flat‐band voltage shift under bias temperature stress, and an asymmetric current density‐volta

Process for forming planarized films

Abstract: A planarization process and apparatus which employs plasma-enhanced chemical vapor deposition (PECVD) to form plarnarization films of dielectric or conductive carbonaceous material on step-like substrates.

Tribological properties of diamond films grown by plasma‐enhanced chemical vapor deposition

Abstract: Uniform and continuous diamond films have been deposited on Si, Mo, and many other substrates by plasma‐enhanced chemical vapor deposition. We have developed processes to enhance the adhesion of diamond films to metal substrates for tribological applications. The tribological properties of the diamond films are found to be significantly different depending on their morphology, grain size, and roughness. However, under all cases tested using a ring‐on‐block tribotester, it is found that for diamond films with a small grain size of 1–3 μm, the coefficient of friction of the diamond films sliding against a steel ring under lubrication of a jet of mineral oil is about 0.04.

Atomic structure in SiO2 thin films deposited by remote plasma‐enhanced chemical vapor deposition

Abstract: We have studied selected structure‐dependent properties of thin films of SiO2 prepared by remote plasma‐enhanced chemical vapor deposition (remote PECVD) and thermal oxidation of crystalline silicon, and have identified process‐dependent differences in their local atomic structures. We have determined the frequency ν and linewidth Δν of the Si–O bond‐stretching infrared‐active vibration near 1075 cm−1, and have found that all relatively thick oxide films, t>1000 A, prepared by either of these two techniques display the same linear relationship between Δν and ν. This behavior has been interpreted in terms of a central force model that gives the average bond angle 2θ at the oxygen atom sites, and attributes the linewidth to a distribution of vibration modes associated with a ±30° spread in 2θ. We have determined that (i) in remote PECVD films deposited at temperatures (Ts ) between 200 and 350 °C, 2θ varies between 140° and 144°; (ii) in thermal oxides grown over a temperature range (Tox ) between 800 and 1...

Electron cyclotron resonance plasma stream source for plasma enhanced chemical vapor deposition

Abstract: An electron cyclotron resonance (ECR) plasma stream source at a frequency of 2.45 GHz was explored and utilized for SiO2 film chemical vapor deposition (CVD). It was found that for high and uniform plasma stream density the large limiting ring and magnetic fields higher than 930 G are required in the ECR plasma chamber. Plasma densities of(4–6)×1010 cm−3 in nitrogen and (6–8)×1011 cm−3 in argon with uniformities of ±5% over an area of 12 cm in diameter were achieved at distances of 30 to 50 cm from the source limiting ring at a microwave power range of 500 to 600 W. The etch of thermal silicon dioxide and polysilicon with CF4 showed uniformity better than ±1% over 5‐in. wafers at a distance of 19 cm. SiO2 films were deposited in a mixture of 15% SiH4/N2 and O2 at substrate temperatures of 30 to 200 °C. Room‐temperature ECR films had characteristics better than those obtained in conventional plasma enhanced CVD films deposited at 300 °C. ECR films deposited at 200 °C had properties which approach those of ...

Process for the chemical vapor deposition of aluminum

Abstract: A method for forming aluminum films is provided comprising employing the techniques of chemical vapor deposition to thermally decompose a vapor comprising a aluminum hydride subsequent to the treatment of the substrate with a Group IVB or VB metal complex, so as to deposit a mirror-like coating of aluminum on the surface of a substrate.

Method of controlling the chemical structure of polymeric films by plasma

Abstract: A method of controlling the chemical structure of thin films formed by plasma deposition and films produced by these methods, is disclosed. An important aspect of the method involves controlling the temperature of the substrate and the reactor so as to create a temperature differential between the substrate and reactor such that the precursor molecules are preferentially adsorbed or condensed onto the substrate either during plasma deposition or between plasma deposition steps. The thin films produced by the methods of this invention exhibit more defined and predictable chemical structures and properties than conventional plasma deposited films.

Vapor deposition method for simultaneously growing an epitaxial silicon layer and a polycrystalline silicone layer over a selectively oxidized silicon substrate

Abstract: A method for simultaneously forming an epitaxial silicon layer on a surface of a silicon substrate, and a polysilicon layer on a silicon dioxide (SiO 2 ) layer which is formed on the silicon substrate using a low pressure silicon vapor deposition method, employing silicon hydride gas, particularly disilane (Si 2 O 6 ), as a silicon source gas. A crystal growing temperature ranging from 780° C. to 950° C. and a reaction gas pressure ranging from 20 Torr to 300 Torr are desirable. An extended silicon epitaxial region is achieved under a higher temperature and a higher gas pressure, and with a substrate of a (100) orientation. A polysilicon layer having an even surface and joining smoothly to an epitaxial silicon layer which is simultaneously formed, is obtained under a lower temperature and a lower gas pressure, and with a substrate of a (111) orientation.

Influence of exposure to an atmosphere of high relative humidity on tribological properties of diamondlike carbon films

Abstract: ‘‘Diamondlike’’ carbon films have potential applications because of their high wear resistances. We have investigated the influence of exposure to an atmosphere of high relative humidity (RH) on tribological properties of carbon films prepared with a radio‐frequency plasma enhanced chemical vapor deposition. Wear characteristics were measured using a pin‐on‐disk wear tester. A friction coefficient of a carbon film as deposited was as low as 0.2. However, the value increased up to 0.3–0.4 after exposure to an atmosphere of 60 °C 90% RH for seven days. Electron spectroscopy for chemical analysis and electron energy‐loss spectroscopy analysis suggested that a very thin (<1 nm) unstable surface layer of the film had suffered a chemical change during the exposure process. We have found that the change can be suppressed by increasing a degree of fragmentation of the hydrocarbon source in the plasma, or by removing the unstable layer with an Ar plasma etching.

Multipole confined diffusion plasma produced by 13.56 MHz electrodeless source

Abstract: An inductively coupled rf plasma source is shown to produce a large uniform diffusion plasma at low pressures in a reactor surrounded externally by small magnets arranged to produce cusp fields at the walls. Electron densities of >1011 cm−3 can be produced at pressures of <10−3 Torr argon with 800 W input power. With SF6 ion currents of 0.5 mA cm−2 uniform to ±1.5% over 15 cm diameter have been measured at 6×10−4 Torr and 400 W.

Plasma‐Enhanced Chemical Vapor Deposition of Silicon Dioxide Using Tetraethylorthosilicate (TEOS)

Abstract: This paper presents a study on plasma‐assisted chemical vapor deposition of silicon dioxide films using tetraethylorthosilicate (TEOS). It was found that when oxygen is utilized as an oxidant, the resulting film contained approximately 1 atom percent (a/o) of nitrogen or carbon, whereas using in the reaction slightly increased the nitrogen concentration to 2 a/o. However, in the absence of oxidant, the carbon and nitrogen concentrations were approximately 18 and 6 a/o, respectively. The step coverage of the film, regardless of the oxidant, was approximately 34%, a substantial improvement compared to the 10% obtained for oxide films deposited using silane‐based chemistry. The refractive index, infrared spectrum, and film density appear characteristic of deposited films. The electrical characterization of the films yielded a breakdown electric field greater than 6.6 MV/cm, and a leakage current density of at 1 MV/cm. The breakdown electric field and leakage current density of a thermally grown oxide with comparable thickness are 8 MV/cm and , respectively.

Gas/surface reactions in the chemical vapor deposition of tungsten using WF6/SiH4 mixtures

Abstract: We have studied the surface reactions of WF6/SiH4 mixtures on Si(100) that are relevant to the chemical vapor deposition of tungsten using x‐ray photoemission and molecular‐beam reactive scattering. The overall reaction is found to be 3SiH4+2WF6→2W+3SiF4+6H2 with very little production of HF. The reaction proceeds by repeating the cycle of tungsten deposition by the reaction of WF6 with silicon, and the deposition of silicon by the reaction of SiH4 with the fluorinated tungsten surface.

Preparation of BaF2 films by metalorganic chemical vapor deposition

Abstract: To date thin films of II(a) fluorides (CaF2, BaF2, SrF2, and their mixtures) have only been deposited by physical vapor deposition techniques. We report for the first time the deposition of BaF2 films on silicon and yttrium‐stabilized zirconia substrates by metalorganic chemical vapor deposition at a substrate temperature as low as 400 °C.

Optical emission and mass spectroscopic studies of the gas phase during the deposition of SiO2 and a‐Si:H by remote plasma‐enhanced chemical vapor deposition

Abstract: This paper will present mass spectrometric and optical emission spectroscopic studies of the deposition process of amorphous hydrogenated silicon (a‐Si:H) and silicon dioxide (SiO2) by remote plasma‐enhanced chemical vapor deposition (remote PECVD). We have established that the silane reactant, which is not directly exposed to a rf plasma in either of the deposition processes, is not fragmented or chemically combined in the gas phase. Specifically there is no evidence for the formation of disilane, Si2H6, or siloxanes or silanols in the gas phase, as in the direct PECVD process. In the case of the a‐Si:H depositions, the silane is excited in the gas phase and the excited species, SiH*4 , is the deposition precursor. In the case of the SiO2 depositions, the active species promoting deposition is an O2 metastable neutral molecule. The by‐products of the respective reactions are H2 and H2O.

Plasma Metalorganic Chemical Vapor Deposition of Indium Oxide Thin Films

Abstract: Indium oxide (In2O3) thin films were obtained from trimethylindium and O2 by the plasma metalorganic chemical vapor deposition method (MOCVD). A d.c. glow discharge was used to make the plasma. At a substrate temperature above 200°C, polycrystalline thin films were obtained, while no film was obtained by thermal MOCVD without plasma at the substrate temperature used in this study (<360°C). The transmittance and resistivity of the film depended on the molar ratio of trimethylindium and O2.

Simulation of the bulk and surface properties of amorphous hydrogenated silicon deposited from silane plasmas

Abstract: A Monte Carlo simulation for the growth of amorphous hydrogenated silicon (a‐Si:H) thin films by plasma enhanced chemical vapor deposition is presented. The goal of the model is to predict the bulk and surface properties of films (e.g., hydrogen content, deposition rate, buried hydride/dihydride ratios, porosity, and surface roughness) having thicknesses of ≲2000 A. The effects on the film properties of the composition of the radical flux incident on the surface are examined. Film properties were found to be critically dependent on the ratio of SiH3/SiH2 in the radical flux. High values for this ratio results in film properties resembling chemical vapor deposition. Film properties obtained with small values resemble physical vapor deposition. Rough films (roughness >10’s of A) accordingly result from radical fluxes having high SiH2 fractions. We find that surface roughness and hydrogen fraction increase with increasing growth rate and increasing film thickness, though thin films (<10’s of layers) have lar...

Plasma-enhanced chemical vapor deposition of in situ doped epitaxial silicon at low temperatures. I. Arsenic doping

Abstract: In situ arsenic doping of epitaxial silicon films deposited from 700 to 800 °C by both very‐low‐pressure chemical vapor deposition (VLPCVD) and plasma‐enhanced chemical vapor deposition (PECVD) has been investigated. The growth rate and morphology of films deposited by silane VLPCVD are degraded in the presence of arsine. The overall activation energy for deposition increases and the apparent silane reaction order decreases relative to VLPCVD in the absence of arsine. VLPCVD arsenic incorporation depends sublinearly on the arsine partial pressure and appears to saturate for incorporation fractions above 1018 As atoms/cm3. PECVD growth rates are less sensitive to arsine, and plasma enhancement is seen to provide significant advantages for n‐type doping of epitaxial silicon at low temperatures. PECVD deposits show an order‐of‐magnitude increase in active dopant incorporation, exhibit superior morphology relative to VLPCVD, and allow for increased doping flexibility. Incorporation remains proportional to ars...