Electron Cyclotron Resonance Plasma Deposition Research Articles

Annealing effects on a-SiC:H and a-SiCN:H films deposited by plasma CVD methods

Hydrogenated amorphous silicon carbide (a-SiC:H) and carbonitride (a-SiCN:H) films were deposited in RF and mid-frequency (MF) discharges and electron cyclotron resonance (ECR) plasma. Annealing was performed in high vacuum up to 1000 °C and the temperature-dependent gas effusion from the films was investigated in situ by mass spectrometry. Changes of mechanical film properties, i.e. thickness, stress and Young's modulus, were determined ex situ by profilometry and nanoindentation, respectively. Using elastic recoil detection analysis, Rutherford backscattering and X-ray photoelectron spectroscopy, effects of annealing on elemental composition and chemical bonding were investigated. Annealing the a-SiC:H films significantly increased their Young's modulus and decreased their thickness by up to 25% in the case of ECR plasma deposition. The a-SiCN:H films deposited by MF and RF discharge practically retained their Young's modulus and the film thickness shrinkage was below 3%. At intermediate temperatures, these films showed a small thickness increase. For ECR-deposited a-SiCN:H, the expansion was larger and accompanied by a distinct reduction of Young's modulus. Hydrogen effusion and plastic flow under both compressive and tensile stress have a pronounced impact on the mechanical film properties. Annealing effects on film structure and properties are discussed and fundamental processes are derived.

Epitaxial Indium Tin Oxide Film Deposited on Sapphire Substrate by Solid-Source Electron Cyclotron Resonance Plasma

Indium tin oxide (ITO) thin films were epitaxially grown on sapphire substrates by solid-source electron cyclotron resonance (ECR) plasma deposition. Compared with the other methods such as sputtering and evaporation methods, the ECR plasma method resulted in a flat surface and a low resistivity with a relatively low substrate temperature. The surface roughness was strongly dependent on the ratio of oxygen gas flow during deposition. With optimal deposition conditions, the ITO thin film epitaxially grew on a c-plane sapphire substrate with twelvefold symmetry. The surface roughness and resistivity were estimated to be 0.4 nm and 1.4×10-4 Ω·cm, respectively. The X-ray rocking curve revealed 0.025° of full width at half maximum (FWHM) on the epitaxial ITO thin film. The ITO film deposited on an epitaxial GaN(001) layer on a c-plane sapphire substrate showed sixfold in-plane symmetry, indicating the epitaxial growth of ITO(111) on the GaN(001)/c-plane sapphire substrate.

Microcrystalline Si:H solar cells fabricated using ECR plasma deposition

The properties of microcrystalline Si:H materials and solar cells fabricated using remote, low pressure ECR (electron cyclotron resonance) plasma deposition are described. p+nn+ junction solar cells were deposited at 275–325°C on stainless steel substrates using mixtures of silane and hydrogen. Microcrystalline layers and solar cells could be produced even for low dilution ratio of hydrogen/silane of 8:1. It was found that once crystallisation started, one could decrease the hydrogen/silane ratio and still obtain microcrystalline Si:H solar cells. The voltage of the solar cells could be improved by tailoring the interface between p+ and n layers. An amorphous interfacial layer improved the voltage. A thin amorphous Si:H layer at the back, between n+ and n layers was used to significantly reduce the shunt resistance. Standard device analyses, including dark I(V) curves and capacitance measured at several frequencies, revealed that device characteristics could be understood in terms of a standard Si diode model. The doping densities in the n layer were found to be in the 1×1015 to 2×1016/cm3 range and could be adjusted by altering the amount of compensatory B doping of the layer. The influence of the addition of He dilution to the mixture was also studied, and it was found that He degraded the crystallinity, though it increased the growth rate and open-circuit voltage.

Zn-vapor diffused Er:Yb:LiNbO 3 channel waveguides fabricated by means of SiO 2 electron cyclotron resonance plasma deposition

We report here the fabrication method and operation of Zinc-vapor diffused channel waveguides on Erbium/Ytterbium (Er/Yb)-doped Lithium Niobate (LiNbO 3). electron cyclotron resonance (ECR) plasma deposition technique, UV photolithography and Reactive Ion Etching (RIE) are used to define an SiO 2 mask for pattern transfer. The whole process is performed at low temperatures eliminating typical LiO 2 out-diffusion problems and achieving low surface damage. The flexibility of the fabrication technology has been shown to be potentially applicable to integrated optics. EDAX measurements reveal good confinement and homogeneity of the diffused regions. Atomic Force Microscopy (AFM) surface characterization shows the swelling of the diffused areas, consistent with the topoepitaxial growth of a Zn x Li y Nb z O w layer.

Low temperature Electron Cyclotron Resonance plasma technique for low loss integrated optics

Electron Cyclotron Resonance (ECR) plasma deposition process implies low temperatures at high deposition rates producing uniform and mechanically stable thin films. For these reasons ECR became an attractive tool for integrated optics technology. In this work we have combined ECR with other techniques as Reactive lon Etching (RIE) and Pulsed Laser Deposition (PLD), in order to develop a new fabrication method of channel waveguides. We report here results on alumina-based strip-loaded waveguides. Amorphous Al 2O 3 core of 0.7 μm were deposited over Si/SiO 2 substrate by PLD technique and overcladded with a 0.5 μm SiO 2-ECR film. Standard UV-photolitographic techniques and RIE were used to define a set of strips on the SiO 2. These strips give the additional confinement of the light in the Al 2O 3 core. The optical losses at 633 nm were measured using an imaging technique. The relative scattered light power as function of the propagation along the channels shows a maximum optical loss of 4.5 dB/cm.

Plasma chemical vapor deposition of hydrocarbon films: The influence of hydrocarbon source gas on the film properties

Hydrocarbon films were prepared by electron cyclotron resonance plasma deposition from different hydrocarbon source gases at varying ion energies. The source gases used were the saturated hydrocarbons CH4, C2H6, C3H8, C4H10 (n- and iso-) and the unsaturated hydrocarbons C2H4 and C2H2 as well as mixtures of these gases with hydrogen. Film deposition was analyzed in situ by real-time ellipsometry, and the resulting films ex situ by ion-beam analysis. On the basis of the large range of deposition parameters investigated, the correlation between hydrocarbon source gas, deposition parameters, and film properties was determined. The film properties are found to be influenced over a wide range not only by the energy of the impinging ions, but also by the choice of source gas. This is in contrast to a widely accepted study where no dependence of the film properties on the source gas was observed, this being ascribed to a “lost-memory effect.” A strong correlation was found between the hydrogen content of the films and the film properties. This strong correlation is explained on the basis of the random-covalent-network model.

Assessment of as-deposited microcrystalline silicon films on polymer substrates using electron cyclotron resonance-plasma enhanced chemical vapor deposition

We have been successful in fabricating as-deposited microcrystalline silicon (μc-Si) on polyethersulfone and polyethylene terephthalate substrates and have assessed the characteristics of the Si films. We note that 13.5 MHz radio-frequency (rf) substrate bias during electron cyclotron resonance plasma deposition can be used to tailor the characteristics of these as-deposited μc-Si microcrystalline silicon films on the polymer substrates. As the rf substrate bias is applied and increased, as-deposited Si films loose their degree of crystallinity. At the same time, the activation energy of the Si film tends to be decreased and the intensity of the film photoluminescence (PL) is enhanced. Part of this increased PL intensity that is found with the addition of rf substrate bias occurs in a PL band at about 0.9 eV. This PL band in Si films may be attributed to the amorphous silicon (a-Si) materials.

Numerical simulation of plasma flow downstream in an ECR plasma deposition apparatus

The plasma flow along the divergent magnetic field of an electron cyclotron resonance (ECR) plasma source has been simulated. We assume that ions undergo charge exchange and elastic scattering collisions with the neutral gas in the downstream region. An iterative scheme for solution of the Boltzmann equation and quasineutrality has been developed, based on a Monte Carlo description for ion dynamics and reasonable data in our experimental device. We studied the effects of the magnetic field configuration and neutral gas pressure on the plasma potential, density distribution along a divergent magnetic field, and the ion flux density and energy incident on a substrate. The numerical simulated results have been compared with the experimental data measured by using Langmuir probe in our ECR plasma chemical vapor deposition system.

Effect of negative rf bias on electrophotographic properties of hard diamond-like carbon films deposited on organic photoconductors

Hard diamond-like carbon (DLC) films were prepared on organic photoconductor (OPC) and PMMA (polymethyl methacrylate) samples by electron cyclotron resonance (ECR) plasma deposition with low substrate bias. The films exhibited a specific electrical resistivity above and very high transmittance for the visible spectrum of 370-800 nm. The hardness of the OPC samples was increased at least fourfold after deposition of DLC films. The acceptance voltage, photodischarge rate and dark decay rate of the DLC-coated OPC samples were all improved, and reached optimal values for rf biases around . The results indicated that the deposition of hard DLC films on OPC is a very promising technique to lengthen the working lifetimes of the OPC materials.

A Silicon Oxide Antireflective Layer For Optical Lithography Using Electron Cyclotron Resonance Plasma Deposition

Using electron cyclotron resonance plasma deposition, we have developed an SiOx film as an antireflective layer (ARL) for the gate process of LSI fabrication by i-line and KrF lithography. The ARL is an absorption type and is 100 nm thick. The estimated optimum optical properties of the ARL for i-line were n=2.3–2.6 and k=0.5–0.6. For KrF, they were n=1.8–2.1 and k=0.5–0.6. An SiOx film having these properties can be reproducibly deposited at SiH4/O2 gas flow rate ratio of 1.3 for i-line and 1.1 for KrF. The chemical compositions of the films are SiO0.5 for i-line and SiO1.0 for KrF. The SiO0.5 film was used as an i-line ARL for 0.35-µ m LSI gate fabrication and superior process performance and sufficient critical dimension controllability (variation within 19 nm of 3σ) were obtained.

Properties of a-SiN x .: H films deposited at room temperature by the electron cyclotron resonance plasma method

Abstract a-SIN x :H films with a wide composition range (0·27≤×≤1·38), and some of them with low oxygen content, have been deposited at room temperature by the electron cyclotron resonance plasma deposition method. Auger electron spectro-scopy, infrared absorption, and transmittance and reflectance of the films in the ultraviolet/visible/near-infrared range are reported. Three different types of film are obtained: silicon rich, near stoichiometric and oxygen contaminated. At x =1·00, the hydrogen content, calculated from the infrared spectra, is a minimum (about 10 at.%), the N-H bond density becomes higher than the Si[sbnd]H density, and the slope of the Tauc plot (B) and the Urbach tail (E u), obtained from absorption coefficient results, reach minimum and maximum values, respectively. Hydrogen incorporation into the network is found to be related to that of nitrogen. A relationship between the hydrogen content and the optical properties of the films is deduced by comparing the results with those publis...

Epitaxial film thickness in the low-temperature growth of Si(100) by plasma enhanced chemical vapor deposition

The limiting epitaxial thickness of Si films grown at a low substrate temperature by plasma enhanced chemical vapor deposition has been determined. The specific process used was electron cyclotron resonance plasma deposition. The limiting epitaxial thickness was found to decrease with the ratio of energetic ion-to-adatom arrivals on the substrate surface. The measured epitaxial thicknesses are similar to those obtained in previous investigations using molecular beam epitaxy. Hydrogen surface coverage does not appear to be a factor in limiting epitaxial thickness. The maximum epitaxial thickness remains to be determined for this process and substrate temperature range.

Fabrication of thickness-controlled silicon nanowires and their characteristics

A process for fabricating thin Si nanowires is proposed which can reduce the parasitic series resistance of the nanowire. The process includes electron cyclotron resonance plasma deposition of a SiO2 film through the openings of a patterned resist film. Since the SiO2 thickness decreases as the opening narrows, the SiO2 film can be made thinnest in the nanowire region. Therefore, during the following reactive-ion etching, the SiO2 film in this region is removed first and the Si layer is then selectively etched. A Si nanowire fabricated through this process shows quantized conductance at temperatures as high as 200 K.

Charge build-up reduction during biased electron cyclotron resonance plasma deposition

A technique to reduce charge buildup causing gate-oxide deterioration during biased electron cyclotron resonance (ECR) plasma deposition has been developed. For SiO2 planarization and filling techniques, it is necessary to resolve the charge build-up phenomenon with the biased ECR plasma system. The deterioration is reduced by adjusting the magnet-coil position in the ECR plasma system which means minimizing the magnetic-flux density at the specimen surface.

A novel setup for spectroscopic ellipsometry using an acousto-optic tuneable filter

A rotating-analyzer ellipsometer for fast measurements at multiple wavelengths as well as for spectroscopic measurements has been developed. The most important novelty of the setup is the use of an acousto-optic tuneable filter (AOTF) as dispersing element. This offers advantages with respect to the speed of measurement, the adjustment of the intensity of the light, the use of lock-in techniques, and the stability and size of the setup. Advantages and limitations of the use of AOTF’s in ellipsometry as well as possible changes in the ellipsometric setup are discussed. The ellipsometer has been mounted on an electron cyclotron resonance plasma deposition chamber. As an example, the deposition of amorphous hydrogenated carbon layers has been studied in situ and are compared to ex situ measurements by variable angle of incidence spectroscopic ellipsometry of the same samples.

Surface Morphology and Microstructure of Al-O Alloys Grown by ECR Plasma Deposition

AbstractThe growth of polycrystalline and amorphous aluminum-oxygen alloy films using electronbeam evaporation of Al in the presence of an O2 electron-cyclotron-resonance (ECR) plasma was investigated for film compositions varying from 40% Al (A12O3) to near 100% Al (A1Ox). Processing parameters such as deposition temperature and ion energy were varied to study their effects on surface texture and film microstructure. The Al-rich films (AlOx) contain polycrystalline fcc Al grains with finely dispersed second-phase particles of γ-A12O3 (1–2 nm in size). The surface roughness of these films was measured by atomic force microscopy and found to increase with sample bias and deposition temperature. Stoichiometric A12O3 films grown at 100°C and 400°C without an applied bias were amorphous, while an applied bias of -140 V formed a nanocrystalline γ-A12O3 film at 400°C. The surface roughness of the A12O3 increased with temperature while ion irradiation produced a smoother surface

Electron cyclotron resonance plasma deposition and etching of silicon nitride on GaSb for optoelectronic applications

Silicon nitride thin films were deposited by electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition on GaSb substrates using SiH 4 and N 2 gaseous sources. In order to obtain SiN x films able to bear stress during thermal process steps, such as implantation or diffusion annealing, the maximum thickness of the SiN x layer which remains stable after annealing at a temperature of 510°C was estimated by changing two growth parameters: substrate temperature and deposition rate. The layer grown at room temperature sticks well when the thickness is below 50 nm and, when the layer is grown at 370°C, it remains stable up to 150 nm thick. However, the critical thickness of the SiN x layer is rather insensitive to the deposition rate in the range 1–4 nm min −1. Patterning on these structures is performed by an r.f. biased ECR plasma etching CF 4/O 2 process.

Low pressure microwave electron cyclotron resonance plasma deposition of amorphous Ta2O5 films

Deposition of Ta2O5 from Ta(OC2H5)5 and O2 has been studied using a distributed electron cyclotron resonance plasma. Carbon contamination levels as low as 1.5% have been obtained when the Ta(OC2H5)5 vapor is introduced ‘‘downstream’’ away from the plasma volume. Electrical measurements (current density/voltage, capacitance/voltage) suggest the films have dielectric constants ∼22 and leakage currents ∼10−10 A cm−2 for 2 V operation (50 nm thick, 10 nm a-SiO2 equivalent). These values are obtained without the necessity for high temperature annealing and recrystallization. The conduction mechanism is attributed to the Poole–Frenkel effect.

Comment on “Search for carbon nitride CN x compounds with a high nitrogen content by electron cyclotron resonance plasma deposition”, Diamond relat. mater., 3 (1994) 264–269

Comment on “Search for carbon nitride CN x compounds with a high nitrogen content by electron cyclotron resonance plasma deposition”, Diamond relat. mater., 3 (1994) 264–269

Electron cyclotron resonance plasma deposition as a promising technique for low-temperature hard coatings

Si 3N 4 and SiC films have been deposited by electron cyclotron resonance (ECR) plasma at low substrate temperature (T s ⩽150°C). Films prepared by this new technique exhibited better properties than those deposited by other plasma methods. Different gas ratios and microwave powers have been used. The films have been analysed by infrared spectrometry and spectroscopic ellipsometry. Si 3N 4 and SiC films show in general a good thickness homogeneity (< 4% in 3 in. wafers) and reproducibility. Depending on the process parameters we have found growth rates up to 3500 Åmin −1 for Si 3N 4 and 400 Åmin −1 for SiC. The infrared spectra of these layers have shown no signal of SiH and NH bonds in the Si 3N 4 films and low traces of SiH and CH n bonds in the SiC films.