Electron Cyclotron Resonance Plasma CVD Research Articles

ECR plasma deposited a-SiCN:H as insulating layer in piezoceramic modules

Highly resistive and sufficiently stiff insulation layers are an important prerequisite for the direct integration of piezoceramic modules into microstructured aluminium alloy sheets to produce smart adaptronic metal parts. In this study, we evaluate the mechanical and electrical properties of amorphous, hydrogenated silicon carbonitride films (a-SiCN:H) deposited by electron cyclotron resonance plasma CVD. First, we find the optimal process parameters for silicon substrates which we then transfer to electroded lead zirconate titanate (PZT) plates. Deposition rate, Young's modulus, stoichiometry and resistivity of a-SiCN:H films are determined by stylus profilometry, nanoindentation, X-ray photoelectron spectroscopy, elastic recoil detection analysis and current-voltage measurements, respectively. Under a 100 kHz bipolar pulsed substrate bias, 2 … 3 μm thick, well insulating films with Young's modulus ≈100 GPa are deposited at high rate of up to 7 μm/h. The electrical performance of a-SiCN:H films on PZT substrates is, to large extent, governed by the size and number of PZT roughness peaks, locally enhancing the field strength. Furthermore, we briefly address the deposition of the electrode layer on PZT. The selected material, sputter-deposited CuCr1Zr alloy, considerably improves the fracture strength of PZT substrates.

Bias-independent growth of carbon nanowalls by microwave electron-cyclotron resonance plasma CVD

The investigations reported here describe the synthesis of carbon nanowalls (CNWs) by microwave electron-cyclotron resonance (ECR) plasma-assisted chemical vapour deposition (PACVD) process without an application of external bias to the substrate during growth. CNWs were grown on silicon (Si) substrates using hydrogen (H2)/methane (CH4) plasma at 650°C substrate temperature. Nickel (Ni) was used as a catalyst for the synthesis of CNWs. To the best of our knowledge, this is the first report that describes the bias-independent growth of CNWs using the ECR PACVD process. Formation of CNWs is confirmed by scanning electron microscopy and Raman spectroscopy. The discussion part also includes a possible growth mechanism for CNWs in terms of the role of surface plasmons.

Plasma emission diagnostics during fast deposition of microcrystalline silicon thin films in matrix distributed electron cyclotron resonance plasma CVD system

AbstractThe structural and optoelectronic properties of undoped hydrogenated microcrystalline silicon (μ c‐Si:H) films deposited in a matrix distributed electron cyclotron resonance (MDECR) plasma CVD system using pure silane were studied as a function of microwave power (PMW) and gas pressure (Pgas). The analysis of the silane plasma optical emission spectra (OES) shows the effect of the deposition conditions on the plasma chemistry and resulting film microstructure as studied by spectroscopic ellipsometry and atomic force microscopy. The use of the PMW and Pgas as tunable parameters to achieve μ c‐Si:H films with desired microstructure is discussed. Intrinsic μ c‐Si:H films with good phototransport properties were realized at high deposition rate. Our study shows the usefulness of OES as a fast diagnostic tool for controlling and optimizing the μ c‐Si:H deposition process in MDECR reactor. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Microwave ECR plasma CVD of cubic Y2O3 coatings and their characterization

Abstract Yttrium oxide (Y2O3) thin films are deposited by microwave electron cyclotron resonance (ECR) plasma assisted metal organic chemical vapour deposition (MOCVD) process at a substrate temperature of 350 °C using indigenously developed metal organic precursors (2,2,6,6-tetra methyl-3,5-heptane dionate) yttrium, commonly known as Y(thd)3 synthesized by ultrasound method. The deposited coatings are characterized by X-ray photoelectron spectroscopy, glancing angle X-ray diffraction, scanning electron microscopy, EDS and infrared spectroscopy. The characterization results indicate that it is possible to deposit non-porous coatings with excellent uniformity of a single phase cubic Y2O3 on various substrates by this process at reasonably low substrate temperature that is desirable in various manufacturing processes.

Substrate bias effects during diamond like carbon film deposition by microwave ECR plasma CVD

Abstract Diamond like carbon (DLC) coatings were deposited on silicon(1 1 1) substrates by microwave electron cyclotron resonance (ECR) plasma CVD process using a plasma of Ar and CH4 gases under the influence of DC self bias generated on the substrates by application of RF (13.56 MHz) power. DLC coatings were deposited under the varying influence of DC bias (−60 V to −150 V) on the Si substrates. Deposited films were analyzed by different techniques like: X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), atomic force microscopy (AFM), Hardness and elastic modulus determination technique, Raman spectroscopy, scanning electron microscopy (SEM) and contact angle measurement. The results indicate that the film grown at −100 V bias has optimised properties like high sp3/sp2 ratio of carbon bonding, high refractive index (2.26–2.17) over wide spectral range 400–1200 nm, low roughness of 0.8 nm, high contact angle (80°) compared to the films deposited at other bias voltages (−60 V and −150 V). The results are consistent with each other and find august explanation under the subplantation model for DLC growth.

Dark and illuminated characteristics of crystalline silicon solar cells with ECR plasma CVD deposited emitters

The dark and illuminated I–V characteristics of simple, p–n junction crystalline silicon solar cells having microcrystalline or epitaxial emitters have been studied at various temperatures. Low temperature (<600°C) ECR (electron cyclotron resonance) plasma-assisted CVD has been used to deposit the emitter layers. The two-diode solar cell model has been used to fit the I–V characteristics and extract cell parameters such as diode ideality factors, saturation currents and shunt resistances. Overall, it is found that the two-diode model describes the data well and microcrystalline emitter devices with similar performance to epitaxial emitter cells can be realized. The spectral response data shows that in addition to optical losses (associated with the lack of anti-reflective surfaces and the emitter thickness), surface and emitter recombination play a significant part in limiting the performance of these devices.

Depth resolved comparative investigation of phase formation and stress build-up in cubic boron nitride films

Cubic boron nitride films have been deposited by means of ion beam assisted deposition (IBAD) and electron cyclotron resonance plasma CVD. Specially designed silicon cantilever substrates were used which allow precise stress measurements. After deposition, the films were etched back in steps of approximately 5–20 nm by Ar ions. After each step, the stress, the thickness and also FTIR spectra were measured. By this means, the stress distribution, the development of the c-BN content and also the thicknesses of the h-BN nucleation layer and the transition layer h-BN → c-BN could be determined. Major differences were found between the two types of layers: IBAD films possess a nucleation layer with a thickness of 15–20 nm and a stress of approximately 3 GPa. After c-BN nucleation, a transition region of approximately 20 nm is observed in which the c-BN content rapidly increases to the final value, which can exceed 90%. However, the c-BN top layer possesses a high compressive stress with values up to 20 GPa. In contrast, for ECR films the transition from the h-BN nucleation layer to the c-BN top layer is much more gradual (nucleation layer thickness approx. 50 nm). Simultaneously, the c-BN content of the top layer is limited to approximately 70% while its stress is much lower (2–3 GPa). The reasons for these differences in phase formation and stress build-up are discussed in terms of the differences between the two techniques.

Thin base-layer single crystal silicon solar cells with ECR plasmaCVD grown emitters

Thin (~16 µm) base-layer monocrystalline silicon solarcells have been investigated with microcrystalline or epitaxial n-typeemitters grown at low temperatures ({<}550 °C) by electron cyclotronresonance (ECR) plasma-enhanced chemical vapour deposition (PECVD). Thep-type, 1-2 Ωcm, base layers were epitaxially deposited byconventional thermal CVD onto monocrystalline Si p+ substrates. Anefficiency of 13.72% was achieved in the best epitaxial emitter cell afterECR hydrogen passivation and the application of a SiNx anti-reflectioncoating deposited by ECR PECVD. Cells with microcrystalline Si emittersprocessed in a similar fashion gave a maximum efficiency of 10.73%. The cellperformance was analysed using the two-diode model and the solar cellmodelling programme PC-1D. The results are presented. It was necessary toinvoke a three-layer PC-1D model to obtain self-consistent fits to the lightand dark I-V characteristics and spectral response data.

Low temperature growth of p-type crystalline silicon films by ECR plasma CVD

We report on the growth of thick (up to 4 μm) p-type crystalline silicon films on silicon from silane using the technique of electron cyclotron resonance (ECR) plasma-assisted chemical vapour deposition (PACVD) at temperatures <700 °C. Epitaxial growth was obtained at ~ 680 °C for growth rates in the region of 25 nm/min. At lower temperatures the films are microcrystalline with varying degrees of crystallinity depending on growth conditions.

A comparative study of boron and phosphorus doping effects in SiC : H films prepared by electron cyclotron resonance plasma CVD

Hydrogenated silicon carbide films (SiC : H) were deposited using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique from a mixture of methane, silane and hydrogen, using diborane and phosphine as doping gases. The effects of changes in the microwave power on the deposition rate and optical bandgap were investigated, and variations in the photo- and dark conductivities and activation energy were studied in conjunction with film analysis, using the Raman scattering technique. In the case of boron-doped samples, the conductivity increased rapidly to a maximum, followed by rapid reduction at high microwave powers. The ratio of photo- to dark conductivity (σph/σd) peaked at a microwave power of ~ 600 W. Under conditions of high microwave power, Raman scattering analysis showed evidence of the formation and increase in the silicon microcrystalline and diamond-like phases in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity. In the case of phosphorus-doped SiC : H samples, it was found that an increase in the microwave power has the effect of enhancing the formation of the silicon microcrystalline phase in the films; this occurred in correspondence to a rapid increase in the conductivity and a reduction in the activation energy. The conductivity increase stabilized in samples deposited at microwave powers exceeding 500 W, probably as a result of dopant saturation. Results from Raman scattering measurements also showed that phosphorus doping has the effect of enhancing the formation of the silicon microcrystals in the film whereas the presence of boron has the effect of preserving the amorphous structure.

Low Temperature Growth of Crystalline Silicon Thin Films by ECR Plasma CVD

AbstractCrystalline silicon films have been deposited on silicon and metal-coated coming 7095 glass substrates at temperatures of 280 ˜ 680°C by electron cyclotron resonance (ECR) plasma assisted chemical vapor deposition (PACVD) using an ultrahigh vacuum chamber and SiH4 as the feedstock. X-ray diffraction (XRD), Raman spectroscopy, Rutherford backscattering (RBS) and secondary ion mass spectrometry (SIMS) have been used to characterize the films. At temperatures of ˜280 °C, the as-grown films are microcrystalline with crystalline fractions between 50–97%. From XRD patterns, randomly oriented crystalline silicon grains were clearly present in the films with the grain sizes estimated to be between 170 – 370Å. As the growth temperature is increased to 470°C, epitaxial growth on silicon is observed at growth rates of 240Å/min without bias or hydrogen plasma treatment before film growth. N-type doping of the layers has been achieved using PH3 as the doping gas and solar cells with ECR grown emitters fabricated on 15μm thick p-type epilayers on p+ substrates.

Dominant radicals in electron cyclotron resonance plasma CVD

The dominant radicals for growth of a-Si:H films in electron cyclotron resonance plasma chemical vapour deposition have been investigated by analysing the film coverage on a trench. The profile of the film prepared from radicals produced in the gas phase was simulated by a Monte Carlo method using a sticking probability of 0.8 for Si, SiH and radicals and of 0.2 for radicals. A comparison between the experimental result and the simulation showed that the dominant radicals contributing to film growth are (x = 0 - 2). High-rate deposition of high-quality films in ECR plasma CVD demonstrates that the nature of the precursor species does not universally determine the film quality. Energetic particle bombardment permits high-quality films to be deposited despite the high reactivities of the precursor species.

SiO 2 coatings produced by ion beam assisted ECR-plasma CVD

Ion beam assisted electron cyclotron resonance plasma CVD (IB-PCVD) equipment was developed. Plasma was produced by a coaxial ECR discharge. A bucket-type ion source with a microwave plasma (MP) cathode was used as an ion source. Amorphous SiO 2 films were deposited on austenitic-type stainless steel and silicon wafer substrates by use of the IB-PCVD equipment. The effects of the gas flow of monosilane, carbon dioxide and hydrogen and oxygen ion energies have been studied in the relation to composition, structure, corrosion properties and oxidation protection potential of the films. The surface morphology was observed by scanning electron microscopy. Auger spectroscopy, X-ray photoelectron spectroscopy and Fourier transform IR were used to characterize films and interface. The corrosion protection potential in an aqueous environment was evaluated by electrochemical techniques. Oxidation behaviour in the atmosphere in an oven was studied at 1000 °C. Surfaces of the films were smooth, and grain structure was not clear. These films had good corrosion protection. Oxidation of steel substrate was suppressed by the SiO 2 coating. Oxygen irradiation during deposition was effective to improve corrosion and oxidation protection.

High Rate Deposition of Hydrogenated Amorphous Silicon Films by ECR Plasma CVD

AbstractA new electron cyclotron resonance (ECR) plasma CVD system has been developed in order to obtain high deposition rates. By using this system, hydrogenated amorphous silicon (a-Si:H) films have been prepared at a deposition rate of 1.0. μ m/min. The utilization efficiency of SiH4 gas is 16% under such conditions. Films prepared at 1.0 μ m/min have high photoconductivity (σ ph) of 10-6 S/cm and low dark conductivity (σ d) of 10-12 S/cm, leading to a high photosensitivity of σ ph/σ d=106. Both high microwave power and high SiH4 gas flow rates are essential to the high rate deposition of sufficiently photosensitive a-Si:H films. Annealing at 300° C improves the photosensitivity up to σ ph/σ d=107.

Properties of Hydrogenated Amorphous Silicon Prepared by ECR Plasma CVD Method

Hydrogenated amorphous silicon (a-Si:H) films were prepared by the microwave electron-cyclotron-resonance (ECR) plasma CVD method using SiH4 gas without intentional substrate heating. The influence of the deposition conditions in the ECR plasma CVD method on the properties of a-Si:H films was studied and the properties were correlated with plasma optical emission spectra of similar deposition conditions. Photoconductivity of ∼10-6 (Ω cm)-1 under simulated AM1 (100 mW/cm2) illumination was obtained for the as-grown film with an optical gap of ∼2.1 eV at the SiH4 gaspressure of 2×10-4 Torr. The photoconductivities, the optical gaps and the B values estimated from optical absorption measurements were widely changed when SiH4 gas pressure condition was changed. Infrared absorption spectra also showed that the Si-H2 stetching mode at ∼2100 cm-1 and (Si-H2)n wagging mode at ∼845 cm-1 increased as SiH4 gas pressure increased. Measurements of optical emission spectra in the SiH4 ECR plasma showed that the emission intensity ratio of Si (288 nm) to SiH (414 nm) was larger than that in conventional RF plasma CVD, and that the photoconductivities and optical gaps increased as this ratio increased.

Highly conductive p-type microcrystalline SiC:H prepared by ECR plasma CVD

Highly conductive p-type microcrystalline SiC:H films have been prepared by ECR (electron cyclotron resonance) plasma CVD. The material with an optical energy gap of 2.25 eV exhibits a dark conductivity as high as 10 S cm -1 which is more than seven orders of magnitude higher than that of amorphous SiC:H prepared by conventional RF plasma CVD. The optimal energy gap can be controlled in the range from 2.0 to 2.8 eV, while retaining excellent conductivity. Utilizing this material as a wide-gap heterojunction contact in amorphous silicon solar cell, a conversion efficiency of 12.0% has been obtained with a large open circuit voltage.

Effects of Deposition Method on the Properties of Silicon Nitride and Silicon Oxynitride Films

The compositional properties of silicon nitride (SiN) and silicon oxynitride (SiON) films prepared by electron cyclotron resonance plasma CVD (ECR P-CVD) and conventional plasma CVD (P-CVD) methods have been investigated and compared. SiH4-N2 gas was used for SiN depositions in both methods. O2 gas and N2O gas were added to SiH4-N2 gas for SiON film formations in ECR and P-CVD depositions, respectively. SiN films with the N/Si ratio in excess of a stoichiometric value and predominantly with N-H bonds are more easily obtained by the ECR P-CVD method than by the P-CVD method. Hydrogen concentrations were found to be nearly the same in the SiN films deposited by both methods in the microwave powers and rf power of 150-500 W. The addition of O2 and N2O gases to the SiH4-N2 resulted in an increase in the deposition rates of SiON films of about 1.5 times that of SiN films. A slight addition of O2 and N2O gases resulted in a decrease in the absorption due to Si-H bonds and an increase in the absorption due to N-H bonds. Additions of more than a certain amount of O2 or N2O gases resulted in the disappearance of Si-H and N-H bonds. However, hydrogen atoms were found to be still contained in SiON films, although the concentration is a little low in comparison with those in SiN films. The excited states of oxygen are considered to have great influence on such film compositions.

Annealing behavior of silicon nitride and silicon oxynitride films prepared by ECR plasma CVD method

The influence of thermal annealing on the bond configuration and structural properties of silicon nitride (SiN) and silicon oxynitride (SiON) films prepared by the electron cyclotron resonance plasma CVD (ECR p-CVD) method have been studied. Both the SiN and SiON films deposited at high microwave powers in which the N-H bonds are predominant have been found to be thermally stable even after annealing at 900°C from results of IR absorption measurements. The ESR measurements for the SiN films revealed that the spin densities of the films deposited at high microwave powers also showed no change at high annealing temperature, while those of the films prepared at a low microwave powers change at an annealing temperature of 400°C.

Visible light thin film LED made of a-SiC p-i-n junction

A visible-light injection-type electroluminescence thin film diode made of amorphous silicon carbide p-i-n junction (a-SiC TFLED) has been developed. The emission color can be controlled from red to yellow by adjusting the optical energy gaps of the luminescent i-layer and the carrier injector p-layer. A brightness of 10 cd/m 2 has been obtained in a yellow emission LED at an injection current density of 100 mA/cm 2 and a forward bias of 10 V. A series of technical data on the device fabrication technology is presented. As a result, an improvement of carrier injection efficiency by utilizing wide-gap p- and n-a-SiC prepared by ECR (electron cyclotron resonance) plasma CVD as well as a possibility of the application of a-SiC TFLED to OE-IC are demonstrated and discussed.

Silicon Nitride Passivant for HgCdTe n+p Diodes

A film deposited by electron cyclotron resonance plasma CVD has been successfully applied as a surface passivant for n+p diodes. The ECR‐plasma CVD assures low temperature deposition of film on . The has an excellent interface with with a surface‐state density as low as and a low fixed charge of . Measurement of flatband shifts after exposure to humidity verify that the is more moisture resistant than the conventional passivant. A diode passivated with had a zero bias resistance of at 77 K.