Electron Cyclotron Resonance Microwave Research Articles

Electron temperature measurement in a slot antenna 2.45 GHz microwave plasma source

The electron temperature in a low-pressure microwave electron cyclotron resonance slot antenna produced plasma is obtained. The upper excited atomic level populations have been measured through atomic emission spectroscopy. It has been shown that the Corona balance provides a good description of such levels and, based on this fact, a simple argon collisional-radiative model has been used in the temperature determination.

Characteristics of a large diameter reactive ion beam generated by an electron cyclotron resonance microwave plasma source

A new ion source with a large beam diameter generated by an electron cyclotron resonance microwave plasma source is presented. Ion beams with a beam diameter of >160 mm and a maximum argon-ion current density of 2.1 mA/cm2 are obtained. For this large two-electrode silicon-ion extraction optics are mounted into an electron cyclotron resonance microwave plasma source. With ion extraction optics installed an electron temperature up to three times higher than without optics was observed. Due to this high electron temperature (up to 12 eV) the O+ concentration as compared to the O2+ concentration is enhanced in an oxygen plasma. Therefore, a very reactive oxygen ion beam with an ion current density of 1.1 mA/cm2 can be generated. Ion energies of 1 keV corresponding to the screen grid voltage are obtained with a small energy spread of 10 eV full width at half maximum or less. The low working pressure (about 10−4 mbar) is well suited for low-pressure ion-beam processes.

OPTICAL PROPERTIES OF AMORPHOUS FLUORINATED CARBON FILMS PREPARED BY ELECTRON CYCLOTRON RESONANCE PLASMA

The optical property of amorphous fluorinated carbon (α-C∶F) films are investigated, which are prepared by microwave electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) using trifluromethane (CHF3) and benzene (C6H6) as source gases. The optical energy gap Eg of the α-C∶F films deposited at 140—700W powers and CHF3∶C6H6=1∶1—10∶1 are between 1.76 and 2.85eV. The amount of fluorine in the films has an effect on optical absorption and energy gap. The absorption edge increases as the amount of fluorine is raised. The optical energy gap Eg is mainly determined by CF bond in the films, which results in the change of the density of states in band tail of the valence band.

Growth of Gallium Nitride Textured Films and Nanowires on Polycrystalline Substrates at sub-Atmospheric Pressures

AbstractTextured gallium nitride (GaN) films were grown on polished, polycrystalline and amorphous substrates in sub-atmospheric pressures, by direct nitradation of a thin molten gallium films using electron cyclotron resonance (ECR) microwave nitrogen plasma. C-plane texturing was achieved, independent of the substrate crystallinity. Single crystal quality GaN nanowires with diameters ranging from 40-50 nm were also synthesized using direct nitridation of thin gallium films with nitrogen plasma. Scanning electron microscopy (SEM), X-ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and Cross-sectional transmission electron microscopy (CS-TEM), high-resolution TEM (HRTEM) and Micro-Raman spectroscopy were used to characterize the synthesized gallium nitride films and GaN nanowires.

CVD Diamond Coating on WC Cutting Tool Using Electrophoresis.

CVD diamond films were deposited on commercial WC cutting tools. An electron cyclotron resonance microwave plasma chemical vapor deposition (ECR-MPCVD) apparatus was used to deposit diamond films. Methane and hydrogen were used as gaseous source for CVD, and WC-Co (JIS standard: K-10) was used as a substrate for CVD. Cobalt on the surface of the WC cutting tool prevented CVD diamond from depositing on the WC cutting tool. Scratching with diamond particles on the surface of the WC cutting tool, which is one of the most popular pretreatments for enhancing the nuclei density of CVD diamond, was ineffective on the WC cutting tool without removing surface cobalt. On the other hand, Electrophoresis treatment was effective for increasing diamond nuclei density on the WC cutting tool without removing surface cobalt. However, CVD diamond films synthesized on the WC cutting tool (from which surface cobalt was removed) using electrophoresis pretreatment separated from the surface of the WC cutting tool. To improve the adhesion between CVD diamond film and WC cutting tool, heat treatment was performed after electrophoresis pretreatment. The heat treatment condition was 500°C for 1h in Ar flow. The heat treatment after electrophoresis treatment was effective for improving adhesion between WC surface and CVD diamond film. Vickers hardness test was carried out for estimating the adhesion. The Vickers hardness of the CVD diamond film obtained by the electrophoresis-heat pretreatment, was as hard as that of a CVD diamond film obtained with conventional scratching pretreatment. From the results of Vickers hardness test, it was found that heat treatment after electrophoresis process is effective for improving the strength of the adhesion layer.

Preparation of AlN films by pulsed laser deposition using sintered aluminum nitride and elemental aluminum as raw materials

Aluminum nitride films have been prepared on Si (100) substrates through two methods: basic pulsed laser deposition from sintered aluminum nitride ceramics and plasma-aided reactive pulsed laser deposition from elemental aluminum metal. The latter was performed in a nitrogen plasma environment generated from electron cyclotron resonance microwave discharge. The films deposited by both methods have been characterized by various techniques to examine the morphology and to determine the composition and structure. The formation of aluminum nitride compound was confirmed in the deposited films. The films prepared by basic pulsed laser deposition are found to contain oxygen impurities, while those obtained through the plasma aided method have exhibited a stoichiometric AlN composition. The films have shown better crystalline quality when prepared at higher temperatures, however, when aided by the nitrogen plasma the films contain pure AlN compound with much better crystalline quality even prepared at low temperatures. Mechanisms relevant to the deposition processes are also discussed with particular emphasis on the contributions of the nitrogen plasma to the film formation. A comparison of the different characteristic features associated with the films prepared by the two methods shows that the plasma aided method has reasonable advantages in preparing compound films.

磁性材料 有機可塑基板上に堆積させたＣｏ含有酸化鉄薄膜

Co-containing ferrite thin films were successfully deposited on organic flexible substrates by the reactive sputtering method using-an electron cyclotron resonance microwave plasma at a temperature lower than 150°C. The ferrite thin films had an amorphous-like structure, perpendicular magnetic anisotropy and high perpendicular coercivity of about 170kA/m. The perpendicular coercivity increased with increasing substrate thickness. Inserting SiO2 underlayer between organic flexible substrate and ferrite thin films enhanced the perpendicular coercivity.

Fracture resistance enhancement of diamond-like carbon/nitrogenated diamond-like carbon multilayer deposited by electron cyclotron resonance microwave plasma chemical vapor deposition

Diamond-like carbon (DLC), nitrogenated diamond-like carbon (CNx) and multilayered DLC/CNx films of 350 nm overall thickness were deposited on Si (100) substrates by using an electron cyclotron resonance microwave plasma chemical vapor deposition system. The deposited films were investigated for the fracture resistance using nanoindentation and nanoscratch methods in combination with scanning electron microscopy. In nanoindentation fracture tests, the film fracture was detected by the discontinuities in the load-displacement curves. The abrupt increase in the friction force between the tip and films during nanoscratch fracture tests was taken as a criterion for film fracture. Both the nanoindentation and nanoscratch fracture tests revealed that the DLC/CNx multilayer exhibited substantially higher critical load than that measured for either DLC or CNx films, though there was no obvious enhancement in the multilayer hardness and elastic modulus while the multilayer internal stress was between that of DLC and CNx. This study suggests that the fracture resistance of hard coatings can be improved by the design of a suitable multilayer structure.

Some growth peculiarities of a-C:H films in ECR microwave plasma

The chemical vapor deposition (CVD) process of a-C:H films from methane and argon gas mixtures in an electron cyclotron resonance (ECR) microwave plasma has been studied. The formation of a-C:H films in a wide range of basic parameters has been investigated. The basic parameters are the following: the total pressure of the working gas mixture, the composition of the gas mixture, the magnitude of microwave power absorbed in a plasma, the location of the substrate L ECR-S with respect to the position of ECR and substrate material (Si, ceramic). We found that extremely low or zero growth rate of the a-C:H films takes place in the cases when (i) the substrate is placed in the ECR plane or its close vicinity and (ii) a high microwave power is used; the latter situation occurs when the power is about 300 W or greater. The increase in deposition rate takes place under the increase of the L ECR-S distance or under the decrease of the microwave power. The deposition rate of a-C:H films on the ceramic substrate was higher than that on the silicon substrate for all values of operating pressure. These peculiarities are explained in terms of additional heating of Si substrates by microwave power absorption outside the ECR region. A later (latent) parameter should be taken into account in the analysis of the deposition process and choice of the substrate material. The mechanism leading to a very high growth rate of a-C:H polymer-like films is discussed.

Relative Irradiance Measurement and Bonding Configurations of Amorphous Fluorinated Carbon Films Deposited by Electron Cyclotron Resonance Plasma

α-C:F films are deposited by microwave electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of α-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that α-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.

Visible photoluminescence and electroluminescence in wide-bandgap hydrogenated amorphous silicon

Abstract The work describes basic photoluminescence (PL) and electroluminescence (EL) properties of wide-bandgap (2.0 eV or greater) hydrogenated amorphous silicon (a-Si: H). Thin films of wide-bandgap (high-hydrogen-content) a-Si: H were prepared by microwave electron cyclotron resonance plasma-enhanced chemical vapour deposition from SiH4 under high dilution with He. The films exhibit spectrally broad (full width at half-maximum, 0.4 eV or greater) visible PL at room temperature, peaked at about 1.5eV. On the basis of measurements of the PL temperature dependence, PL dynamics, infrared absorption spectra, picosecond pump-and-probe experiments and hydrogen thermal desorption spectroscopy the dominant microscopic mechanism of visible PL has been revealed to be the radiative de-excitation of oligosilane (-(SiH2)2-) units or of a specific defect in their close vicinity. EL has been investigated in sandwich p+[sbnd]i[sbnd]n+ and p+[sbnd]p[sbnd]n[sbnd]n+ structures with (Cr[sbnd]Ni)/indium tin oxide contacts....

Plasma-based low-energy ion implantation for low-temperature surface engineering

This paper summarizes the plasma-based low-energy ion implantation technique, including plasma source ion nitriding/carburizing and plasma source low-energy ion enhanced deposition of thin films, developed from a combination of two techniques based on conventional plasma-based ion implantation and low-energy ion beam implantation for improvement in wear resistance and corrosion resistance for metals and alloys. An electron cyclotron resonance (ECR) microwave plasma source is used to produce the plasma with the high plasma density, electron temperature and ionization degree. The ions are accelerated from the plasma by a low pulsed negative bias of −0.4–−3 kV, which is similar to the cathode potential of conventional plasma thermo-chemical diffusion processing. The low process temperature is in the range from 150°C to 500°C, which corresponds to the upper limit of conventional ion beam implantation and to the lower limit of plasma thermo-chemical diffusion processing, respectively. Low-energy ion implantation and simultaneous indiffusion is the main mass transfer mechanism, and direct thermo-chemical diffusion absorption is an additional mass transfer mechanism for formation of the nitrided/carburized layer and thin film. It has been proved that plasma-based low-energy ion implantation technique has the potential for applications in industry for surface modification of metals and alloys.

Physical properties of a-C:H films prepared by electron cyclotron resonance microwave plasma chemical vapor deposition

a-C:H films have been deposited on silicon and glass using electron cyclotron resonance microwave plasma decomposition of CH 4 diluted with Ar gas at 0–160 V rf negative bias and 65–250 W microwave power. The deposition rates, absorption coefficients, optical bandgaps, refractive indices and internal stresses of the a-C:H films grown under varying preparation parameters have been measured. The microstructure of the carbon films has been evaluated by Raman spectroscopy. It has been found that the properties and structure of the carbon films are strongly dependent upon the rf substrate bias voltage. At lower rf biases (0 and 40 V), the films are transparent polymer-like carbon films with lower refractive indices, lower internal stresses, and higher optical bandgaps; at higher rf biases (80, 120 and 160 V), they are semi-transparent diamond-like carbon films with higher refractive indices, higher internal stresses and lower optical bandgaps. Microwave power has little influence on the properties and structure of the a-C:H films.

A New Method for Thin Film Deposition—Faced Microwave Electron Cyclotron Resonance Plasma Sources Enhanced Direct-Current Magnetron Sputtering

A new reactive magnetron sputtering system enhanced by the faced microwave electron cyclotron resonance plasma source was designed and amorphous CNx films has been prepared by using this system. The characterization of the films by interference microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy shows that the deposition rate is strongly affected by the direct-current bias, and the films are composed by a single carbon nitride phase and the N/C ratio is 4:3.2, which is close to that of C3N4 (4:3).

In situ Fourier transform P-polarized infrared reflection absorption spectroscopic investigation of an interface properties of SiO 2/Si(100) deposited using electron cyclotron resonance microwave plasma at room temperature

Amorphous SiO 2 films have been deposited onto the Si substrate, without heating, using sputtering-type electron cyclotron resonance (ECR) microwave plasma. In situ Fourier transform P-polarized infrared reflection absorption spectroscopy (ISFT-PIRRAS) has been used to study the properties of a-SiO 2/Si interface. The results from ISFT-PIRRAS monitoring indicated that the interface stress led to significant distortion in the local structure, which resulted in the broadening of a transverse optical mode (TO 3) located at 1050 cm −1. The interface stress decreased with increased film thickness. In addition, the longitudinal optical phonon mode (LO 3, located at 1223 cm −1) related to TO 3 mode was observed due to Berreman effect [B. Harbecke, Appl. Phys. A: Solids Surf. 38 (1985) 263]. This phonon mode is very sensitive to SiO 2 film thickness, which enables it to be used to detect and characterize ultra thin SiO 2 film. When the film thickness is over 30 nm, a non-linear dependence of the intensity of LO 3 mode on film thickness was observed. However, the TO 3 mode has a near linear dependence on film thickness. Thus, it is more accurate and suitable to detect thick film by monitoring TO 3 mode intensity.

Plasma source low-energy ion-enhanced deposition of thin films

Plasma source low-energy ion-enhanced deposition is a new approach for the deposition of thin films on steel and alloys with specific advantages over ion beam-enhanced deposition (IBED) and the complex combined plasma source ion implantation (PSII) and IBED (PSII-IBED). It may be used to develop a thin film process using the plasma-based low-energy ion implantation including plasma source ion nitriding and plasma source ion carburizing. A deposition apparatus based on an electron cyclotron resonance (ECR) microwave plasma source, a magnetron sputtering target and a pulsed low-voltage power supply from 0.5 to 2 kV has been developed. The magnetron sputter deposition of Ti metal films and plasma source low-energy nitrogen ion implantation under a high nitrogen ion implantation dose rate of 0.65–1.20 mA/cm 2 are used alternately in order to synthesize the stoichiometric TiN films on A3 mild steel and M2 high-speed steel at a deposition rate of 50–110 nm/min. The Knoop microhardness of the 1.2–1.6 μm thick TiN films on the M2 steel is in the range of 18.0–20.0 GPa (0.05 N load). The critical loads of the TiN films on the M2 steel measured by the scratch test are 22–35 N corresponding to the formation of an intermixed layer of about 40 nm thick between the film and the steel substrate. The corrosion resistance of the TiN films in 0.5 mol/l H 2SO 4 solution is evaluated by performing electrochemical polarization measurements. Their superior corrosion resistance is a result of the dense fine-grained microstructure and is independent of the preferential orientation of the films.

Light emitting wide band gap a-Si:H deposited by microwave electron cyclotron resonance plasma-enhanced chemical vapour deposition

We investigate hydrogenated amorphous silicon (a-Si:H) from the point of view of light emitting applications. Thin films of wide band gap a-Si:H were prepared from silane SiH 4 diluted with He by using the microwave electron cyclotron resonance plasma enhanced chemical vapour deposition. Room temperature photoluminescence (PL) and mainly electroluminescence (EL) of p +–i–n + (p +–p–n–n +) structures were studied. The PL and EL emission spectra are in the red/near-infrared region. EL, occuring in fact in recrystallised parts of the devices (the crystallisation arising as a result of the application of an external bias), has hysteresis and the EL devices evoke the a-Si:H memory switches.

Unstable plasma characteristics in mirror field electron cyclotron resonance microwave ion source

Electron cyclotron plasma reactor are prone to instabilities in specific input power [3–7] region (150–450 watts). In this region power absorption by gas molecules in the cavity is very poor and enhanced input power gets reflected substantially without increasing ion density. There are abrupt changes in plasma characteristics when input power was decreased from maximum to minimum, it was observed that reflected power changed from <2% to ∼50%. Minimum two jumps in reflected power were noticed in this specific power region and these appear to be highly sensitive to three stub tuner position in the waveguide for this particular input power zone. Unstable plasma region of this source is found to be dependent upon the magnetic field strength. Some changes in reflected power are also noticed with pressure, flow and bias and they are random in nature.

Preparation and Analysis of Si3N4 Film

Microwave Electron Cyclotron Resonance (ECR) Plasma assisted Chemical Vapor Deposition (CVD) technology has been used to prepare Si3N4 films, which were analyzed by using infrared (IR) transmission spectroscopy and XPS. The analysis results show that with the increase of the deposition temperature, the H content decreases, and the densification of the film increases. When the temperature is up to 360 °C, the stoichiometrical rate of Si:N is close to 0.75. The protective property of Si3N4 films is also examined.

Hydrogenated amorphous carbon films deposited in an electron cyclotron resonance–chemical vapor deposition discharge reactor using acetylene

Hydrogenated amorphous carbon (a-C:H) films have been deposited from acetylene gas in a microwave electron cyclotron resonance (ECR) plasma reactor. The films were deposited at a pressure of 0.2 mTorr and at radio frequency (r.f.) induced substrate biases from 80–300 V. Selected film properties, including optical bandgap and bonded hydrogen content, were measured. At r.f. induced biases from 150 to 300 V, corresponding to ion energies for C 2 H 2 + of approximately 150–300 eV, the hydrogen content remains constant and the optical bandgap peaks at a bias of 200 V, or approximately 100 eV per carbon in the C 2 H 2 + ions. This ECR system result is in agreement with those observed by other researchers using different deposition methods where an optical bandgap maximum and an sp 3 maximum occurs at ion energies of 90–100 eV per carbon atom. The discharge properties measured include a partial pressure analysis of the residual exit gas and the substrate current density.