Resonance Plasma Chemical Vapor Deposition Research Articles

The characteristics before and after annealing of amorphous silicon films prepared by ECR plasma CVD

The optical and electrical properties before and after annealing of amorphous silicon films, deposited by electron cyclotron resonance plasma chemical vapor deposition as a function of substrate temperature, were investigated. The properties of non-annealed Si films were improved with increasing substrate temperature. On the other hand, Hall mobility of annealed Si films decreased with increasing substrate temperature.

Characteristics of a-si:h films prepared by ecr cvd as a function of the h 2/sih 4

The optical, electrical and structural properties of hydrogenated amorphous silicon films were investigated as a function of the H 2/SiH 4 ratio. The films were deposited by electron cyclotron resonance plasma chemical vapor deposition method in the source gas limited and electron flux limited mode. In the source gas limited mode, the properties of amorphous silicon films were improved with increasing deposition rate photoconductivity, hydrogen content increased and optical band gap, full width at half maximum of the Raman spectroscopy and the ratio of the concentration of dihydride to that of monohydride decreased. In the electron flux limited mode, the optical, electrical and structural properties as well as the deposition rate did not improved any more. The photoconductivity was over 10 −5 Ω −1 cm −1 when the optical band gap was 1.75 ~ 1.77 eV, FWHM was below 75 cm −1, hydrogen content was about 21 at.% and the ratio of dihydride to the monohydride was about 1.5 in the electron flux limited mode.

Dielectric properties of silicon nitride films deposited by microwave electron cyclotron resonance plasma chemical vapor deposition at low temperature

The dielectric properties of amorphous silicon nitride (SiNx) films that were prepared by microwave electron cyclotron resonance plasma chemical vapor deposition at low temperature in the frequency range 5 Hz–1 MHz have been investigated. The dielectric dispersion in the frequency range exhibits two fractional power laws of (ε′−ε∞′)∝ω−p1 and (ε′−ε∞′)∝ωn1−1 with p1=0.12–0.18 and n1=0.95–0.96. These are close to the result predicted by the many-cluster anomalous conduction theory of fractal structure.

Fractal Aggregation Behavior in Amorphous Silicon Nitride Films

A fractal aggregation behavior in amorphous silicon nitride (SixNy) films deposited by microwave electron cyclotron resonance plasma chemical vapor deposition is reported. The fractal structure and dimension of 1.45 obtained by experiment and computer simulation are all in excellent agreement with the result predicted by the cluster-cluster-aggregation model. The forming of fractal structure is related to the change of discharge mode between ring plasma and bulk plasma.

Boron doping effects and microcrystallite formation in SiC:H films prepared using ECR-CVD

Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance plasma chemical vapour deposition (ECR-CVD) method from a mixture of methane, silane and hydrogen, with diborane as the doping gas. The tubular vessel used had a substrate receiver circular area of 87cm 2 and was fitted with magnetic coils to guide the microwave power into the deposition section. The effect of changes in the diborane fraction on the deposition rate, optical bandgap, and electrical conductivity and its activation energy were investigated. Raman scattering analysis showed that films deposited at a low microwave power of 150 W (2.45 GHz) were largely amorphous and the bandgap decreased as the diborane fraction was increased, but films deposited at 800 W and low diborane fractions were highly conductive and contained microcrystalline silicon inclusions. The films became amorphous as the diborane fraction was increased, while the optical bandgap remained relatively unchanged throughout the diborane fraction range. The activation energy varied in an opposite manner to the change in the electrical conductivity.

Some effects of boron doping in a-SiC:H films prepared by the ECR-CVD method

Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance plasma chemical vapour deposition (ECR-CVD) method from a mixture of methane, silane and hydrogen, with diborane as the doping gas. The effect of changes in the percentage of the diborane to reactant gas mixture on the deposition rate, optical bandgap and photoconductivity were investigated. There is evidence from Raman scattering analysis to show that films deposited at a low microwave power of 150 W were all amorphous and the bandgap decreased as the diborane fraction increased whereas films deposited at a high microwave power of 800 W at low diborane fractions are photoconductive and contain microcrystalline silicon inclusions. These films became amorphous as the diborane fraction was increased, while the optical bandgap remains relatively unaffected throughout the entire range of diborane fractions investigated.

Metallization of Polymers Using Plasma‐Enhanced Chemical Vapor Deposited Titanium Nitride as Interlayer

A low‐temperature process for titanium nitride (TiN) deposition by means of an electron cyclotron resonance plasma chemical vapor deposition process was applied to poly(tetrafluoroethylene), polyimide, benzocyclobutene, and poly(butyleneterephthalate). The organometallic compounds tetrakis(dimethylamido)titanium or titanium(IV)isopropoxide introduced into the downstream region of a nitrogen electron cyclotron resonance plasma were used as precursors for TiN deposition at 100°C. The thin TiN film (thickness 15 to 30 nm) acts as a conductive interlayer for the electroplating process or as adhesion promoter for sputtered titanium films. Prior to the deposition of the interlayer, the samples were treated on a biased susceptor with argon ions to enhance the adhesion of the TiN interlayer. This metallization procedure avoids the use of toxic and pollutive etching agents for polymer activation as well as a electroless metal deposition. The maximum adhesion of the electroplated copper on poly(tetrafluoroethylene) and poly(butyleneterephthalate) was established to be 13 and , respectively. For sputtered Ti films on polyimide and benzocyclobutene, maximum adhesion was 16 and , respectively. As shown by atomic force microscopy, TiN grains were formed on the polymer surface. Film composition was investigated by secondary ion mass spectrometry.

DIELECTRIC PROPERTIES OF SiNx FILMS DEPOSITED AT LOW TEMPERATURE

The dielectric properties of SiNx films,which were deposited at low temperature by microwave electron cyclotron resonance plasma chemical vapor deposition,have been investigated.The frequency dependence of ε′and ε″ have two kinds of power-law dependence in the frequency range of 5—106Hz due to the fractal structure in nanometer-sized amorphous films.The relationship between ε′and ωn－11 with n1=0.82—0.88- due to electron hopping are obtained at low frequency region,and the relationship between ε′ and- ωn－12 with n2=0.05 due to the fractal structure conduction are- obtained at high frequency region.

Influence of boron doping on the properties of amorphous and microcrystalline SiC films prepared using ECR-CVD

Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance plasma chemical vapor deposition (ECR-CVD) method from a mixture of methane, silane, and hydrogen, with diborane as the doping gas. The effect of changes in the percentage of the diborane to reactant gas mixture on the deposition rate, optical bandgap, and photoconductivity were investigated. There is evidence from Raman scattering analysis to show that films deposited at a low microwave power of 150 W were all amorphous and the bandgap decreases as the diborane level is increased whereas films deposited at a high microwave power of 800 W at low diborane levels are highly photoconductive and contain microcrystalline silicon inclusions. These films become amorphous as the diborane level is increased, while the optical bandgap remains relatively unaffected throughout the entire range of diborane levels investigated. The effect of the microwave power was also investigated. The conductivity increases rapidly to a maximum, followed by rapid reduction at high microwave powers. Raman scattering analysis showed evidence of the formation and increase of microcrystalline silicon inclusions and diamond-like components in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity.

Effect of fluorine on dielectric properties of SiOF films

The effect of fluorine addition on silicon oxide film properties as a function of SiF4/O2 gas flow ratio was investigated. The films were deposited by using electron cyclotron resonance plasma chemical vapor deposition with SiF4 and O2 as source gases diluted in Ar. Characterization of films was carried out in terms of various gas flow ratios (SiF4/O2=0.2–1.0). The microwave power and substrate temperature during deposition were fixed at 700 W and 300 °C, respectively. The chemical bonding structure of the films was evaluated by Fourier transform infrared spectroscopy (FTIR), fluorine concentration by x-ray photoelectron spectroscopy, and refractive index by ellipsometry. The dielectric constant was determined from C–V measurements at 1 MHz. FTIR spectra show that as the fluorine concentration increased, the intensities of the Si–F bonding peak and the shoulder peak (at around 1160 cm−1) of the Si–O stretching mode both increased. Refractive index and deposited film density decreased with increasing SiF4/O2 gas flow ratio. The SiOF film deposited at a SiF4/O2 gas flow ratio of 1.0 exhibited a fluorine content of 11.8 at. % and a dielectric constant of 3.14.

Low Temperature Deposition of (Ba, Sr)TiO3 Films by Electron Cyclotron Resonance Plasma Chemical Vapor Deposition

(Ba, Sr)TiO3 films deposited by electron cyclotron resonance plasma chemical vapor deposition at 450° C and 500° C are investigated. The crystallinity, evaluated by X-ray diffraction and by measuring grain size, and electrical properties of films were evaluated for changes in deposition temperature, deposition rate, and Ba content, without a post-deposition annealing. Slower deposition rates as well as higher deposition temperatures were found to improve film crystallinity. Evaluation of electrical properties and film crystallinity revealed that the optimum Ba content of a film deposited at 500° C was 0.4. A 27 nm thick film deposited on a Pt substrate at 500° C and at 1.1 nm/min with a Ba content of 0.4 exhibited a SiO2 equivalent thickness of 0.65 nm and a leakage current density of 4.6×10-7 A/cm2 at 1 V. The film composition was found to be sufficiently uniform throughout, i.e., from the top to the side of the films on a stacked bottom electrode.

SiCN alloys deposited by electron cyclotron resonance plasma chemical vapor deposition

Silicon–carbon–nitrogen alloys have been deposited by electron cyclotron resonance plasma chemical vapor deposition. Nitrogen, methane, and argon diluted silane have been used as precursor gases. The properties of the deposited films were studied by spectroscopic ellipsometry, Fourier transform infrared spectroscopy, X-ray photoelectron, and Auger electron spectroscopy. The structure and bond formation in the SiCN films is discussed in terms of the present results.

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.

New method for in situ control of Bragg reflector fabrication

A simple, robust method for real time monitoring of Bragg reflector layer thickness is described. The method is based on the choice of the appropriate ellipsometric measurement wavelength to control the deposition of the top layer. This method requires no information on the underlying structure. To evaluate the method, Bragg reflectors were developed with SiO2 and SiNx stacks grown by electron cyclotron resonance plasma chemical vapor deposition. Reflectivity measurements performed on these reflectors confirm the reproducibility and accuracy of the method.

Low Temperature Fabrication of (Ba, Sr)TiO3 Thin Films by ECR Plasma CVD

AbstractPhysical and electrical properties are investigated for (Ba, Sr)TiO3 (BST) films prepared by electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) at relatively low temperatures, between 450 °C and 500 °C. The crystallinity of BST, estimated by X-ray diffraction and from the grain size, is greatly improved when the temperature is raised from 450 °C to 500 °C. Also better crystallinity is obtained for films grown at a deposition rate of 1.1 nn/min than at 2.7 nm/min. The mass transport rates of metal organic sources under our deposition conditions are estimated. The BST film composition is precisely controlled using the results of the investigation on mass transport. At near stoichiometric composition, i.e., (Ba+Sr)/Ti=0.97, and Ba/(Ba+Sr)=0.4, the films grown at 500 °C are found to have the largest dielectric constant, measured using flat capacitors with Pt bottom electrodes. A dielectric constant of 160 is obtained for 27 nm thick films grown at 500 °C and at 1.1 nm/min, without post-deposition annealing. These films exhibit the smallest SiO2 equivalent thickness of 0.65 nm and a leakage current density of 4.6x10−7 A/cm2 at plus IV.

Radical Fluxes in Electron Cyclotron Resonance Plasma Chemical Vapor Deposition of Amorphous Silicon

The precursors of a-Si:H films in electron cyclotron resonance plasma chemical vapor deposition have been investigated by analyzing the deposition profile on a trench. The profile of the film prepared from radicals produced in the gas phase by electron collision with SiH4 is simulated by a Monte Carlo method using a sticking probability of 0.8 for Si, SiH and SiH2 radicals and of 0.1 for SiH3 radicals. A comparison between the experimental result and the simulation has shown that the ratio of the total flux of SiHx (x=0-2) to the flux of SiH3 in the radicals reaching the surface is 0.82 at 3 mTorr. The flux of radicals which maintain the momentum of SiH4 emitted from a nozzle is also compared with that of radicals with a random direction of momentum.

A study of silicon epitaxial growth on silicon substrates exposed to Ar electron cyclotron resonance plasmas

Epitaxial growth of Si on Si(100) wafers was carried out at 700 °C in an Ar microwave electron cyclotron resonance plasma chemical vapor deposition system. Both plasma exposure prior to growth and epitaxial growth were monitored by real‐time single‐wavelength ellipsometry, first to determine an optimum end point for Ar plasma cleaning which would favor quality epitaxial growth, and second to follow the growth of the epitaxial film. Spectroscopic ellipsometry combined with cross‐sectional transmission electron microscopy and atomic force microscopy were used to characterize the epitaxial films, the epitaxial film/substrate interface, and the surface morphology. Secondary‐ion mass spectroscopy was used to evaluate the contamination levels at the film/substrate interface. Epitaxial films were successfully grown on both, smooth and rough (20–30 nm roughness layer) Si substrates. For both cases the top surface of the epitaxial film was smooth, but the interfaces were different.

Ellipsometry study of the nucleation of Si epitaxy by electron cyclotron resonance plasma chemical vapor deposition

The formation and evolution of Si nuclei on the Si(100) surface at 600 and 700 °C were observed in a microwave electron cyclotron resonance plasma chemical vapor deposition system, using both real-time in situ single wavelength and spectroscopic ellipsometry combined with high-resolution cross-sectional transmission electron microscopy and secondary ion mass spectroscopy. The deposited Si layers are epitaxial, and decidedly different nucleation behavior is seen at 600 and 700 °C. The experimental ellipsometry results were compared with simulations and the results show that temperature has a profound effect on the initial nucleation and growth, and the different interface structures that are observed are attributable to impurities.

Void formation at silicon nitride/silicon interfaces studied by variable‐energy positrons

AbstractVariable‐energy positrons (VEP) were used to study the deppth distribution of defects in SiNx/Si structures fabricated using ditertiary butyl silane (CONSI 4000) as the silicon precursor in an electron cyclotron resonance plasma chemical vapour deposition system. Films were grown to thicknesses ranging from 500 to 3500 Å at substrate temperatures between room temperature and 400°C and under various plasma conditions. The VEP results give evidence for differing concentrations of very large open‐volume defects at several of the SiNx/Si interfaces, confirmed by transmission and scanning electron microscopy. Their presence was correlated with non‐reactive organosilicon adsorption on the substrates prior to the thin film deposition.

Ultrahigh-Vacuum Electron Cyclotron Resonance-Plasma Chemical-Vapor-Deposited SiNx Films for X-Ray Lithography Mask Membrane: As-Deposited Properties and Radiation Stability

In this paper, a new approach to improve the radiation stability of silicon nitride film is presented using an ultrahigh-vacuum electron cyclotron resonance plasma chemical vapor deposition system. A membrane with a high optical transmittance (∼99% at 633 nm) can be obtained with a lower SiH4/NH3 flow ratio. The X-ray radiation immunity, however, can be improved with a higher SiH4/NH3 flow ratio at the sacrifice of optical transmittance. Shrinkage of the band gap and the generation of energy states in the band gap with increasing Si/N ratio of the film are speculated to be primary parameters for improving the radiation stability of silicon nitride film. Hydrogen content in the low 1021 atom/cm3 range, however, does not seem to have a critical effect on the radiation immunity, even though the Si-H bonds may act as the source for the radiation-induced damage.