Effect of oxygen to argon ratio on the properties of thin SiO x films deposited by r.f. sputtering (original) (raw)
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The influence of O2 flow rate on the compositional, optical and electrical characteristics of silicon oxide (SiOx) thin films (x < 2) were studied in this work. The SiOx thin films were obtained by pulsed direct current (DC) magnetron sputtering (PMS) onto n-type Si wafers (and also on glass substrates) at a vacuum of 3 × 10−3 Pa. Rutherford backscattering spectrometry (RBS) was used to check the compositional elements of deposited films and its oxidized states were analysed via Fourier-transform infrared (FTIR) spectroscopy. The optical properties of as-deposited SiOx thin films were investigated from transmittance measurements at room temperature in the wavelength range of 250–800 nm. The obtained data reveal that the Urbach energy (a measure of the band tail extension, Eu) decreased from about 523 to 172 meV as the rate of oxygen gas flow increased. On the contrary, the optical energy band-gap (Eg) increased from 3.9 to 4.2 eV. Conduction and valance band positions (relative t...
Semiconductor Science and Technology, 2009
We report the effects of varying the oxygen partial pressure (OPP) on the structural and electronic properties of SiO x /Si heterolayers grown by RF reactive sputtering. The produced samples present silicon poly-crystalline characteristics for low values of OPP. The crystallinity decreases as the OPP increases due to oxygen interdiffusion until the silicon crystal structure becomes amorphous. The results of infrared and Raman spectroscopies show higher deviation from stoichiometry and an increment of structural disorder for samples grown with higher values of OPP. Room temperature photoluminescence (PL) is present in all as-grown samples. The PL spectra show two bands, around 1.87 and 2.16 eV, for all the samples, while a third broad band at lower energy shows up and shifts to the red as OPP increases. Our results indicate that silicon-related room temperature PL emission is correlated with the stoichiometry of the SiO x and to the formation of silicon crystals embedded in a silicon dioxide matrix.
Influence of Thermal Annealing on the Properties of Sputtered Si Rich Silicon Oxide Films
Solid State Phenomena, 2010
Thin SiOx films deposited by reactive r.f. magnetron sputtering of Si at partial pressure ratios R between oxygen and argon in the range 15%-0.03% are studied. X-ray photoelectron spectroscopy and Variable angle spectroscopic ellipsometry prove enrichment with Si of the layers deposited at R < 0.5 %. Ellipsometric data give information about the refractive index and extinction coefficient of the films. Atomic Force Microscopy results show that for all samples high temperature annealing at 1000oC leads to a decrease of the surface roughness.
Electronic state characterization of SiO x thin films prepared by evaporation
SiO x thin films with different stoichiometries from SiO 1.3 to SiO 1.8 have been prepared by evaporation of silicon monoxide in vacuum or under well-controlled partial pressures of oxygen ͑P Ͻ 10 −6 Torr͒. These thin films have been characterized by x-ray photoemission and x-ray-absorption spectroscopies, this latter at the Si K and L 2,3 absorption edges. It has been found that the films prepared in vacuum consists of a mixture of Si 3+ and Si + species that progressively convert into Si 4+ as the partial pressure of oxygen during preparation increases. From this spectroscopic analysis, information has been gained about the energy distribution of both the full and empty states of, respectively, the valence and conduction bands of SiO x as a function of the O / Si ratio. The characterization of these films by reflection electron energy-loss spectroscopy ͑REELS͒ has provided further evidences about their electronic structure ͑band gap and electronic states͒ as a function of the oxygen content. The determination of the plasmon energies by REELS has also shown that the films prepared by evaporation in vacuum consist of a single phase which is characterized by a density ͑1.7 g cm −3 ͒ lower than that of SiO 2 ͑i.e., 2.2 g cm −3 ͒ or Si ͑i.e., 2.4 g cm −3 ͒. The optical properties ͑n and k͒ of the films as a function of the O / Si content have been deduced from the analysis of REELS spectra in the energy range from 4 to 20 eV. It has been also shown that the O / Si ratio in the films and several spectroscopic parameters such as the Auger parameter or the energy of bulk plasmons present a linear relationship and that this linear dependence can be used for a rapid characterization of SiO x materials. By contrast, the band-gap energy changes differently with the O / Si ratio, following a smooth linear increase from about 3.8 eV for SiO 1.3 to ca. 5.0 eV for SiO 1.7 and a jump up to 8.7 eV for SiO 2 . These results indicate that the random-bonding model does not apply to thin films prepared by evaporation under our experimental conditions. Other distributions of Si n+ states can be induced if the films are excited with an external source such as heat or photon irradiation. In this case the electronic properties vary and the previous linear correlations as a function of the oxygen content do not hold any longer.
Annealing effects in the PECVD SiO2 thin films deposited using TEOS, Ar and O2 mixture
Microelectronics Reliability, 2000
In this work, we present the results obtained on the characterization of silicon oxide thin ®lms deposited by plasma enhanced chemical vapor deposition (PECVD) using a mixture of tetraethylorthosilicate (TEOS), oxygen and argon. The electrical characteristics of the implemented MOS capacitors, after the annealing process (600°C), showed an increase in the break-down strength as well as the eective charge density. Ó
Electrical characterization of high-pressure reactive sputtered ScO x films on silicon
Thin Solid Films, 2011
metal-insulator-semiconductor capacitors have been electrically characterized. Scandium oxide was grown by high-pressure sputtering on different substrates to study the dielectric/insulator interface quality. The substrates were silicon nitride and native silicon oxide. The use of a silicon nitride interfacial layer between the silicon substrate and the scandium oxide layer improves interface quality, as interfacial state density and defect density inside the insulator are decreased.
Journal of Non-Crystalline Solids, 2006
A silicon oxide thin film barrier was prepared with various oxygen contents and its chemical composition, surface morphology and optical and barrier properties were related to the deposition conditions used. Our study showed that under Ar and O 2 assisted process conditions, a stoichiometric silicon oxide thin film formed at a critical oxygen content during deposition of 40-50%. The thin films deposited at the critical condition showed the lowest surface roughness giving similar or higher optical transmittance than that of the bare polycarbonate (PC) substrate. The boiling and tensile strength test performed on the thin film deposited with assisted ions before the deposition process showed improvement in the adhesion between the oxide layer and the polymer substrate. In addition, interface modification to improve for improving the barrier layer properties of the silicon oxide thin film was achieved through the introduction of dual ion beam sputtering without pre-treatment.
Journal of Applied Physics, 2000
The effect of rapid thermal annealing processes on the properties of SiO2.0 and SiN1.55 films was studied. The films were deposited at room temperature from N2 and SiH4 gas mixtures, and N2, O2, and SiH4 gas mixtures, respectively, using the electron cyclotron resonance technique. The films were characterized by Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance spectroscopy. According to the FTIR characterization, the SiO2.0 films show continuous stress relaxation for annealing temperatures between 600 and 1000 °C. The properties of the films annealed at 900-1000 °C are comparable to those of thermally grown ones. The density of defects shows a minimum value for annealing temperatures around 300-400 °C, which is tentatively attributed to the passivation of the well-known E' center Si dangling bonds due to the formation of Si-H bonds. A very low density of defects (5×1016 cm-3) is observed over the whole annealing temperature range. For the SiN1.55 films, the highest structural order is achieved for annealing temperatures of 900 °C. For higher temperatures, there is a significant release of H from N-H bonds without any subsequent Si-N bond healing, which results in degradation of the structural properties of the film. A minimum in the density of defects is observed for annealing temperatures of 600 °C. The behavior of the density of defects is governed by the presence of non-bonded H and Si-H bonds below the IR detection limit.
The structure of Si–SiO2 layers with high excess Si content prepared by magnetron sputtering
Thin Solid Films, 2009
Si-SiO 2 layers with high excess Si content prepared by magnetron co-sputtering of Si and SiO 2 and subsequently annealed were studied by electron paramagnetic resonance and photoluminescence methods. It was shown that adding oxygen during the deposition run or aging in air of as-deposited films influences the characteristics of the oxide layer surrounding the silicon crystallites. It was found that for layers with more than 55 vol.% of excess silicon the silicon crystallites are oriented. After high-temperature annealing not all the excess silicon was in crystalline form but part of it was in the amorphous phase. The depth distribution of the crystallites was found to be homogeneous while the distribution of amorphous silicon has a maximum around the middle of the layer.
Oxide modification due to high temperature processing of Si/SiO2/Si structures
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms - NUCL INSTRUM METH PHYS RES B, 1994
Si/SiO, /Si structures have beea subjected to 6 h anneals at 1320°C and defects generated by the annealing process revealed by ultra-violet and X ray irradiation and by hole injection. Two types of oxygen-vacancy related defects have been detected in the oxide by electron spin resonance, one involving Si interstitials.