Refractive Index Of SiO2 Film Research Articles

Properties of Silicon Dioxide Film Deposited By PECVD at Low Temperature/Pressure

conventional plasma enhanced chemical vapor deposition (PECVD) at low temperature/pressure with silane (SiH4) and nitrous oxide (N2O) as precursor gases. The ellipsometer and stress measurement system were used to test the thickness and refractive index uniformity of the SiO2 film fabricated. The effects of radio frequency (RF) power chamber pressure and N2O/SiH4 flow ratio on the properties of SiO2 film were studied. The results show that the refractive index of SiO2 film is mainly determined by N2O/SiH4 flow ratio .Moreover, the formation of SiO2 thin films is confirmed by Fourier transform infrared (FTIR) spectroscopy. The thickness and refractive indices of the films measured by ellipsometry C-V measurement show that the electrical properties are directly related to process parameters and Si/SiO2 interface. The MIS structures were also fabricated from optimized SiO2 layer to study C-V measurement and to estimate interface, oxide and effective border traps density. The deposited SiO2 films have good uniformity, compact structure, high deposition rate, low deposition temperature and controllable stress, which can be widely, used in semiconductor devices.

Optical Constants of SiO2 Films Deposited on Si Substrates

SiO2 films were deposited on single-crystalline silicon substrates by ion beam sputtering technology. Optical constants of SiO2 films are calculated from spectroscopic ellipsometry data, transmittance spectra and reflectance spectra by WVASE32 software, and the best fitted method is obtained for calculating optical constants of dielectric materials in the ultraviolet-visible-infrared (UV-VIS-IR) range. In the UV-VIS-NIR spectral range, refractive indices of SiO2 films are calculated separately by both ellipsometry data and reflectance spectra, and the obtained results are almost the same. Complex dielectric functions of SiO2 films in the IR spectral range are accurately calculated with infrared transmission spectra using the GenOsc model. The obtained accuracy complex refractive index of SiO2 films in the wavelength region from 0.19 μm to 25 μm is of great importance for the design of high quality coatings, such as ultra-low loss coating.

Effect of Drawing Speed on Properties of the Anti-Reflective SiO<sub>2</sub> Film Based on Glass

The anti-reflective SiO2 film on glass was prepared by sol-gel process and dip-coating method.The effect of drawing speed on properties of the SiO2 film was studied. The transmittance was tested by light spectrum transmittance testing system,the thickness and refractive index of SiO2 film was tested by spectroscopic ellipsometer. With increasing of the drawing speed from 100mm/min to 300 mm/min, the average of transmittance increment at first increased and then decreased, which reached the maximum 4.24% at the speed 150mm/min. The relations among transmittance, thickness (d) and refractive index (n) of the SiO2 film was dicussed.

Optical and interfacial layer properties of SiO2 films deposited on different substrates

SiO2 films were deposited on fused silica, silicon, glass, germanium, and sapphire substrates by an ion beam sputtering technique. The optical properties of SiO2 films on different substrates and interfacial layer properties between SiO2 films and different substrates were researched by the spectroscopic ellipsometry technique. The refractive indices of SiO2 films deposited on different substrates are about 1.477 at the wavelength of 632.8 nm. The optical anisotropy property of SiO2 films on fused silica substrate is the best. The impact of thermal treatment on surface roughness and interfacial layer properties between SiO2 films and Si substrates were also investigated. When the annealing temperature is 550°C, the least surface thickness and thinnest interface layer thickness between v films and silicon substrate can be achieved. The results indicate that the surface and interface layer properties between SiO2 films and silicon substrate can be greatly improved when the optimum annealing temperature is selected.

Effects of thermal treatment on infrared optical properties of SiO2 films on Si Substrates

The effects of thermal treatment on infrared optical properties of SiO2 films on Si substrates by ion beam sputtering technology were investigated. Complex refractive index of SiO2 films was calculated from Fourier transform infrared transmission spectrum from 400 to 4000cm−1. Absorption band properties associated with Si-O-Si stretching, bending, rocking mode at about 1080cm−1, 816cm−1, 460cm−1 were analyzed. With the increase of thermal annealing temperature, the absorption peak with Si-O-Si stretching, rocking mode shift to long wave number, but the bending mode shifts to short. After thermal treatment, the infrared optical constants are close to the value of the more stabilized thermal grown SiO2. So, it can be concluded that the structure of Si-O-Si network in SiO2 films deposited on Si was modified to the stable structure of thermal grown SiO2.

Optical-Property Profiling of SiO<sub>2</sub> Films Containing Si Nanocrystals Formed by Si<sup>+</sup> Implantation

A quantitative approach to determination of depth profiles of optical properties of Si-implanted SiO2 films based on spectroscopic ellipsometry (SE) is presented. From the SE measurements, the depth profiles of the complex refractive index of SiO2 films containing Si nanocrystals (Si-nc) are obtained with an effective medium approximation (EMA) in the wavelength range of 400-1200nm. The optical profiles obtained imply the existence of a wave-guide in the Si-doped SiO2 films.

Refractive Index Control of SiO2 Films by Pulsed Laser Deposition with Silicone Targets

We fabricated layered structures of SiO2 films with different refractive indices by pulsed laser deposition with silicone targets. The refractive index of SiO2 films could be controlled by the deposition rate. Lowering of the deposition rate helped to make a dense film, showing higher refractive index. A 0.4-µm-thick SiO2 cladding film deposited at 0.1 nm/pulse was first formed on the entire surface of a Si wafer, and then a 1-µm-thick SiO2 core film was deposited at 0.05 nm/pulse in a line of 1 mm width on the sample. The deposited films were free of impurities such as H2O and carbon. Transparent, tightly layered structures were obtained. The layered structures could also be fabricated on a flexible substrate consisting of a 100-µm-thick polyester sheet. Both samples functioned as an optical waveguide for a 633-nm He–Ne laser. The single-mode propagations were observed as designed.

Optical properties of PECVD TEOS-SiO2 Films

A plasma enhanced chemical vapor deposition (PECVD) system was utilized to deposit silicon dioxide thick film using vapor TEOS (Si(OC2H5)4) and oxygen. And the refractive index of SiO2 film was modified by adding vapor TMP (P(OCH3)3) for doping phosphorous. The p-doped SiO2, with its refractive index higher than the SiO2 buffer layer, could be used as the light transmitting core layer. The thickness and the refractive index were measured by means of prism couple system. Fourier transform infrared spectrometer, FTIR, was also used to understand the bonding characteristics and help improving the optical properties. By Marcatili's method, an optimal range of relative refractive index between core layer and cladding layer could be calculated. On this basis, a ridge-type of waveguide could be designed, and the distribution of light inside the waveguide could be simulated using Beam PROP software. In combining the photolithography and etching process to fabricate an optical waveguide structure, the light propagation loss could be measured by direct couple method. A single mode waveguide with sharp sidewall and smooth interface could be fabricated successfully.

Planarization of Film Deposition and Improvement of Channel Structure for Fabrication of Anti-Resonant Reflecting Optical Waveguide Type X-crossing Vertical Coupler Filter

To realize a low-sidelobe narrow-band Anti-resonant reflecting optical waveguide (ARROW)-type vertical coupler filter, the dependence of the refractive index and thickness profiles of compound glass films, deposited by a magnetron RF sputtering technique, on the mixture ratio of Ar and O2 gases was investigated. First, the depth profile of the refractive index of SiO2 films was planarized using pure O2 gas. Next, the lateral profiles of the refractive index and thickness of compound glass films were planarized by optimizing the gas mixture ratio of Ar and O2. When the mixture ratio was Ar : O2 = 1 : 3, the index variation of the Corning 7059 glass film was vastly improved from 0.3% to 0.05%, and the thickness variation was also improved from 9.0% to 4.0%. A similar improvement was also achieved for SK1 glass (from SCHOTT) and the Ta2O5–SiO2 binary glass system. A low sidelobe ARROW-type vertical coupler filter (VCF) with Corning 7059 glass and SK1 glass cores was demonstrated, using these deposition techniques and a wet chemical etching technique. In addition, the planarization technique of stripe-lateral-confinement (SLC)-ARROW waveguide was developed using a lift-off technique. A narrow band ARROW-type vertical coupler filter with Ta2O5–SiO2 cores was achieved by the lift-off and reactive ion etching (RIE) techniques.

ChemInform Abstract: Plasma‐Enhanced Chemical Vapor Deposition of Silicon Dioxide Using Tetraethylorthosilicate (TEOS).

AbstractThe refractive index of SiO2 films deposited from TEOS in an RF plasma using O2 as an oxidant is found to be 1.47, compared to 1.52 for TEOS‐N2O and TEOS in the absence of oxidant.

Optical properties of SiO_2–TiO_2 composite films

Optical properties of ion-beam sputter deposited SiO2–TiO2 composite films were examined in terms of composition dependence of the optical parameters, optical energy gap, and absorption character of these films. The complex refractive index of SiO2 film in the nondispersive region (λ > 310 nm) was 1.48–i0.0000, and for TiO2 (at λ > 525 nm) the index was 2.39–i0.0000 and the corresponding energy gaps 9.2 and 3.5 eV, respectively. Composite films of SiO2–TiO2 exhibited a continuous change in their optical properties. SiO2-like optical properties were dominant for the volume concentration of CTiO2≤0.25 and TiO2-like at higher concentrations.

Hysteresis free SiO2/InSb metal-insulator-semiconductor diodes

Hysteresis free capacitance-voltage (C-V) characteristics of SiO2/InSb metal-insulator-semiconductor (MIS) diodes are attained by introducing an in situ Br vapor etching technique into the fabrication process. Interface state density is also reduced by using this technique. It is found that following vapor etching, MIS C-V characteristics are strongly dependent on both the SiO2 film deposition temperature and oxygen flow rate. The optimum condition for SiO2 film deposition to obtain hysteresis free C-V curves and an interface state density of ≤1×1011 cm−2 eV−1 is determined for InSb MIS diodes. The area of the typical optimum conditions for MIS diodes is located in the oxygen flow rate range of 5–6 cc/min and the deposition temperature range of 200–210 °C. The refractive indices of SiO2 films are 1.44–1.45, the breakdown field strengths are more than 2×106 V/cm, and the dielectric constants for 1 MHz are typically 4.7 at 77 K, respectively.