SiOxNy Films Research Articles

Preparation of SiOxNy Films by Facing-Target Sputtering System for Thin-Film Passivation Layers of OLEDs

Preparation of SiOxNy Films by Facing-Target Sputtering System for Thin-Film Passivation Layers of OLEDs

Tio2 Anti-Resonant Layer Arrow Waveguides

The simulation, fabrication and characterization of ARROW waveguides using dielectric films deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and Sputtering techniques, are presented in this work. Amorphous titanium oxide (TiO2) films were used as first cladding layer and silicon oxynitride (SiOxNy) films, as core and second cladding layers. Furthermore, homemade routines based in two computational methods were developed, for numerical simulations: Transfer Matrix Method (TMM) for the determination of the optimum thickness values of the Fabry-Perot layers, and the Finite Difference Method (FDM) for 2D design and determination of the maximum width that allows single-mode operation. The utilization of titanium oxide as first anti-resonant layer resulted in low optical attenuations, since high interlayer refractive index differences can be obtained.

Improved Density Of States and Effective Charge Density in Si/Pecvd Sioxny Interface

SiOxNy films deposited by the PECVD (Plasma Enhanced Chemical Vapor Deposition) technique at low temperatures from silane (SiH4) nitrous oxide (N2O) and helium (He) as precursor gases at different RF power and R = N2O/SiH4, in order to produce films with good SiOxNy/Si interface quality and low effective charge density were deposited and characterized. In order to compare the film structural properties with the interface (SiOxNy/Si) quality and interface charge density MOS capacitors were fabricated using these films as dielectric layer. The structure of the films was investigated by Fourier Transform Infrared Spectroscopy (FTIR). The MOS capacitors were characterized by low and high frequency capacitance (C-V) measurements, from where the interface state density, the effective charge density and the electrical breakdown were extracted. The better interface properties and a relatively low effective charge density were obtained for a film deposited with R=10 and RF power of 125 mW/cm2.

Characterization of MONOS nonvolatile memory by solid phase crystallization on glass

Solid phase crystallization (SPC) is carried out because of the best uniformity among the various crystallization methods. SPC poly-Si nonvolatile memory (NVM) is expected superior memory property in terms of stable reliability. This paper presents electrical properties of SPC poly-Si NVM on glass.Nonvolatile memory is an ideal portable storage device due to its characteristics of low-power consumption and compact size. Metal/oxide/nitride/oxide/silicon (MONOS) structure memory was fabricated on glass. Silicon oxynitride (SiOxNy) layer grown by nitrous oxide plasma served as a carrier tunnel layer, silicon nitride (SiNx) as charge trap region and silicon dioxide (SiO2) for blocking oxide were deposited to fabricate NVM on SPC poly-Si. SiOxNy, SiNx, and SiO2 films were deposited by using inductively coupled plasma chemical vapor deposition (ICP-CVD). Electrical properties of NVM on glass were analyzed gate voltage–drain current (VG–ID) and charge retention property. We obtained the NVM device with the programming voltage of −12 V, erasing of 11 V, and fast programming/erasing (P/E) time of 1 ms. It has a threshold voltage window memory of about 3.7 V and it still keep a wide threshold voltage window of 2.3 V after 10 years.

Effect of film chemistry on refractive index of plasma-enhanced chemical vapor deposited silicon oxynitride films: A correlative study

Thick SiOxNy films were deposited by radiofrequency (rf) plasma chemical vapor deposition using silane (SiH4) and nitrous oxide (N2O) source gases. The influence of deposition conditions of gas flow ratio, rf plasma mixed-frequency ratio (100 kHz, 13.56 MHz), and rf power on the refractive index were examined. It was observed that the refractive index of the SiOxNy films increased with N and Si concentration as measured via x-ray photoelectron spectroscopy. Interestingly, a variation of refractive index with N2O:SiH4 flow ratio for the two drive frequencies was observed, suggesting that oxynitride bonding plays an important role in determining the optical properties. The two drive frequencies also led to differences in hydrogen concentration that were found to be correlated with refractive index. Hydrogen concentration has been linked to significant optical absorption losses above index values of ∼1.6, which we identified as a saturation level in our films.

Improved effective charge density in MOS capacitors with PECVD SiOxNy dielectric layer obtained at low RF power

In this work SiOxNy films are produced and characterized. Series of samples were deposited by the plasma enhanced chemical vapor deposition (PECVD) technique at low temperatures from silane (SiH4), nitrous oxide (N2O) and helium (He) precursor gaseous mixtures, at different deposition power in order to analyze the effect of this parameter on the films structural properties, on the SiOxNy/Si interface quality and on the SiOxNy effective charge density. In order to compare the film structural properties with the interface (SiOxNy/Si) quality and effective charge density, MOS capacitors were fabricated using these films as dielectric layer. X-ray absorption near-edge spectroscopy (XANES), at the Si–K edge, was utilized to investigate the structure of the films and the material bonding characteristics were analyzed through Fourier transform infrared spectroscopy (FTIR). The MOS capacitors were characterized by low and high frequency capacitance (C–V) measurements, in order to obtain the interface state density (Dit) and the effective charge density (Nss). An effective charge density linear reduction for decreasing deposition power was observed, result that is attributed to the smaller amount of ions present in the plasma for low RF power.

Integration of optical waveguides with micro-incandescent light

In this work, we propose the integration of optical waveguides with a simple light source device. Light is emitted from an incandescent chromium micro-resistor embedded in a self-supported region of silicon oxynitride (SiOxNy) film. The waveguide structure is fabricated on a (100) silicon substrate using silicon oxynitride as the core and cladding layers. Bulk micromachining of the silicon substrate in KOH solution is used to free from the substrate the embedded micro-resistor, reducing the thermal dissipation of that region, allowing the resistor to heat up to incandescent temperatures. A comparison between a theoretical calculation and the experimental data indicate that the microlamp reaches 1160K before failure. After a microannealing process realized on the microlamp structure, it is possible to couple light into the waveguide and control the output power by adjusting the current that flows through the microlamp.

Structural and morphological studies on SiOxNy thin films

In this work, the structure and morphology of silicon oxynitride films deposited by the PECVD technique were studied. The films were deposited under two different conditions: (a) SiOxNy with chemical compositions varying from SiO2 to Si3N4 via the control of a N2O+N2+SiH4 gas mixture, and (b) Si-rich SiOxNy films via the control of a N2O+SiH4 gas mixture. The analyses were performed using X-ray near edge spectroscopy (XANES) at the Si-K edge, transmission electron microscopy (TEM) and Rutherford backscattering spectroscopy (RBS). For samples with chemical composition varying from SiO2 to Si3N4, the diffraction patterns obtained by TEM exhibited changes with the chemical composition, in agreement with the XANES results. For silicon-rich silicon oxynitride samples, the formation of a-Si clusters was observed and the possibility of obtaining Si nanocrystals after annealing depending on the composition and temperature was realized.

Synthesis of Nickel Disilicide Nanocrystal Monolayers for Nonvolatile Memory Applications

AbstractNickel silicide nanocrystals (NCs) were formed by thermally annealing SiOxNy films either implanted with Ni or coated with an evaporated Ni film. It is observed that the NCs grow into well-defined single crystalline structures embedded in a SiOxNy matrix, and that their size can be directly controlled by adjusting the concentrations of either silicon or nickel in the SiOxNy layer. The formation of well-defined NC monolayers was also demonstrated by depositing an ultra-thin Ni layer between two SiOxNy layers. These structures are shown to exhibit characteristic capacitance-voltage hysteresis suitable for nonvolatile memory applications.

Fabrication and characterization of metal-oxide-nitride-oxynitride-polysilicon nonvolatile semiconductor memory device with silicon oxynitride (SiOxNy) as tunneling layer on glass

A nonvolatile semiconductor memory (NVSM) device with a metal-oxide-nitride-oxynitride-polysilicon (MONOS) structure on a rough polysilicon (poly-Si) surface was fabricated using a low-temperature process and poly-Si thin film transistor (TFT) technology on glass. For the fabrication of the NVSM device on glass, plasma-assisted oxynitridation was carried out using nitrous oxide (N2O) as a reactive gas, due to the very rough surface of the poly-Si on glass annealed using an excimer laser. The ultrathin SiOxNy films obtained using the N2O plasma have a very uniform distribution on poly-Si and similar contents of oxygen and nitrogen in the peaks and valleys of the grains. The NVSM devices having a MONOS structure with a tunneling layer of ultrathin SiOxNy on glass have suitable switching and charge retention characteristics for data storage. The results demonstrate that the NVSM device made using low-temperature poly-Si TFT technology on glass reported in this paper can be used in various types of display devices.

Silicon Microtips with Self-Asligned Integrated Electrodes

In this work we present a method for the fabrication of silicon microtips with self-aligned anodes in order to obtain field emitting devices. The method is based on the anisotropic corrosion of the silicon substrate in KOH solutions and utilizes low stress SiOxNy films obtained by PECVD as masking material. These films are also utilized as structural material for mechanical support and electrical insulation of the electrodes. For the electrodes sputtered Cr films are utilized. Optical microscopy was utilized to determine the etch rate of the different stages during the microtip formation, in order to enable us to ascertain the total development time versus the initial mask dimensions. Matrixes with different number of microtips, 52 μm height and with diameter at the vertex bellow 1 μm, were fabricated and characterized. The results also show that the low stress SiOxNy film is essential to endure the corrosion process without structural damage.

Chemical States and Band-Gap Energy for Plasma-Nitrided Ultrathin Si Oxynitride Film

The chemical bonding structure and the band-gap energy of a plasma-nitrided siliconoxide dielectric with a thickness of 2 nm were studied for various annealing temperatures via X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. The N2 molecules were incorporated into the thin SiOxNy film, and the N2 molecules trapped inside the oxide layer during plasma nitridation were evaporated after annealing at low temperatures. XPS spectra revealed that N multi-components, designated as N-Si3, N-(SiOx)3, Si=N-O and N2, exist in the SiOxNy film. The band-gap energy of the SiOxNy thin film was about 7.4 eV. The elimination of N2 molecules did not have any effect on the band gap.

Properties of SiOxNy Thin Films Deposited with a Single Molecular Precursor by Using RF PECVD

We have deposited SiOxNy thin films on both Si(100) and glass substrates by using a tetraethyl orthosilicate (TEOS) single precursor at nitrogen flow rates of 0 ∼ 100 sccm by using a radiofrequency Plasma Enhanced Chemical Vapor Deposition (PECVD) method. The film growth orientation and microstructural characteristics were analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Deposition at higher nitrogen flow rates results in finer clusters with smaller grain sizes. Moreover, we used UV/Vis and FT-IR spectroscopy and ellipsometry to investigate the optical properties for various nitrogen flow ratios. As-deposited SiO2 films showed an amorphous structure, but samples annealed in an O2 ambient at 900 ◦C showed increased crystallinity. Also, the leakage current densities of the SiO2 and the SiOxNy films annealed at 900 ◦C in an O2 ambient were about 4.0 × 10−8 and 1.5 × 10−7 A/cm.

Improvement of Oxidation Property of SUS304 by Gas Barrier Coating

Stainless steel is widely used as a corrosion-resistant material. However, stainless steel corrodes at high temperature (573 K ~) due to the oxidization and grain boundary corrosion. To delay the oxidation at high temperature, coating of gas barrier film will be useful method. The purpose of this study is to improve the corrosion-resistant of SUS304 at high temperature by coating transparent SiOxNy film which has gas barrier properties. In addition, the influence of inlet gas mass flow rate ratio (N2/Ar+N2) on the oxidation properties at 773 K was examined. The SiOxNy films were deposited onto polished SUS304 by unbalanced dc magnetron sputtering apparatus. To examine the oxygen transmission rate (OTR) of SiOxNy films, PET was also used as substrate. The results showed that good OTR was obtained for N2/Ar+N2 < 0.12 on PET substrate. The similar tendency was obtained for SUS304 deposited film heated up to 773 K.

Modelling and Optimization for Deposition of SiOxNyFilms by Radio-Frequency Reactive Sputtering

SiOxNy films are deposited by reactive sputtering from aSi target in Ar/O2/N2 atmospheres. In order to achievethe control of film composition and to keep a high deposition rate atthe same time, a new sputtering model based on Berg's work is providedfor the condition of double reactive gases. Analysis based on thismodel shows that the deposition process can easily enter thetarget-poisoning mode when the preset gas flow (N2 in this work)is too high, and the film composition will change from nitrogen-rich toSiO2-like with the increase of oxygen supply while keeping theN2 supply constant. The modelling results are confirmed in thedeposition process of SiOxNy. Target self-bias voltagesduring sputtering are measured to characterize the different sputteringmodes. FTIR-spectra and dielectric measurements are used to testify themodel prediction of composition. Finally, an optimized sputteringcondition is selected with the O2/N2 flow ratio varyingfrom 0 to 1 and N2 supply fixed at 1 sccm. Average depositionrate of 17 nm/min is obtained under this selected condition, which hassuggested the model validity and potential for industry applications.

Study of SiOxNy as a bottom antireflective coating and its pattern transferring capability

To meet such challenges for the controlling of critical feature dimension at sub-50–100‐nm, it has been a general industrial trend to employ shorter wavelength (193nm, for example) lithography for better resolution and to use bottom antireflective coating (BARC) for a reduced standing wave formation and thus, a better critical dimensional control. Matching the optical constants (n,k) between the BARC, photoresist, and the underlayer to be patterned is critical for the elimination of such standing waves. SiOxNy and SiOxCy are two attractive inorganic BARC candidates in view of their easily adjustable optical constants by varying the deposition parameters and their etching compatibility with standard semiconductor plasma processes. In this article, SiOxNy films were prepared by plasma enhanced chemical vapor deposition approach. These films have been further characterized using x-ray photoelectron spectroscopy for chemical composition depth profile, Fourier transform infrared spectroscopy for local chemical bonding, and ellipsometry for optical constants. It has been demonstrated that the refractive indices of SiOxNy can be tuned from 1.6 to 2, while the absorption constants k can be adjusted from 0.1 to 0.9 by changing the process parameters, such as SiH4 flow rate, NH3 flow rate, and SiH4∕N2O ratio. To integrate the SiOxNy BARC film into the storage device manufacturing, the pattern transferring capability of SiOxNy has been discussed. A film stack structure of photoresist∕SiOxNy∕carbon or SiC hard mask∕magnetic device layer has been used to evaluate the performance of the SiOxNy BARC. SiOxNy film was opened via inductively coupled plasma etching with CHF3+O2 chemistry, while carbon and SiC hard masks were opened using He–O2 and SF6–He–O2 chemistries, respectively. SiF emission line at 388nm wavelength was used for end point during the SiOxNy etching, while the 778nm O peak and 685nm F peak have been used for carbon and SiC end pointing. The profiles of the etched SiOxNy and carbon∕SiC were analyzed by cross-section transmission electron microscopy.

Passivation Layers for Organic Thin-film-transistors

Inorganic layers, such as SiOxNy and SiOx deposited using plasma sublimation method, were tested as passivation layer for organic thin-film-transistors (OTFTs). OTFTs with bottom-gate and bottom-contact structure were fabricated using pentacene as organic semiconductor and an organic gate insulator. SiOxNy layer gave little change in characteristics of OTFTs, but SiOx layer degraded the performance of OTFTs severely. Inferior barrier properties related to its lower film density, higher water vapor transmission rate (WVTR) and damage due to process environment of oxygen of SiOx film could explain these results. Polyurea and polyvinyl acetates (PVA) were tested as organic passivation layers also. PVA showed good properties as a buffer layer to reduce the damage come from the vacuum deposition process of upper passivation layers. From these results, a multilayer structure with upper SiOxNy film and lower PVA film is expected to be a superior passivation layer for OTFTs.

Correlation of PECVD SiOxNy dielectric layer structural properties and Si/SiOxNy/Al capacitors interface electrical properties

In this work we produce and characterize SiOxNy films deposited by the plasma enhanced chemical vapor deposition (PECVD) technique at low temperatures from silane (SiH4) nitrous oxide (N2O) and helium (He) as precursor gases at different deposition pressures in order to analyze the effect of this parameter on the films structural properties and on the SiOxNy/Si interface quality. In order to compare the film structural properties with the interface (SiOxNy/Si) quality, MOS capacitors were fabricated using these films as dielectric layer. The structure and composition of the films were investigated by, X-ray absorption near-edge spectroscopy (XANES) at the N-K and O-K edges, Rutherford backscattering spectroscopy (RBS) and Fourier transform infrared spectroscopy (FTIR). The MOS capacitors were characterized by low and high frequency capacitance (C–V) measurements, from where the interface state density (Dit) and the effective charge density (Nss) were extracted. The film deposited at 120mTorr presented the best interface quality (Dit∼4×1010eV−1cm−2) and the higher concentration of N–H bonds. This result indicates that this pressure favors N–H incorporation in oxygen vacancies at Si–O–Si bridges, saturating the Si dangling bonds and consequently minimizing Si/SiOxNy interface defects, showing that it is possible to produce high quality dielectric layer by PECVD technique.

X-ray photoelectron spectroscopy and structural analysis of amorphous SiOxNy films deposited at low temperatures

We establish, using a tetrahedral model, the bonding properties of amorphous silicon oxynitride (a-SiOxNy) films deposited at low temperatures (LTs) by electron-cyclotron resonance chemical-vapor deposition (ECRCVD) on several substrates and under various conditions of gas flows and total gas pressure in a dilute mixture of SiH4+N2 in Ar. The atomic percentage of each tetrahedral unit incorporated in the film network is calculated from the deconvolution of the high-resolution x-ray photoelectron spectroscopy (XPS) spectra in the Si 2p3∕2 region and corroborated by the results obtained from both survey scans and the high-resolution XPS spectra in the N 1s region. The Si3N4 phase is the most important one and the only bonding unit which is incorporated in all our LT ECRCVD SiOxNy films. The incorporation of all the other component tetrahedrons depends strongly on growth conditions. The threshold values of the N∕Si atomic ratio for which intrinsic defects, such as Si–Si bonds, are not incorporated in the network depend on the O∕Si ratio incorporated in the films, mainly due to the competition between oxygen and nitrogen atoms in their reaction with silicon dangling bonds. The effect of the total gas pressure on the atomic percentages of the oxidation states present in the LT ECRCVD SiOxNy films is qualitatively similar to the effect of the ion bombarding energy or the plasma density. O–N bonds are present only in samples having high amount of oxygen and nitrogen in their networks. For these films, our results show unambiguously the presence of the N–Si2O tetrahedron and suggest that N–Si3−νOν tetrahedrons with ν⩾2 are not incorporated in their networks. A correlation is observed between the N–Si2O and the Si–O3(ON) tetrahedrons whose component peak is localized at (104.0±0.2)eV in the Si 2p3∕2 region of the XPS data, which suggests that both bonding units coexist in these films as some sort of complex bonding configuration.

Wear-out of Al–Ta2O5/SiO2–Si structures under dynamic stress

Abstract Wear-out of Al–Ta2O5/SiO2–Si stacked layers under dynamic current stresses was studied. It was found that a detrapping of negative charges occurs between the pulses, similarly to SiO2 and SiOxNy films. Additional consumption of the SiO2 interfacial layer results in a decrease of the gate voltage in some stages of the stress, depending upon the stress time and current density.