Formation Of SiN Research Articles

Tricomponent direct co-assembly to nitrogen-doped, ordered mesoporous carbon@silica frameworks with enhanced nitrogen stability and multi-functionalities

Ordered mesoporous carbon@silica hybrid frameworks with high nitrogen content and good stabilities show great significance to improve their functionalities. Herein, we report novel nitrogen-doped (3.51 ∼ 4.62 wt%) and ordered mesoporous carbon@silica frameworks (N-OMC@SiO2) with reinforced nitrogen stability. The N-OMC@SiO2 were designed from tricomponent direct co-assembly between block copolymer template and mixed precursors containing urea and tetramethoxysilane without using additional solvent. The N-OMC@SiO2 have large BET surface areas (444.3 ∼ 674.9 m2/g), uniform mesoporous channels (5.8 ∼ 10.9 nm) with well-defined hexagonal symmetry, and stable carbon@silica “reinforced concrete” framework that can be transformed into carbon@silicon by controllable reduction. The nitrogen sites were firmly embedded into their frameworks via the formation of Si-N bonding. Thus, the resulted N-OMC@SiO2 exhibit multi-functionalities and enhanced recyclability in acid waste gas capture and gaseous sulfides catalytic utilization, better than many reported porous adsorbents and catalysts. This study may help develop stable and efficient N-OMCs nanocomposites for acidic gas selective removal.

Chemistry of size-segregated particles: study of sources and processes in N-NW India

PM0.95,PM0.95-1.5,PM1.5-3.0,PM3.0-7.2 and PM7.2-10 particles were collected simultaneously during summer season from Bikaner (BKR), Jhunjhunu (JHJ) and New Delhi (DEL) located in windward direction of south-westerly winds in north-northwestern, India and studied for mass concentrations and water-soluble inorganic ions (WSIIs). Organic carbon (OC) and elemental carbon (EC) were analyzed only for PM0.95. Particle mass concentrations, size distribution of WSIIs/elements suggested that winds selectively picked PM0.95 and PM3.0-7.2 from BKR and transported them downwind (DEL). Variations in WSIIs and elements were specific to ion/element, particle size and location(s). Secondary inorganic ions (SIN; NO3−, SO42−, NH4+) and Ca2+ were dominant ions compared to other ions and PM0.95 carried high WSIIs compared to other particles at all locations, due to more SIN formation in PM0.95. OC and EC increased significantly from BKR to DEL due to increasing combustion sources. Char-EC was more than soot-EC at all locations. Re-suspension of roadside/surface dust, and biomass burning were potentials sources of OC. Volatile organic compounds at DEL have resulted in formation of high secondary organic carbon. Major elements (MEs; Al, Ca, Fe, Mn, Ti) and trace elements (TEs; Ba, Sr, Zn, Cu, Cr, Pb, Co, Cd) were enriched in PM0.95 compared to other particles. Silica dilution effect resulted in lower enrichment ratios (ERs) of MEs with respect to Upper Continental Crust (UCC) whereas anthropogenic contributions for TEs, more in PM0.95, resulted in higher ERs. Homogenization effects on particle loading and composition were observed at BKR whereas lowering of wind speed and anthropogenic sources introduced heterogeneity at DEL.

The Grammar of the Fall

The aim of this analysis is to show the way of sin formation in one’s mind. As illustration for it, the biblical text is chosen. The story of original sin is quite short, but mysterious. How does it happen that Adam and Eve choose evil instead of God? Are they thrown into the sin or construct it by their selves?Using the semiotics of passions the author of the article tries to show the mechanism of transformation of the subject’s conscious-ness. The doubt about God makes subject to choose another axio-logical system. What is more, he is trying to become god himself. The formation of sin goes through the main phases: communica-tion with the tempter and interest → the doubt about God → eu-phoric visions of the future → rebellion against God → rebellious action.The consequences of sin are painful and not such euphoric as it seemed before. The person loses the harmony with everything in the world, he can only feel his own nakedness and vulnerability. However, notwithstanding human betrayal, God makes everything to save the mankind.

Band alignment at AlN/Si (111) and (001) interfaces

To advance the development of III-V nitride on silicon heterostructure semiconductor devices, we have utilized in-situ x-ray photoelectron spectroscopy (XPS) to investigate the chemistry and valence band offset (VBO) at interfaces formed by gas source molecular beam epitaxy of AlN on Si (001) and (111) substrates. For the range of growth temperatures (600–1050 °C) and Al pre-exposures (1–15 min) explored, XPS showed the formation of Si-N bonding at the AlN/Si interface in all cases. The AlN/Si VBO was determined to be −3.5 ± 0.3 eV and independent of the Si orientation and degree of interfacial Si-N bond formation. The corresponding AlN/Si conduction band offset (CBO) was calculated to be 1.6 ± 0.3 eV based on the measured VBO and band gap for wurtzite AlN. Utilizing these results, prior reports for the GaN/AlN band alignment, and transitive and commutative rules for VBOs, the VBO and CBO at the GaN/Si interface were determined to be −2.7 ± 0.3 and −0.4 ± 0.3 eV, respectively.

On the unimolecular decay and mechanism of formation of Si n + cluster ions

Dependences of the emission and fragmentation of sputtered Sin+ clusters with n =1–11 on the oxygen pressure near the surface are studied using secondary-ion mass spectrometry under Xe+-ion bombardment of a silicon surface. It is shown that taking into account the mutual reversibility of reactions of formation and unimolecular decay, the formation of Sin+ clusters under ion sputtering can be described within the framework of a mechanism of combinatorial synthesis.

Effect of Bias-Voltage in H2/N2 Plasma Treatment on Porous Low Dielectric Constant Materials

Porous low-dielectric constant (low-k) materials are needed for advanced technologies to improve signal propagation. Plasma treatments in interconnection fabrication have been considered to be critical steps to impact the low-k films’ properties. This study investigates the degradation of the porous low-k films by plasma exposure using several kinds of treatment conditions. Experimental results indicate that the increase in the dielectric constant and the degradation in the reliability for the plasma-treated low-k films were related to the decreased amount of Si-CH3 bonds and the absorbed amount of H2O or OH groups within the film. Plasma treatment with pure H2 gas extracts more CH3 groups from the porous low-k film and forms a larger amount of H2O or OH groups. Although the plasma-treated low-k films using N2 gas can suppress H2O or OH group formation, the increase in the dielectric constant is higher due to the formation of Si-N or C-N bonds. Plasma treatment using a mixture of H2/N2 gas can obtain a balance result in the dielectric constant increase and absorbed moisture uptake. Furthermore, increasing bias-voltage on the sample electrode during H2/N2 Plasma treatment can effectively suppress the degradation of the porous low-k dielectrics.

A study of nitrogen behavior in the formation of Ta/TaN and Ti/TaN alloyed metal electrodes on SiO2 and HfO2 dielectrics

We studied Ta, TaN, and sub-stoichiometric TaNx electrodes (obtained by nitrogen redistribution in Ta/TaN or Ti/TaN bilayers) deposited on thermal SiO2 and HfO2/IL (0.8 nm SiO2 IL, i.e., interlayer) stacks. Effective work-functions (WF) were extracted on MOS capacitor structures on SiO2 bevelled insulator of 4.2 eV for pure Ta, 4.6 eV for TaN, and 4.3 eV for sub-stoichiometric TaNx. This intermediate WF value is explained by TaN nitrogen redistribution with reactive Ta or Ti elements shifting the gate work-function toward the Si conduction band. The same electrodes deposited on an HfO2/IL dielectric showed different behavior: First, the Ta/HfO2/IL stack shows a +200 meV WF increase (towards the Si valence band) compared to the SiO2 dielectric stack. This increase is explained by the well-known HfO2/IL dipole formation. Second, in contrast to electrodes deposited on SiO2, sub-stoichiometric TaNx/HfO2 is found to have a lower WF (4.3 eV), than pure Ta on HfO2 (4.4 eV). This inversion in work-function behavior measured on SiO2 vs. HfO2 is explained by the nitrogen redistribution in Ta/TaN bilayer together with diffusion of nitrogen through the HfO2 layer, leading to Si-N formation which prevents dipole formation at the HfO2/IL interface.

Effect of Bias-Voltage in H2/N2 plasma Treatment on Porous Low Dielectric Constant Materials

Porous low-dielectric constant (low-k) materials are needed for advanced technologies to improve signal propagation. Plasma treatments in interconnection fabrication have been considered to be critical steps to impact the low-k films’ properties. In this study, the degradation of the porous low-k films by plasma exposure using several kinds of treatment conditions was investigated in this study. The increase of the dielectric constant and the degradation of the porous low-k film reliability were found to be related to the decreased amount of Si-CH3 bonds and the absorbed amount of H2O or OH groups in the film. Pure H2 gas plasma treatment extracts more CH3 group from the porous low-k film and forms a larger amount of H2O or OH groups. Although N2 gas plasma treatment can suppress H2O or OH group formation, the increase of the dielectric constant is higher due to the formation of Si-N or C-N bonds. The plasma treatment using a mixture gas of H2 and N2 can obtain a balance result in the dielectric constant increase and absorbed moisture uptake. Furthermore, introducing an increasing bias-voltage on the sample electrode during H2/N2 Plasma treatment can effectively suppress the degradation of the porous low-k films.

Interaction mechanism of ultrafine silica and poly(amido-amine) and dispersibility of the complexes in coatings

Ultrafine silicon dioxide was modified by NH2-teminated poly(amido-amine) (PAMAM) dendrimers to improve its dispersibility in the coatings. The complexes of nano-SiO2 and PAMAM were analyzed, and the modification mechanism was studied through density functional theory (DFT) in a gas phase with UB3LYP/6-31+G(d) and HF/6-31 G basis sets. Two stable conformers were gained: type A (Si+ was bound to the amine site) and C (Si+ was bound to the amide site), due to the chemical bond formation of SiN° and SiO, respectively. The electronic density population revealed the existence of the active binding regions such as the amide O and the amine N. The IR spectra for the lowest energy conformers was thoroughly analyzed and compared with the available experimental data.

Study of Modification Mechanism of Ultrafine Silica Modified by PAMAM

Ultrafine silicon dioxide were modified by -NH2-teminated poly(amido-amine) (PAMAM) dendrimers to improve their dispersibility in the coatings. The modification mechanism was studied through density functional theory (DFT) in the gas phase. Virous initial configurations of ion bound to PAMAM were established to investigate the structures and the energetics of the complexes. Two stable conformers are found: types A ( is bound to the amine site) and C ( is bound to the amide site). Types A and C indicate the chemical bond formation of Si-N and Si-O, respectively.

FT IR spectroscopy of silicon oxide layers prepared with perchloric acid

Chlorine oxidation is important methods for improvement of many properties such as passivation of mobile oxide charge, breakdown strength or enhancement of the minority-carrier lifetime in the underlying silicon. In this study we consider effects influencing the density of SiO2 layers formed by three different methods: thermal oxidation at 850°C, low temperature oxidation method by use of nitric acid – HNO3 (NAOS) and HClO4 afterward passivated with KCN/HCN solutions. Thicknesses of SiO2 layers determined by both capacitance–voltage (C–V) and XPS revealed fast oxidation rate compared with samples prepared by thermal oxidation. FT IR measurement showed that all absorption spectra are almost similar. Higher absorption of the sample prepared in HClO4 was observed. No SiCl bonds were visible. Calculated atomic density of the SiO2 layer obtained from IR measurements was lowest for sample formed in HClO4. Chlorine oxidation results in higher oxidation rate (higher thickness) and formation of stoichiometric SiO2 layer with lower density. Following KCN/HCN passivation causes formation of SiN, SiO and SiOH bonds at the expense of SiCl bonds.

Additional Nitrogen Ion-Implantation Treatment in STI to Relax the Intrinsic Compressive Stress for n-MOSFETs

Based on the stress extraction and measurement by the atomic-force-microscope-Raman technique with nanometer-level space resolution, the high compressive stress about 700 MPa on the Si critical dimension (CD) is observed in the current complementary metal-oxide-semiconductor (CMOS) transistor. The difference of thermal expansion between Si and Shallow trench isolation (STI) oxide during the total thermal budget for the standard CMOS transistor manufacture process results in this high compressive stress in Si CD and will further degrade the electron carrier mobility about 25% seriously. In order to relax this intrinsic-processed compressive stress in Si CD and recover this device performance loss, the novel process is proposed in this paper in addition to the usage of one-side pad-SiN layer demonstrated in our previous work. With this novel process of additional nitrogen-ion implantation (IMP) treatment in STI oxide, it can be found that the less compressive stress in the Si CD can be achieved by the smaller difference of thermal expansion coefficients between Si and highly n-doped SiO2 STI oxide. The formation of Si-N bonding in the STI-oxide region can be monitored by Fourier-transform infrared spectroscopy spectra, and the thermal expansion coefficients for Si, SiO2, and SiN are 2.6, 0.4, and 2.87 ppm/K, respectively. The relaxation of intrinsic-processed compressive stress in the Si CD of about 400 MPa by this proposed additional nitrogen IMP treatment contributes 14 % electron-carrier-mobility enhancement/recovery. The experimental electrical data agree well with the theoretical k.p calculation for the strained-Si theory.

The relaxation of intrinsic compressive stress in complementary metal-oxide-semiconductor transistors by additional N ion implantation treatment with atomic force microscope-Raman stress extraction

Based on the stress extraction and measurement by atomic force microscope-Raman technique with the nanometer level space resolution, the high compressive stress about 550 MPa on the Si active region (OD) is observed for the current complementary metal-oxide-semiconductor (CMOS) transistor. During the thermal budget for the standard manufacture process of the current CMOS transistor, the difference of thermal expansion coefficients between Si and Shallow Trench Isolation (STI) oxide results in this high compressive stress in Si OD and further degrades the electron carrier mobility seriously. In order to relax this intrinsic processed compressive stress in Si OD and try to recover this performance loss, the novel process is proposed in this work in addition to the usage of one-side pad SiN layer. With this novel process of additional N-ion implantation (IMP) treatment in STI oxide, it can be found that the less compressive stress about 438 MPa in Si OD can be achieved by the smaller difference of thermal expansion coefficients between Si and N-doped SiO2 STI oxide. The formation of Si-N bonding in N-doped SiO2 STI region can be monitored by Fourier transform infrared spectroscopy spectra and thermal expansion coefficients for Si, SiO2, and SiN are 2.6 ppm/K, 0.4 ppm/K, and 2.87 ppm/K, respectively. The effective relaxation of intrinsic processed compressive stress in Si OD about 112 MPa (from 550 MPa to 438 MPa) by this proposed additional N IMP treatment contributes ∼14% electron carrier mobility enhancement/recovery. The experimental electrical data agree well with the theoretical piezoelectricity calculation for the strained-Si theory.

Mechanisms for sealing of porous low-k SiOCH by combined He and NH3 plasma treatment

Porous dielectric materials, such as SiOCH, are used as the insulator in interconnect wiring in microelectronics devices to lower the dielectric constant and so decrease the RC time delay. Sealing of the pores (up to a few nm in diameter) is necessary to prevent degradation of the low-k properties during subsequent processing steps by diffusion of reactants through the pores into the material. Sequential treatment of porous SiOCH by He and NH3 plasmas is potentially a means of sealing pores while maintaining the low-k of the dielectric. The He plasma activates surface sites to accelerate the reactions responsible for pore sealing. NH3 plasma treatment completes the sealing through one of two mechanisms resulting from the adsorption of NHx radicals — catalyzing the formation of a densified surface layer or formation of Si-N, C-N and N-N bonds to bridge over the pore. In this paper, we discuss mechanisms for pore sealing bridging bonds based on results from an integrated computational investigation of the etching, cleaning, activation and sealing of porous SiOCH in sequential Ar/C4F8/O2, Ar/O2, He and Ar/NH3 plasmas. The authors found that pores in excess of 1 nm in radius are difficult to seal due to the inability of N-bonding to bridge the pore opening. Factors affecting the sealing efficiency, such as treatment time, average pore radius and aspect ratio are discussed.

Thermal degradation and fire performance of polysilazane-based coatings

This paper deals with the thermal degradation and fire performance of polysilazane (PZane) based coatings. PZanes are silicon–nitrogen backbone polymers and can be used in a wide range of applications. In this study, the fire performance of PZane coating as virgin or formulated materials were evaluated using a homemade fire testing methodology similar to the “Torch Test” fire testing method. It was shown that the performance of the PZane coating can be improved incorporating fire retardant additives. Degradation of the coating is then investigated. The mechanism of degradation of the PZane was elucidated analyzing the gas and condensed phases during the degradation. It was shown that the degradation occurs in three steps leading to the formation of SiN 4 and charring at high temperature. The kinetics of degradation of the three steps of degradation was also modeled in order to predict the degradation of the PZane coating in a fire scenario.

Core level photoemission study of nitrided hafnium silicate thin films

We present a synchrotron radiation and Al K α core level study of ultra-thin nitrided hafnium silicate thins films, potential candidate for a high κ oxide to replace SiO 2. Nitriding the as deposited, uniform silicate results in the formation of Si-N and Hf-N bonds, with a nitrogen profile near the silicate/SiO 2 interface. Controlled etching reveals that the nitridation has proceeded beyond the silicate into the SiO 2 bottom oxide, without degrading the sharp silicate/SiO 2 interface. The 1.2 nm Hf 0.4Si 0.6O 2 nitrided silicate on 0.6 nm SiO 2 has an estimated equivalent oxide thickness of 1.1 nm.

Named Entity Recognition in Vietnamese documents

NamedEntityRecognition (NER) aimstoclassify wordsin a documentintopre-definedtarget entity classes and is now considered to be fundamental for many natural language processing tasks such a si nformation retrieval, machine translation, information extraction and question answering. This paper presents the results of an experiment in which a Support Vector Machine (SVM) based NER model is applied to the Vietnamese language. Though this state of the art machine learning method has been widely applied to NER in several well-studied languages, this is the first time this method has been applied to Vietnamese. In a comparison against Conditional Random Fields (CRFs) the SVM model was shown to outperform CRF by optimizing its feature window size, obtaining an overall F-score of 87.75. The paper also presents a detailed discussion about the characteristics of the Vietnamese language and provides an analysis of the factors which influence performance in this task.

Effects of plasma treatment on the high frequency characteristics of Cu/Ta/hydrogen silsesquioxane (HSQ) system and electrical behaviors of Cu/Ta/HSQ/Pt MIM capacitors

With the increasing of the operating frequencies, insertion loss, signal propagation delay, and parasitic coupling capacitance become the significant problems. Small capacitance ( C) between interconnects is required to reduce the crosstalk, insertion loss, and RC delay associated with the metal interconnect system. Therefore, the interconnect with low dielectric constant ( k) material is required. Implementation of Cu/low- k dielectric is used for reducing insertion loss, RC delay, crosstalk noises, etc. In this work, Cu–hydrogen silsesquioxane (HSQ) systems are studied. Ammonia (NH 3) plasma is employed for the nitridation of HSQ. The effects of NH 3 plasma treatments on the high frequency characteristics (100 MHz to 20 GHz) of the interconnect structure Cu/Ta/HSQ and electrical behaviors of Cu/Ta/HSQ/Pt MIM capacitors are evaluated. Auger electron spectroscopy (AES) results suggest the diffusion of oxygen and copper atoms during copper annealing. This raises resistance of Cu interconnect and increases the conductance of the HSQ films. Hence, 400 °C-annealed Cu/Ta/HSQ interconnect systems become lossy at high frequencies (>2 GHz). Ammonia (NH 3) plasma bombardments break some of the Si–H bonds and the resulting dangling Si bonds increase the moisture absorption. Meanwhile, NH 3 plasma treatments reduce the leakage current by passivating the Si dangling bond and forming silicon nitride. The absorption of moisture and/or the formation of SiN x result in high dielectric constant of HSQ after prolonged NH 3 plasma bombardment. The dielectric constant of HSQ decreases and then increases with the increase of NH 3 plasma treatment time and a minimum dielectric constant of 2.2 is obtained after 50 s NH 3 plasma treatment at 200 W. Among various specimens in this study, the smallest insertion loss is 1.97 dB/mm at 20 GHz for the 400°C-annealed Cu/Ta/HSQ (NH 3-plasma-treated for 50 s). Appropriate NH 3-plasma bombardment helps to form a thin SiN x barrier layer which prevents the diffusion of oxygen without increasing the dielectric constant of the Cu–HSQ interconnect system. The leakage currents versus electric field characteristics suggest that a Schottky emission dominate conduction mechanism.

Reduction of dislocation density in heteroepitaxial GaN: role of SiH 4 treatment

TEM and AFM data show that a significant reduction of threading dislocations in heteroepitaxial GaN/Al 2O 3 grown by MOCVD has been achieved. The reduction has been obtained by growth interruption followed by annealing in silane (SiH 4). Density of threading dislocations in the GaN layer above the silane-exposed surface decreased to 5×10 7 cm −2 in comparison to 10 9 cm −2 in the layer below this surface. TEM data showed the existence of pyramidal pits at the silane-exposed surface. They were overgrown by the subsequent GaN layer. The presence of these pits indicates that the GaN surface was selectively etched during the silane flow. These pits were sites where dislocations drastically changed propagation direction from parallel to the c-axis to horizontal. Horizontal propagation of dislocations above the surface treated by silane (where formation of SiN was expected) suggests that the GaN layer in this region was grown in the lateral epitaxial overgrowth mode. EDX measurements performed at the interface between the SiH 4-treated GaN layer and the subsequently grown GaN did not show any presence of Si. Therefore, it is believed that the dislocation reduction is related to the lateral overgrowth above the pits and not to the formation of a SiN interlayer.

Dependence of hydrogen and oxygen incorporation on deposition parameters in photochemical vapor deposited mercury free silicon nitride films

Silicon nitride films have been deposited on p-type Si (100) by mercury-sensitized photo-chemical vapor deposition (photo-CVD) method varying deposition pressure and substrate temperature. Energy dispersive X-ray fluorescence spectra of the samples show that the incorporation of mercury in the films, if any, is below 20 ppm. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy studies show the incorporation of oxygen and hydrogen in all the films, which is a function of the deposition parameters. Higher substrate temperature favors the formation of SiH bonds and reverse is the case for the formation of SiNH bonds. The sample deposited at low temperature (170 °C) shows the presence of less unreacted silicon (4%) in comparison to the sample (12.5% unreacted silicon) deposited at higher deposition temperature (250 °C), but the variation of pressure shows no significant change in terms of the unreacted silicon. The incorporated hydrogen and oxygen passivate surface defects thereby influencing interface electronic state densities ( D it) and fixed insulating charges ( Q ss).