Silicon Oxide Nitride Research Articles

Large-Area Layer Counting of Two-Dimensional Materials Evaluating the Wavelength Shift in Visible-Reflectance Spectroscopy

An advanced and highly scalable approach for determining the number of layers of two-dimensional (2D) materials via optical spectroscopy is introduced. Based on appropriate subjacent layer stacks, the reflectance spectra of the 2D material assemblies exhibit wavelength shifts in distinct minima, which are linearly related to the number of layers. A linear correlation enables straightforward data interpretation, which is essential for implementing simple and comparatively fast measurement routines for process control on wafer scale. The structure of the optical layer stacks as well as the complex refractive indices of 2D materials were found to strongly influence the spectral position of the reflectance minima as well as the magnitude and the linearity of the wavelength shifts. We experimentally prove this method to be applicable for large-area layer counting of subsequently stacked chemical vapor deposition graphene films on a layer stack consisting of silicon nitride and silicon oxide. The measurement re...

Polarization beam splitter based on a silicon nitride-silica-silicon horizontal slot waveguide.

A novel compact polarization beam splitter (PBS) based on a silicon nitride-silica-silicon horizontal slot waveguide is numerically proposed, to the best of our knowledge. In the slot waveguide, the transverse electric (TE) mode propagates through the silicon layer, while the transverse magnetic (TM) mode is confined in the slot region. By utilizing an asymmetric directional coupler (DC) and bent directional coupler (bent DC) consisting of a slot waveguide and a thin silicon waveguide, PBSs with 14.6μm (DC) and 5.2μm (bent DC) coupling regions are obtained. Without cascading other structures, the DC PBS shows a low insertion loss (IL) of 0.4 (0.2)dB and high extinction ratio (ER) of 31.56 (24.61)dB for a TE (TM) port around 1.55μm, while the IL and ER of the bent DC PBS are 0.4 (0.15)dB and 35.83 (21.74)dB, respectively. The proposed PBSs also have a good fabrication tolerance and broad bandwidth (>40 nm) for an ER of >20 dB.

Reduced metal contamination from crucible and coating using a silicon nitride based diffusion barrier for the growth of cast quasi-single crystalline silicon ingots

During the crystallization of directionally solidified silicon such as multicrystalline or cast quasi-single crystalline silicon, the diffusion of metal impurities from crucible and coating into the solid silicon ingot at high temperatures creates a severe contamination issue in the edge region of the ingot, the so called red zone. We present an effective diffusion barrier which greatly reduces this detrimental metal diffusion. Silicon wafers are coated with a layer system of silicon oxide and silicon nitride by chemical vapor deposition and are placed on the bottom of the crucible. Using this technique, the metal contamination in the red zone can be reduced by about one order of magnitude. This leads to better solar cell performance of wafers fabricated from this ingot area. Also, less ingot material has to be discarded leading to higher wafer yield per ingot.

Novel metallization processes for sub-100 nm magnetic tunnel junction devices

In this work, a novel method consisting of side-wall passivation and a top-metal reveal process is proposed for spintronics devices based on magnetic tunnel junctions (MTJs). The method can efficiently protect ferromagnetic metals and magnesium oxide, which are the key materials of MTJs, and effectively establish electrical contact with the interconnect metals for perpendicular MTJs (p-MTJs). The scheme consists of the passivation of MTJs with dual dielectrics – silicon nitride and silicon oxide – followed by planarization and selective wet etching. The proposed integration scheme was successfully demonstrated with 80-nm-diameter p-MTJ devices.

Microscopic-Stress-Induced retardation between amorphous silicon nitride and amorphous indium zinc oxide having different stresses

It is very important to increase the contrast ratio in liquid crystal display (LCD) TV using polymer-stabilized vertical alignment (PS-VA) mode. The luminance of the black state is greatly reduced by changing the parameters of the polarizer, the color filter, and the liquid crystal. However, these have the side effect of reducing the characteristics such as the transmittance, the response time, and the viewing angle. In this paper, the luminance of the black state can be reduced by lowering the stress induced retardation at the edge of pixel electrode without changing the materials in the PS-VA mode. It has been shown for the first time that the stress difference in the heterogeneous layers such as amorphous indium zinc oxide (a-IZO) and amorphous silicon nitride (a-SiNx) can optically create birefringence in the microscopic region. By controlling the stress difference in the heterogeneous membrane, the microscopic-stress-induced retardation (MSIR) could be lowered and the contrast ratio of the PS-VA mode could be increased up to 10%.

Dual‐Function Light‐Trapping: Selective Plating Mask of SiOx/SiNx Stacks for Silicon Heterojunction Solar Cells

Reducing the production cost of highly efficient silicon heterojunction (SHJ) solar cells is essential for their large‐scale commercialization. Replacing screen printed silver contacts with plated copper is an effective way. However, one needs to deal with the process compatibility without sacrificing the cell performance. In this work, a layer stack of silicon oxide and silicon nitride (SiOx/SiNx) is proposed, serving dual functions of light‐trapping and selective copper plating mask. The SiOx/SiNx stack is prepared by plasma enhanced chemical vapor deposition (PECVD) on a tungsten doped indium oxide (IWO) layer. Optimized SiOx/SiNx/IWO stacks in SHJ solar cells with silver contacts result in excellent anti‐reflection properties and improved external quantum efficiency. A short circuit current density gain of 1.16 mA cm−2 is achieved without the loss in fill factor. This SiOx/SiNx stack is tested as in‐situ deposited selective plating mask for a front‐side copper plating process. An in‐house made light induced plating tool is utilized. A screen printed silver finger is applied as a seed layer for copper plating. The bulk resistivity of Cu/Ag finger reduces to 4.1 E‐6 Ω · cm, which is lower than that of low temperature silver paste (around 6 E‐6 Ω · cm) before copper is plated on it. The dual functions of SiOx/SiNx stack and the process are proven, indicating a good potential for further improving photoelectric properties of SHJ solar cells after well optimization.

STATE, TRENDS, AND STRUCTURE OF THE WORLD NANO-POWDER MARKET

The purpose of this study is to provide a comprehensive analysis of the global nanopowder market. Materials and methods. The study used such research methods as system-logical method, method of statistical generalization, comparative and factor analysis. Research results. It is known that nanopowders are obtained by chemical, physical, physico-chemical and mechanical methods. One of the major problems in the production of nanopowders is the tendency of nanoparticles to form aggregates and agglomerates that complicate the production of compact materials. To overcome the forces of agglomeration, a mechanical force or an increase in the sintering temperature must be applied. According to estimates from the consulting company Lux Research, in 2012, the nanotechnology market was $ 190.3 billion. Its annual growth is 15-17%. The world market leaders are the United States ($ 59 billion), Europe ($ 47 billion) and the Asia Pacific region ($ 9.4 billion). The US is the leader in both the commercial market and the number of publications (about 25,000 in 2015) and patents in nanotechnology (45% of patents). Following the results of 2015, more than $1.4 trillion worth of nanotechnology products were manufactured. In the structure of production of nanoproducts the chemical industry, scientific researches (intermediary products, as a rule, not serial) and electronics are leading. Global investments in nanotechnology in 2015 totaled $ 18.1 billion. This indicator increased by 18% compared to 2013. Corporate investments ($ 8.6 billion) became the main source of financing (public - only $ 8.3 billion). The leaders in terms of public investment are the US and the EU. Experts estimate that, by 2020, investment leadership may shift to Japan. Today, the leader in the nanomaterials market is the United States with a projected revenue level of 2018 of $ 1.46 billion. The main products on the world market for nanopowders are metal oxide powders. In the product group of metal oxides 4/5 the production volume accounts for the three most common types of raw materials: silica (SiO2), titanium dioxide (TiO2) and alumina (Al2O3). At the same time, silica occupies more than half of all production, alumina - 18% and titanium dioxide - 10%. The most available oxides are oxides of iron, zinc, cerium, zirconium, cuprum, magnesium, yttrium. The most complex oxides and mixtures are: tin oxide, barium titanate, cobalt carbide, silicon nitride and indium tin oxide. An analysis of the patents presented for nanopowder research has shown that the most promising area of ​​scientific development is aluminum and precious metal nanopowders. Conclusions. Analysis of the world nanopowder market makes it possible to identify the following indicators that characterize its development: the common problem in the nanomaterials market is high cost of production, low volume of production and accessibility for the end consumer; the most developed nanopowder markets: USA, Europe and Asia-Pacific; projected growth rates during 2015-2020 The three largest components of the nanomaterials market: energy, production of catalysts, structural materials - 60%, 13% and 30% respectively; production of metal oxide products prevails in the world market of nanopowders; the most common types of raw materials: silica) - more than half of all production, titanium dioxide - 10% and alumina - 18%.

Production of nanopowders from physical vapor deposited films on nonmetallic substrates by conjunctional freezing-assisted ultrasonic extraction method

A new technique to extract nanoscale powders from thin films deposited by a physical vapor deposition method on nonmetallic substrates is proposed. Powders were extracted from films of different materials, such as silicon, nickel, copper, iron, aluminum and cobalt, and compounds, such as aluminum nitride, aluminum oxide, copper oxide, iron oxide, nickel cobaltite, nickel ferrite, nickel oxide, silicon carbide, silicon nitride and silicon oxide. These thin films were deposited on glass substrates by magnetron sputtering, pulsed-laser deposition, spray pyrolysis or thermal evaporation, and the particle sizes of the extracted powders were comparable to those of film samples. This technique is fast, low cost, reliable, highly clean and appropriate for large-scale samples.

Self-Amplified Tunneling-Based SONOS Flash Memory Device With Improved Performance

In this paper, we report on the assessment of self-amplified silicon–oxide–nitride–oxide–silicon (SONOS) memory device architecture for sub-50-nm gate length ( ${L}_{g}$ ) through calibrated simulations. Self-amplification (SA) effect in tunnel field-effect transistor-based SONOS (T-SONOS) memory device has been analyzed. Results show that memory window ( $\Delta {W}$ ) in T-SONOS cell increases as buried oxide thickness increases due to capacitive coupling between the front and back gates. Although the enhanced $\Delta {W}$ can also be achieved in inversion-mode SONOS (I-SONOS) device, its performance is deteriorated when the gate length is scaled down. We have compared the performance of I-SONOS and T-SONOS memory devices for ${L}_{g}$ varying from 100 to 25 nm. Results highlight that I-SONOS device cannot be programmed at ${L}_{g} ={25}$ nm and thus deteriorate the memory operation. However, SA T-SONOS at ${L}_{g} = {25}$ nm achieves ${W} \sim {6}$ V. In addition, the effect of underlap on the performance of T-SONOS cell has been analyzed, and it is shown that memory operation of 25-nm T-SONOS device can further improved with a drain side underlap of 20 nm. This paper provides new opportunities to design SA T-SONOS memory device for the next-generation nonvolatile memories.

UV Total Dose Nonvolatile Sensor Using Silicon–Oxide–Nitride–Oxide–Silicon Capacitor with Oxy-nitride as Charge-trapping Layer

UV Total Dose Nonvolatile Sensor Using Silicon–Oxide–Nitride–Oxide–Silicon Capacitor with Oxy-nitride as Charge-trapping Layer

Self-Aligned Contacting Processes for the 80 nm p-MTJ Device Fabrication by Wet Approach

In this work, a novel process integration scheme for p-MTJ devices’ passivation and contacting was proposed. The method can efficiently protect the ferromagnetic metals and the magnesium oxide which are the key building block of p-MTJs, and effectively make electrical contact with the interconnect metals for p-MTJs. The scheme consists of passivation of p-MTJs with dual dielectrics - silicon nitride and silicon oxide, followed by planarization and selective wet etch. The proposed integration scheme was successfully demonstrated with 80 nm size p-MTJ devices.

The SiO2 and SiNx Multilayer Thin Film Deposition for Encapsulation of OLED Using a NSi-01 Single Precursor By Peald

OLEDs (Organic Light-Emitting Diodes) are already being used in many mobile devices and TVs, and the next generation of OLED displays will be flexible and foldable. These foldable and flexible OLED displays tend to reduce the radius of curvature under 2.5R and require excellent encapsulation characteristics at thin thicknesses. To satisfy these requirements, multilayer barrier films are considered to be indispensable for the OLEDs. Unlike a single thin film such as SiO2 and SiNx, which is currently applied, the multi-layer itself can produce an antireflection film effect due to a difference in refractive index of each thin film in laminated thin films, thereby reducing diffuse reflection. Also It is effective for blocking ultraviolet rays and loss stress.[1], [2]. Recently, The ALD (Atomic Layer Deposition) method is used for developing thin film encapsulation technology, due to advantages of self limiting surface reaction and controlling the fraction of reaction. In this paper, SiO2, SiNx and multi-layer thin films were deposited on PEN (polyethylene naphthalate) films by using the NSi-01 single precursor by PEALD (Plasma Enhanced Atomic layer Deposition) technique at low temperature (90℃), and thin film thickness and refractive index were measured using a M2000D Spectroscopic Ellipsometer from Woollam. Also, the WVTR (Water Vapor Transmission Rate) characteristics of the deposited films were confirmed using a MOCON Aquatran 2. The refractive index of the SiO2 and SiNx film was 1.47 and 1.85 respectively, which confirmed the possibility of antireflection effect through the multi-layer thin film. The WVTR characteristics were measured according to the thickness of SiO2 and SiNx film over 100hrs. The both deposited SiO2 and SiNx thin film below 150Å showed poor or breakdown encapsulation property (Fig.1). In order to overcome this, the SiO2 film and SiNx film were stacked in order. The deposited multi-layer film showed excellent WVTR characteristics with a breakdown prevention of encapsulation property at thin thickness. Also, 2 to 3% of the carbon in the deposited SiNx film is expected to lower film stress and maintain the flexibility of the entire film (Fig. 2). [3] From this research, we confirmed the possibility of deposit multi-layer thin film consist of silicon oxide film and nitride film in one chamber using a one precursor by PEALD. Especially, multilayer type thin film deposition suggested the possibility of preventing reflection and water vapor simultaneously. References Hemant Kumar Raut,*a V. Anand Ganesh,a A. Sreekumaran Nairb and Seeram Ramakrishna*acd “Anti-reflective coatings: A critical, in-depth review” Energy Environ. Sci.,3784, 2011S. Chhajed, M. F. Schubert, J. K. Kim, and E. F.Schubert, “Nanostructured Multilayer Graded-indexAntireflection Coating for Si Solar Cells with Broadbandand Omnidirectional Characteristics”, Applied Physics Letters, vol. 93, p. 251108, 2008KwanDo Kim, SeokHee Jang, JongMin Kim* and SangMok Chang, “Characterization of Thin Film Passivation for OLED by PECVD” , Korean Chem. 575, 2012 Figure 1

Investigations of the impact of initial stresses on fracture and delamination risks of an avionics MEMS pressure sensor

Silicon based pressure sensors often take advantage of piezo-resistive gages which are normally embedded by multiple silicon oxide and silicon nitride layers where gold lines form a Wheatstone bridge (Meti et al., 2016; Bae et al., 2004 [2]). Because of manufacturing – stepwise deposition of multiple layers – significant layer residual stresses occur in the GPa range in tension and compression (Zhou et al., 2017 [3]). But also anodic bonding of the silicon MEMS device on usually glassy substrates results in additional initial stresses (Chou et al., 2009 [4] and Sandvan et al. [5]). Especially in avionics MEMS applications such stresses by far exceed the stresses arising under sensor operation and determine the major risks for cracking and delamination. Furthermore, those stresses could lead to a signal drift of the overall sensor over a long period of time — another important trustworthiness risk (Espinosa and Prorok, 2003 [6]).

Environmental Electrometry with Luminescent Carbon Nanotubes.

We demonstrate that localized excitons in luminescent carbon nanotubes can be utilized to study electrostatic fluctuations in the nanotube environment with sensitivity down to the elementary charge. By monitoring the temporal evolution of the cryogenic photoluminescence from individual carbon nanotubes grown on silicon oxide and hexagonal boron nitride, we characterize the dynamics of charge trap defects for both dielectric supports. We find a one order of magnitude reduction in the photoluminescence spectral wandering for nanotubes on extended atomically flat terraces of hexagonal boron nitride. For nanotubes on hexagonal boron nitride with pronounced spectral fluctuations, our analysis suggests proximity to terrace ridges where charge fluctuators agglomerate to exhibit areal densities exceeding those of silicon oxide. Our results establish carbon nanotubes as sensitive probes of environmental charge fluctuations and highlight their potential for applications in electrometric nanodevices with all-optical readout.

Passivation of Liquid‐Phase Crystallized Silicon With PECVD‐SiNx and PECVD‐SiNx/SiOx

Silicon nitride (SiNx) and silicon oxide (SiOx) grown with plasma‐enhanced chemical vapor deposition are used to passivate the front‐side of liquid‐phase crystallized silicon (LPC‐Si). The dielectric layer/LPC‐Si interface is smooth and layers are well‐defined as demonstrated with transmission electron microscopy. Using electron energy loss spectroscopy a thin silicon oxynitride is detected which is related to oxidation of the SiNx prior to the silicon deposition. The interface defect state density (Dit) and the effective fixed charge density (QIL,eff) are obtained from high‐frequency capacitance‐voltage measurements on developed metal‐insulator‐semiconductor structures based on SiOx/SiNx/LPC‐Si and SiOx/SiNx/SiOx/LPC‐Si sequences. Charge transfer across the SiNx/LPC‐Si interface is observed which does not occur with the thin SiOx between SiNx and LPC‐Si. The SiOx/SiNx/LPC‐Si interface is characterized by QIL,eff > 1012 cm−2 and Dit,MG>1012 eV−1 cm−2. With SiOx/SiNx/SiOx stack, both parameters are around one order of magnitude lower. Based on obtained QIL,eff and Dit(E) and capture cross sections for electrons and holes of σn = 10−14 cm s−1 and σp = 10−16 cm s−1, respectively, a front‐side surface recombination velocity in the range of 10 cm s−1 at both interfaces is determined using the extended Shockley‐Read‐Hall recombination model. Results indicate that field‐effect passivation is strong, especially with SiOx/SiNx stack.

Effect of the oxidization of Si3N4 powder on the microstructural and mechanical properties of hot isostatic pressed silicon nitride

The effect of nanosized oxidized silicon nitride powder particles on the microstructural and mechanical properties of hot isostatic pressed silicon nitride was studied. The starting <alpha> Si3N4 powders were oxidized for 10 and 20 h at 1000 °C in ambient air environment. An amorphous oxide layer was observed on the surface of Si3N4 powder particles using high resolution transmission electron microscopy (HRTEM) whose thickness increased with the oxidation time. The powders were hot isostatic pressed at 1500 °C and 1700 °C in nitrogen gas environment under 20 MPa for 3 h. Complete <alpha> to <beta> transformation was observed in Si3N4 samples sintered at 1700 C under 20 MPa for 3 h compared to Si3N4 samples sintered at 1500 °C. Silicon oxynitride (Si2N2O) was found in sintered samples whose amount increased with the oxidation time. The <beta> phase decreased with the increase of Si2N2O phase in the sintered samples. The flexural strength of samples sintered at 1700 °C is higher due to the higher amount of <beta>-Si3N4 phase than for samples sintered at 1500 °C. Decreasing flexural strength was observed with the oxidation time. Higher amount of oxygen in the base powders resulted in a higher Si2N2O content in the sintered Si3N4.

Heavy Ion Radiation Effects on a 130-nm COTS NVSRAM Under Different Measurement Conditions

The 6T SRAM cell with fast access speed and silicon–oxide–nitride–oxide–Silicon (SONOS) cell with nonvolatility in a 130-nm commercial-off-the-shelf (COTS) nonvolatile SRAM (NVSRAM) is exposed to heavy ion irradiation under different test conditions. In 6T SRAM mode, the influence of linear energy transfer (LET), supply voltage, ambient temperature, and periphery circuits on single-event effects (SEE) is studied and analyzed. The anomaly of multiple upsets proportion with increasing the LET value may be ascribed to the difference of ion track structure. The observed nonmonotonic relationship between the upset cross section and supply voltage can be explained by a competing mechanism of critical charge and collected charge in a sensitive node. In SONOS nonvolatile mode, the upset threshold of 60.9 MeV/(mg/cm2) and two types of errors are observed. The recoverable upset error may be caused by ion-induced discharge of nonvolatile cell and the hard error that can be annealed to vanish in room temperature probably results from the ion-induced charge trapping in oxide. The above results show that the 6T SRAM cell in this NVSRAM is vulnerable to SEE, whereas the SONOS nonvolatile cell is quite resistant. Based on the prediction of space upset rate, the potential applications and issues of this COTS NVSRAM and deep sub-micrometer SONOS process in space component are discussed.

Threshold voltage variation depending on single grain boundary and stored charges in an adjacent cell for vertical silicon–oxide–nitride–oxide–silicon NAND flash memory

The effects of single grain boundary (SGB) position and stored electron charges in an adjacent cell in silicon–oxide–nitride–oxide–silicon (SONOS) structures on the variations of threshold voltage (Vth) were investigated using technology computer-aided design (TCAD) simulation. As the bit line voltage increases, the SGB position causing the maximum Vth variation was shifted from the center to the source side in the channel, owing to the drain-induced grain barrier lowering effect. When the SGB is located in the spacer region, the potential interaction from both the SGB and the stored electron charges in the adjacent cell becomes significant and thus resulting in larger Vth variation. In contrast, when the SGB is located at the center of the channel, the peak position of potential barrier is shifted to the center, so that the influence of the adjacent cell is diminished. As the gate length is scaled down to 20 nm, the influence of stored charges in adjacent cells becomes significant, resulting in larger Vth variations.

Broadband angle-independent antireflection coatings on nanostructured light trapping solar cells

Backscattering from nanostructured surfaces greatly diminishes the efficacy of light trapping solar cells. While the analytical design of broadband, angle-independent antireflection coatings on nanostructured surfaces proved inefficient, numerical optimization proves a viable alternative. Here, we numerically design and experimentally verify the performance of single and bilayer antireflection coatings on a 2D hexagonal diffractive light trapping pattern on crystalline silicon substrates. Three well-known antireflection coatings, aluminum oxide, silicon nitride, and silicon oxide, which also double as high-quality surface passivation materials, are studied in the 400--1000 nm band. By varying thickness and conformity, the optimal parameters that minimize the broadband total reflectance (specular and scattering) from the nanostructured surface are obtained. The design results in a single-layer antireflection coating with normal-angle wavelength-integrated reflectance below 4% and a bilayer antireflection coating demonstrating reflection down to 1.5%. We show experimentally an angle-averaged reflectance of $\ensuremath{\sim}5.2%$ up to 60\ifmmode^\circ\else\textdegree\fi{} incident angle from the optimized bilayer antireflection-coated nanostructured surface, paving the path toward practical implementation of the light trapping solar cells.

Efficient and Stable CsPbBr3 Quantum-Dot Powders Passivated and Encapsulated with a Mixed Silicon Nitride and Silicon Oxide Inorganic Polymer Matrix.

Despite the excellent optical features of fully inorganic cesium lead halide (CsPbX3) perovskite quantum dots (PeQDs), their unstable nature has limited their use in various optoelectronic devices. To mitigate the instability issues of PeQDs, we demonstrate the roles of dual-silicon nitride and silicon oxide ligands of the polysilazane (PSZ) inorganic polymer to passivate the surface defects and form a barrier layer coated onto green CsPbBr3 QDs to maintain the high photoluminescence quantum yield (PLQY) and improve the environmental stability. The mixed SiN x/SiN xO y/SiO y passivated and encapsulated CsPbBr3/PSZ core/shell composite can be prepared by a simple hydrolysis reaction involving the addition of adding PSZ as a precursor and a slight amount of water into a colloidal CsPbBr3 QD solution. The degree of the moisture-induced hydrolysis reaction of PSZ can affect the compositional ratio of SiN x, SiN xO y, and SiO y liganded to the surfaces of the CsPbBr3 QDs to optimize the PLQY and the stability of CsPbBr3/PSZ core/shell composite, which shows a high PLQY (∼81.7%) with improved thermal, photo, air, and humidity stability as well under coarse conditions where the performance of CsPbBr3 QDs typically deteriorate. To evaluate the suitability of the application of the CsPbBr3/PSZ powder to down-converted white-light-emitting diodes (DC-WLEDs) as the backlight of a liquid crystal display (LCD), we fabricated an on-package type of tricolor-WLED by mixing the as-synthesized green CsPbBr3/PSZ composite powder with red K2SiF6:Mn4+ phosphor powder and a poly(methyl methacrylate)-encapsulating binder and coating this mixed paste onto a cup-type blue LED. The fabricated WLED show high luminous efficacy of 138.6 lm/W (EQE = 51.4%) and a wide color gamut of 128% and 111% without and with color filters, respectively, at a correlated color temperature of 6762 K.