Showing papers on "Silicon nitride published in 2010"

Silicon Nitride for High‐Temperature Applications

Abstract: In this paper, a summary of the development of high-temperature silicon nitride (T>1200°C) is provided. The high-temperature capacity of various advanced commercial silicon nitrides and materials under development was analyzed in comparison with a silicon nitride without sintering additives produced by hot isostatic pressing. Based on this model Si 3 N 4 composed of only crystalline Si 3 N 4 grains and amorphous silica in the grain boundaries the influence of various sintering additive systems will be evaluated with focus on the high-temperature potential of the resulting materials. The specific design of the amorphous grain-boundary films is the key factor determining the properties at elevated temperatures. Advanced Si 3 N 4 with Lu 2 O 3 or Sc 2 O 3 as sintering additive are characterized by a superior elevated temperature resistance caused by effective crystallization of the grain-boundary phase. Nearly clean amorphous films between the Si 3 N 4 grains comparable to that of Si 3 N 4 without sintering additives were found to be the reason of this behavior. Benefit in the long-term stability of Si 3 N 4 at elevated temperatures was observed in composites with SiC and M o Si 2 caused by a modified oxidation mechanism. The insufficient corrosion stability in hot gas environments at elevated temperatures was found to be the main problem of Si 3 N 4 for application in advanced gas turbines. Progress has been achieved in the development of potential material systems for environmental barrier coatings (EBC) for Si 3 N 4 ; however, the long-term stability of the whole system EBC-base Si 3 N 4 has to be subject of comprehensive future studies. Besides the superior high-temperature properties, the whole application process from cost-effective industrial production, reliability and failure probability, industrial handling up to specific conditions during the application have to be focused in order to bring advanced Si 3 N 4 currently available to industrial application.

Method for low temperature bonding and bonded structure

Abstract: A method for bonding at low or room temperature includes steps of surface cleaning and activation by cleaning or etching. The method may also include removing by-products of interface polymerization to prevent a reverse polymerization reaction to allow room temperature chemical bonding of materials such as silicon, silicon nitride and SiO2. The surfaces to be bonded are polished to a high degree of smoothness and planarity. VSE may use reactive ion etching or wet etching to slightly etch the surfaces being bonded. The surface roughness and planarity are not degraded and may be enhanced by the VSE process. The etched surfaces may be rinsed in solutions such as ammonium hydroxide or ammonium fluoride to promote the formation of desired bonding species on the surfaces.

Silicon Nanocrystals Fundamentals Synthesis and Applications

Abstract: Introduction I. FUNDAMENTALS AND CHARACTERIZATION Fundamentals of Electronic Structure of Si Nanocrystals Surface Physics of Si Nanocrystals Linear and Nonlinear Optical Properties of Si Nanocrystals with Surface Plasmon Coupling Electrical Properties: Electrical Transport through SiO2-containing Si Nanocrystals Thermal Properties of Si Nanocrystals Surface Passivation and Functionalization of Si Nanocrystals Si Nanocrystals in Astrophysics Characterization of Si Nanocrystals with Diagnostic Techniques II. NANOCRYSTAL GROWTH Growth Kinetics of Si Nanocrystals in SiO2 Growth Kinetics of Si Nanocrystals in Silicon Nitride Chemical Synthesis of Si Nanocrystals. Colloidal Synthesis of Si Nanocrystals and Nanowires Ion Implantation Formation of Silicon Nanocrystals Formation of Silicon Nanocrystals by PECVD Deposition and Annealing Formation of Si Nanocrystals by Sputtering Sol-Gel Synthesis of Silicon Nanocrystals Synthesis and Functionalization of Silicon Nanocrystals by Means of Non-thermal Plasmas Silicon Nanocrystals in Porous Silicon and Applications III. APPLICATIONS Flash Memory Photonic Applications Lighting Applications Solar Cells Bioapplications and Sensor Applications Photosensitizers for Oxygen Molecules and Explosives

Second-Harmonic Generation in Silicon Nitride Ring Resonators

Abstract: The emerging field of silicon photonics seeks to unify the high bandwidth of optical communications with CMOS microelectronic circuits. Many components have been demonstrated for on-chip optical communications, including those that utilize the nonlinear optical properties of silicon[1, 2], silicon dioxide[3, 4] and silicon nitride[5, 6]. Processes such as second harmonic generation, which are enabled by the second-order susceptibility, have not been developed since the bulk $\chi^{(2)}$ vanishes in these centrosymmetric CMOS materials. Generating the lowest-order nonlinearity would open the window to a new array of CMOS-compatible optical devices capable of nonlinear functionalities not achievable with the?$\chi^{(3)}$ response such as electro-optic modulation, sum frequency up-conversion, and difference frequency generation. Here we demonstrate second harmonic (SH) generation in CMOS compatible integrated silicon nitride (Si3N4) waveguides. The $\chi^{(2)}$ response is induced in the centrosymmetric material by using the nanoscale structure to break the bulk symmetry. We use a high quality factor Q ring resonator cavity to enhance the efficiency of the nonlinear optical process and detect SH output with milliwatt input powers.

Improved electrical transport in Al-doped zinc oxide by thermal treatment

Abstract: A postdeposition thermal treatment has been applied to sputtered Al-doped zinc oxide films and shown to strongly decrease the resistivity of the films. While high temperature annealing usually leads to deterioration of electrical transport properties, a silicon capping layer successfully prevented the degradation of carrier concentration during the annealing step. The effect of annealing time and temperature has been studied in detail. A mobility increase from values of around 40 cm2/Vs up to 67 cm2/Vs, resulting in a resistivity of 1.4×10−4 Ω cm has been obtained for annealing at temperatures of 650 °C. The high mobility increase is most likely obtained by reduced grain boundary scattering. Changes in carrier concentration in the films caused by the thermal treatment are the result of two competing processes. For short annealing procedures we observed an increase in carrier concentration that we attribute to hydrogen diffusing into the zinc oxide film from a silicon nitride barrier layer between the zinc...

Mechanical properties of silicon nitride-based ceramics and its use in structural applications at high temperatures

Abstract: Silicon nitride (Si 3 N 4 ) based ceramics are gaining more and more attention due to their promising high-temperature thermal and mechanical properties. They have been expected to be the main candidates for applications such as turbocharger rotors and gas turbine engine components which can withstand severe conditions of temperature and heavy loads. Although a big number of studies on silicon nitride are published, a continuous progress in monolithic Si 3 N 4 as well as Si 3 N 4 /Si 3 N 4 composites (seeded materials) leads to new scientific and technological data providing new insight that should be reviewed taking into account their excellent properties at high temperatures. Silicon nitride possesses a bunch variety of interesting properties that can be specifically designed to produce a given behavior profile. That is why the room temperature and high-temperature properties are discussed and described in more detail.

Performance enhancement of terahertz metamaterials on ultrathin substrates for sensing applications

Abstract: We design, fabricate, and characterize split-ring resonator (SRR) based planar terahertz metamaterials (MMs) on ultrathin silicon nitride substrates for biosensing applications. Proof-of-principle demonstration of increased sensitivity in thin substrate SRR-MMs is shown by detection of doped and undoped protein thin films (silk fibroin) of various thicknesses and by monitoring transmission changes using terahertz time-domain spectroscopy. SRR-MMs fabricated on thin film substrates show significantly better performance than identical SRR-MMs fabricated on bulk silicon substrates paving the way for improved biological and chemical sensing applications.

Silicon nitride gate dielectrics and band gap engineering in graphene layers.

Abstract: We show that silicon nitride can provide uniform coverage of graphene in field-effect transistors while preserving the channel mobility. This insulator allowed us to study the maximum channel resistance at the Dirac (neutrality) point as a function of the strength of a perpendicular electric field in top-gated devices with different numbers of graphene layers. Using a simple model to account for surface potential variations (electron-hole puddles) near the Dirac point we estimate the field-induced band gap or band overlap in the different layers.

Group velocity dispersion and self phase modulation in silicon nitride waveguides

Abstract: The group velocity dispersion (GVD) of silicon nitride waveguides, prepared using plasma enhanced chemical vapor deposition, is studied and characterized experimentally in support of nonlinear optics applications We show that the dispersion may be engineered by varying the geometry of the waveguide and demonstrate measured anomalous GVD values as high as −057 ps2/m and normal GVD values as high as 086 ps2/m We also experimentally demonstrate the absence of any observed nonlinear loss at the telecommunications wavelength at peak intensities of up to 12 GW/cm2 Spectral broadening due to self phase modulation in silicon nitride waveguides with a nonlinear parameter of 14 W−1/m is also demonstrated

Wide Bandwidth Silicon Nitride Grating Coupler

Abstract: We demonstrate a one-dimensional grating coupler in silicon nitride with a 67-nm 1-dB bandwidth, the largest reported for a grating coupler butt-coupled to standard single-mode fiber. The peak coupling efficiency is -4.2dB. It requires no partial etch and requires only 0.6-μm fabrication resolution.

Low K dielectric surface damage control

Abstract: A method of removing a silicon nitride or a nitride-based bottom etch stop layer in a copper damascene structure by etching the bottom etch stop layer is disclosed, with the method using a high density, high radical concentration plasma containing fluorine and oxygen to minimize back sputtering of copper underlying the bottom etch stop layer and surface roughening of the low-k interlayer dielectric caused by the plasma.

Dry etching method for silicon nitride film

Abstract: A dry etching method for a silicon nitride film capable of improving throughput is provided. A dry etching method for dry-etching a silicon nitride film 103 includes dry-etching the silicon nitride film 103 without generating plasma by using a processing gas containing at least a hydrogen fluoride gas (HF gas) and a fluorine gas (F2 gas), with respect to a processing target object 100 including the silicon nitride film 103.

Silicon nitride gate dielectrics and bandgap engineering in graphene layers

Abstract: We show that silicon nitride can provide uniform coverage of graphene in field-effect transistors while preserving the channel mobility. This insulator allowed us to study the maximum channel resistance at the Dirac (neutrality) point as a function of the strength of a perpendicular electric field in top-gated devices with different numbers of graphene layers. Using a simple model to account for surface potential variations (electron-hole puddles) near the Dirac point we estimate the field-induced band-gap or band-overlap in the different layers.

Growth of One‐Dimensional Nanostructures in Porous Polymer‐Derived Ceramics by Catalyst‐Assisted Pyrolysis. Part I: Iron Catalyst

Abstract: Via catalyst-assisted pyrolysis, Si3N4 and SiC nanowires were produced on the cell walls of polymer-derived ceramic foams. The pyrolysis atmosphere and temperature were the main parameters affecting their development: silicon nitride single-crystal nanowires formed under nitrogen, while silicon carbide ones were produced under argon, and their amount increased with the increasing pyrolysis temperature. Brunauer–Emmett–Teller analysis showed that the presence of the nanowires afforded high specific surface area (SSA) values to the macroporous ceramic foams, ranging from 10 to 110 m2/g. Co-containing samples developed higher SSA values, especially after pyrolysis at 1400°C in N2, than samples containing Fe as a catalyst. The differences were explained in terms of morphology (diameter and assemblage), which depended on the processing conditions and the catalyst type (Co or Fe).

Reducing quantum-regime dielectric loss of silicon nitride for superconducting quantum circuits

Abstract: The loss of amorphous hydrogenated silicon nitride (a-SiNx:H) is measured at 30 mK and 5 GHz using a superconducting LC resonator down to energies where a single-photon is stored, and analyzed with an independent two-level system defect model. Each a-SiNx:H film was deposited with different concentrations of hydrogen impurities. We find that quantum-regime dielectric loss tangent tan δ0 in a-SiNx:H is strongly correlated with N–H impurities, including NH2. By slightly reducing x we are able to reduce tan δ0 by approximately a factor of 50, where the best films show tan δ0≃3×10−5.

Carbon Nanotubes as a Framework for High-Aspect-Ratio MEMS Fabrication

Abstract: A class of carbon-nanotube (CNT) composite materials was developed to take advantage of the precise high-aspect-ratio shape of patterned vertically grown nanotube forests. These patterned forests were rendered mechanically robust by chemical vapor infiltration and released by etching an underlying sacrificial layer. We fabricated a diverse variety of functional MEMS devices, including cantilevers, bistable mechanisms, and thermomechanical actuators, using this technique. A wide range of chemical-vapor-depositable materials could be used as fillers; here, we specifically explored infiltration by silicon and silicon nitride. The CNT framework technique may enable high-aspect-ratio MEMS fabrication from a variety of materials with desired properties such as high-temperature stability or robustness. The elastic modulus of the silicon-nanotube and silicon nitride-nanotube composites is dominated by the filler material, but they remain electrically conductive, even when the filler (over 99% of the composite's mass) is insulating.

ZnO nanowires grown on SOI CMOS substrate for ethanol sensing

Abstract: This paper reports on the integration of zinc oxide nanowires (ZnO NWs) with a silicon on insulator (SOI) CMOS (complementary metal oxide semiconductor) micro-hotplate for use as an alcohol sensor. The micro-hotplates consist of a silicon resistive micro-heater embedded within a membrane (composed of silicon oxide and silicon nitride, supported on a silicon substrate) and gold bump bonded aluminum electrodes that are used to make an ohmic contact with the sensing material. ZnO NWs were grown by a simple, low-cost hydrothermal method and characterised using SEM, XRD and photoluminiscence methods. The chemical sensitivity of the on-chip NWs to ethanol vapour (at different humidity levels) was characterised at two different temperatures namely, 300 °C and 400 °C (power consumption was 24 mW and 33 mW, respectively), and the sensitivity was found to be 0.1%/ppm (response 4.7 at 4363 ppm). These results show that ZnO NWs are a promising material for use as a CMOS ethanol gas sensor that offers low cost, low power consumption and integrated circuitry.

A MEMS Reactor for Atomic-Scale Microscopy of Nanomaterials Under Industrially Relevant Conditions

Abstract: We present a microelectromechanical systems (MEMS) nanoreactor that enables high-resolution transmission electron microscopy (TEM) (HRTEM) of nanostructured materials with atomic-scale resolution during exposure to reactive gases at 1 atm of pressure. This pressure exceeds that of existing HRTEM systems by a factor of 100, thereby entering a pressure range that is relevant to industrial purposes. The nanoreactor integrates a shallow flow channel (35 ?m high) with a microheater and with an array of electron transparent windows of silicon nitride. The windows are only 10 nm thick but are mechanically robust. The heater has the geometry of a microhotplate and is made of Pt embedded in a silicon nitride membrane. To interface the nanoreactor, a dedicated TEM specimen holder has been developed. The performance is demonstrated by the live formation of Cu nanoparticles in a catalyst for the production of methanol. At 120 kPa and for temperatures of up to 500°C , the formation of these nanoparticles can be observed clearly and with an exceptionally low thermal drift. HRTEM images of the nanoparticles show atomic lattice fringes with spacings down to 0.18 nm.

Spark plasma sintering: A powerful tool to develop new silicon nitride-based materials

Abstract: Several key topics on the current assisted sintering of Si3N4-based materials are reviewed. First, different proposed mechanisms for spark plasma sintered (SPSed) ceramics are presented, discussing the electric field effect on the liquid phase behaviour and how it may influence the liquid phase sintering of Si3N4 ceramics. Next, we show that the SPS is a powerful tool to develop new Si3N4-based materials with tailored microstructures, such as functionally graded materials (FGMs) and carbon nanotubes (CNTs) containing Si3N4 matrix composites. Si3N4 FGMs are fabricated from a sole homogenous Si3N4 mixture just modifying the SPS system punches set-up, thus creating a temperature gradient through the specimen. Finally, the capability of SPS to get dense Si3N4/CNTs composites overcoming both constraint densification and nanotubes degradation is proved.

Investigation of the interface between silicon nitride passivations and AlGaN/AlN/GaN heterostructures by C"V… characterization of metal-insulator-semiconductor-heterostructure capacitors

Abstract: Capacitance-voltage [C(V)] measurements of metal-insulator-semiconductor-heterostructure capacitors are used to investigate the interface between silicon nitride passivation and AlGaN/AlN/GaN heterostructure material. AlGaN/AlN/GaN samples having different silicon nitride passivating layers, deposited using three different deposition techniques, are evaluated. Different interface state distributions result in large differences in the C(V) characteristics. A method to extract fixed charge as well as traps from the C(V) characteristics is presented. Rough estimates of the emission time constants of the traps can be extracted by careful analysis of the C(V) characteristics. The fixed charge is positive for all samples, with a density varying between 1.3 x 10(12) and 7.1 x 10(12) cm(-2). For the traps, the peak density of interface states is varying between 16 x 10(12) and 31 x 10(12) cm(-2) eV(-1) for the three samples. It is concluded that, of the deposition methods investigated in this report, the low pressure chemical vapor deposited silicon nitride passivation shows the most promising results with regards to low densities of interface states. (C) 2010 American Institute of Physics. [doi:10.1063/1.3428442]

Electroluminescence from Er-doped Si-rich silicon nitride light emitting diodes

Abstract: Electrical devices based on Erbium (Er) doping of silicon nitride have been fabricated by reactive cosputtering and intense, room temperature Er electroluminescence was observed in the visible (527, 550, and 660 nm) and near-infrared (980 and 1535 nm) spectral ranges at low injection voltages (<5 V EL turn on). The electrical transport mechanism in these devices was investigated and the excitation cross section for the 1535 nm Er emission was measured under electrical pumping, resulting in a value (1.2×10−15 cm2) comparable to optical pumping. These results indicate that Er-doped silicon nitride has a large potential for the engineering of light sources compatible with Si technology.

Light-emitting diode

Abstract: The invention relates to a light emitting diode. The light emitting diode comprises a mono-crystalline substrate, a buffer layer, a transition layer, an N-type semiconductor layer, an active layer, a P-type semiconductor layer, a P-type contact layer and a P-type electrode sequentially formed on the mono-crystalline substrate, and an N-type electrode arranged on the N-type semiconductor layer, wherein the buffer layer which is formed by combining two or more of silicon, silicon dioxide, silicon nitride, titanium dioxide, zinc oxide, gallium nitride, sapphire and silicon carbide material is arranged between the mono-crystalline substrate and the transition layer; and the buffer layer close to the transition layer is made of one of gallium nitride, sapphire and silicon carbide material. Compared with the conventional structure, the structure of the light emitting diode can improve the heat dissipation of the light emitting diode, has a simple structure, is convenient to manufacture and reduces the production cost.

Preventing nanoscale wear of atomic force microscopy tips through the use of monolithic ultrananocrystalline diamond probes.

Abstract: Nanoscale wear is a key limitation of conventional atomic force microscopy (AFM) probes that results in decreased resolution, accuracy, and reproducibility in probe-based imaging, writing, measurement, and nanomanufacturing applications. Diamond is potentially an ideal probe material due to its unrivaled hardness and stiffness, its low friction and wear, and its chemical inertness. However, the manufacture of monolithic diamond probes with consistently shaped small-radius tips has not been previously achieved. The first wafer-level fabrication of monolithic ultrananocrystalline diamond (UNCD) probes with <5-nm grain sizes and smooth tips with radii of 30-40 nm is reported, which are obtained through a combination of microfabrication and hot-filament chemical vapor deposition. Their nanoscale wear resistance under contact-mode scanning conditions is compared with that of conventional silicon nitride (SiN{sub x}) probes of similar geometry at two different relative humidity levels ({approx}15 and {approx}70%). While SiN{sub x} probes exhibit significant wear that further increases with humidity, UNCD probes show little measurable wear. The only significant degradation of the UNCD probes observed in one case is associated with removal of the initial seed layer of the UNCD film. The results show the potential of a new material for AFM probes and demonstrate a systematic approach to studying wearmore » at the nanoscale.« less

Fabrication of Metallized Nanopores in Silicon Nitride Membranes for Single-Molecule Sensing

Abstract: The fabrication and characterization of a metallized nanopore structure for the sensing of single molecules is described. Pores of varying diameters (>10 nm) are patterned into free-standing silicon nitride membranes by electron-beam lithography and reactive ion etching. Structural characterization by transmission electron microscopy (TEM) and tomography reveals a conical pore shape with a 40 degrees aperture. Metal films of Ti/Au are vapor deposited and the pore shape and shrinking are studied as a function of evaporated film thickness. TEM tomography analysis confirms metalization of the inner pore walls as well as conservation of the conical pore shape. In electrical measurements of the transpore current in aqueous electrolyte solution, the pores feature very low noise. The applicability of the metallized pores for stochastic sensing is demonstrated in real-time translocation experiments of single lambda-DNA molecules. We observe exceptionally long-lasting current blockades with a fine structure of distinct current levels, suggesting an attractive interaction between the DNA and the PEGylated metallic pore walls.

The influence of SiOx and SiNx passivation on the negative bias stability of Hf-In-Zn-O thin film transistors under illumination

Abstract: The stability of hafnium indium zinc oxide thin film transistors under negative bias stress with simultaneous exposure to white light was evaluated. Two different inverted staggered bottom gate devices, each with a silicon oxide and a silicon nitride passivation, were compared. The latter exhibits higher field effect mobility but inferior subthreshold swing, and undergoes more severe shifts in threshold voltage (VT) during negative bias illumination stress. The time evolution of VT fits the stretched exponential equation, which implies that hydrogen incorporation during the nitride growth has generated bulk defects within the semiconductor and/or at the semiconductor/gate dielectric interface.

Method and device for etching silicon nitride

Abstract: PROBLEM TO BE SOLVED: To etch a silicon nitride film at high speed and to suppress etching of a substrate of silicon nitride while preventing thermal damage to an object to be processed formed by coating the substrate with the silicon nitride film to be etched. SOLUTION: A processing gas including hydrogen fluoride and water is brought into contact with the object 90 to be processed to carry out etching. The etching includes two steps of a first etching step and a second etching step. In the first etching step, the object 90 to be processed is held substantially at room temperature, or preferably at 20 to 30°C. In the second etching step, the object 90 to be processed is held at 50 to 130°C, preferably at 60 to 110°C, or more preferably at 70 to 100°C. COPYRIGHT: (C)2011,JPO&INPIT

Ultrathin silicon nitride microring resonator for biophotonic applications at 970 nm wavelength

Abstract: We experimentally demonstrate a high-Q ultrathin silicon nitride microring resonator operating at wavelength of 970 nm that is favorable for large variety of biophotonic applications. Implementation of thin device layer of 200 nm allows enhanced interaction between the optical mode and environment, while still maintaining high quality factor of resonator. In addition, we show the importance of spectral window around 970 nm to improve device sensing capability.