Showing papers on "Silicon nitride published in 2009"

High confinement micron-scale silicon nitride high Q ring resonator

Abstract: We demonstrate high confinement, low-loss silicon nitride ring resonators with intrinsic quality factor (Q) of 3∗106 operating in the telecommunication C-band. We measure the scattering and absorption losses to be below 0.065dB/cm and 0.055dB/cm, respectively.

A novel fiber-reinforced polyethylene composite with added silicon nitride particles for enhanced thermal conductivity

Abstract: A novel thermally conductive plastic composite was prepared from a mixture of silicon nitride (Si 3 N 4 ) filler particles and an ultrahigh molecular weight polyethylene–linear low density polyethylene blend. The effects of Si 3 N 4 particle sizes, concentration, and dispersion on the thermal conductivity and relevant dielectric properties were investigated. With proper fabrication the Si 3 N 4 particles could form a continuously connected dispersion that acted as the dominant thermally conductive pathway through the plastic matrix. By adding 0–20% Si 3 N 4 filler particles, the composite thermal conductivity was increased from 0.2 to ∼1.0 W m −1 K −1 . Also, the composite thermal conductivity was further enhanced to 1.8 W m −1 K −1 by decreasing the Si 3 N 4 particle sizes from 35, 3 and 0.2 μm, and using coupling agent, for the composites with higher filler content. Alumina short fibers were then added to improve the overall composite toughness and strength. Optimum thermal, dielectric and mechanical properties were obtained for a fiber-reinforced polyethylene composite with 20% total alumina–Si 3 N 4 (0.2 μm size) filler particles.

Low temperature deposition of silicon-containing films

Abstract: This invention discloses the method of forming silicon nitride, silicon oxynitride, silicon oxide, carbon-doped silicon nitride, carbon-doped silicon oxide and carbon-doped oxynitride films at low deposition temperatures. The silicon containing precursors used for the deposition are monochlorosilane (MCS) and monochloroalkylsilanes. The method is preferably carried out by using plasma enhanced atomic layer deposition, plasma enhanced chemical vapor deposition, and plasma enhanced cyclic chemical vapor deposition.

Joining of engineering ceramics

Abstract: Engineering ceramics such as alumina, zirconia, silicon nitride and silicon carbide can now be manufactured reliably with reproducible properties As such, they are of increasing interest to industry, particularly for use in demanding environments, where their thermomechanical performance is of critical importance, with applications ranging from fuel cells to cutting tools One aspect common to virtually all applications of engineering ceramics is that eventually they must be joined with another material, most usually a metal The joining of engineering ceramics to metals is not always easy There are two main considerations The first consideration is the basic difference in atomic bonding: the ionic or covalent bonding of the ceramic, compared to the metallic bond The second consideration is the mismatch in the coefficient of thermal expansion In general, ceramics have a lower coefficient of thermal expansion than metals and, if high tensile forces are produced in the ceramic, either a

Microstructure and mechanical properties of Ni–P coated Si3N4 reinforced Al6061 composites

Abstract: Silicon nitride is currently a popular choice as reinforcement to develop light alloy composites owing to its high hot hardness and excellent wear and corrosion resistance. However, meager information is available as regards the development of aluminum alloy–silicon nitride composites by stir cast technique. This route of processing metal matrix composites (MMCs) poses challenges in particular, poor wettability of the ceramic reinforcement in the matrix alloy. To overcome this problem, researchers are currently focusing on use of metallic coated ceramic reinforcement. In the light of the above, this paper discusses the development of Ni–P coated silicon nitride reinforced Al6061 composites by stir cast method. XRD, metallographic, EDAX studies, microhardness, and tensile strength tests of the developed composites have been carried out. A maximum of 10 wt% of Ni–P coated silicon nitride has been dispersed uniformly in the matrix alloy. A drastic improvement in both microhardness and tensile strength is observed.

Methods for forming silicon nitride based film or silicon carbon based film

Abstract: A method for depositing a silicon nitride based dielectric layer is provided The method includes introducing a silicon precursor and a radical nitrogen precursor to a deposition chamber The silicon precursor has a N-Si-H bond, N-Si-Si bond and/or Si-Si-H bond The radical nitrogen precursor is substantially free from included oxygen The radical nitrogen precursor is generated outside the deposition chamber The silicon precursor and the radical nitrogen precursor interact to form the silicon nitride based dielectric layer

Effective surface passivation of crystalline silicon using ultrathin Al2O3 films and Al2O3/SiNx stacks

Abstract: We measure surface recombination velocities (SRVs) below 10 cm/s on p-type crystalline silicon wafers passivated by atomic–layer–deposited (ALD) aluminium oxide (Al2O3) films of thickness ≥10 nm. For films thinner than 10 nm the SRV increases with decreasing Al2O3 thickness. For ultrathin Al2O3 layers of 3.6 nm we still attain a SRV < 22 cm/s on 1.5 Ω cm p-Si and an exceptionally low SRV of 1.8 cm/s on high-resistivity (200 Ω cm) p-Si. Ultrathin Al2O3 films are particularly relevant for the implementation into solar cells, as the deposition rate of the ALD process is extremely low compared to the frequently used plasma-enhanced chemical vapour deposition of silicon nitride (SiNx). Our experiments on silicon wafers passivated with stacks composed of ultrathin Al2O3 and SiNx show that a substantially improved thermal stability during high-temperature firing at 830 °C is obtained for the Al2O3/SiNx stacks compared to the single-layer Al2O3 passivation. Al2O3/SiNx stacks are hence ideally suited for the implementation into industrial-type silicon solar cells where the metal contacts are made by screen-printing and high-temperature firing of metal pastes. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Stress management for tensile films

Abstract: The formation of a gap-filling silicon oxide layer with reduced tendency towards cracking is described. The deposition involves the formation of a flowable silicon-containing layer which facilitates the filling of trenches. Subsequent processing at high substrate temperature causes less cracking in the dielectric film than flowable films formed in accordance with methods in the prior art. A compressive liner layer deposited prior to the formation of the gap-filling silicon oxide layer is described and reduces the tendency for the subsequently deposited film to crack. A compressive capping layer deposited after a flowable silicon-containing layer has also been determined to reduce cracking. Compressive liner layers and compressive capping layers can be used alone or in combination to reduce and often eliminate cracking. Compressive capping layers in disclosed embodiments have additionally been determined to enable an underlying layer of silicon nitride to be transformed into a silicon oxide layer.

Low temperature thin film transistor process, device property, and device stability improvement

Abstract: A method and apparatus for forming a thin film transistor is provided. A gate dielectric layer is formed, which may be a bilayer, the first layer deposited at a low rate and the second deposited at a high rate. In some embodiments, the first dielectric layer is a silicon rich silicon nitride layer. An active layer is formed, which may also be a bilayer, the first active layer deposited at a low rate and the second at a high rate. The thin film transistors described herein have superior mobility and stability under stress.

Amorphous In–Ga–Zn–O coplanar homojunction thin-film transistor

Abstract: A fabrication process of coplanar homojunction thin-film transistors (TFTs) is proposed for amorphous In–Ga–Zn–O (a-IGZO), which employs highly doped contact regions naturally formed by deposition of upper protection layers made of hydrogenated silicon nitride (SiNX:H). The direct deposition of SiNX:H reduced the resistivity of the semiconductive a-IGZO layer down to 6.2×10−3 Ω cm and formed a nearly ideal Ohmic contact with a low parasitic source-to-drain resistance of 34 Ω cm. Simple evaluation of field-effect mobilities (μsat) overestimated their values especially for short-channel TFTs, while the channel resistance method proved that μsat was almost constant at 9.5 cm2 V−1 s−1.

High quality planar silicon nitride microdisk resonators for integrated photonics in the visible wavelength range.

Abstract: High quality factor (Q approximately 3.4 x 10(6)) microdisk resonators are demonstrated in a Si(3)N(4) on SiO(2) platform at 652-660 nm with integrated in-plane coupling waveguides. Critical coupling to several radial modes is demonstrated using a rib-like structure with a thin Si(3)N(4) layer at the air-substrate interface to improve the coupling.

Size-dependent effective Young’s modulus of silicon nitride cantilevers

Abstract: The effective Young’s modulus of silicon nitride cantilevers is determined for thicknesses in the range of 20–684 nm by measuring resonance frequencies from thermal noise spectra. A significant deviation from the bulk value is observed for cantilevers thinner than 150 nm. To explain the observations we have compared the thickness dependence of the effective Young’s modulus for the first and second flexural resonance mode and measured the static curvature profiles of the cantilevers. We conclude that surface stress cannot explain the observed behavior. A surface elasticity model fits the experimental data consistently.

Nonvolatile semiconductor memory device and method for manufacturing the same

Abstract: On a silicon substrate is formed a stacked body by alternately stacking a plurality of silicon oxide films and silicon films, a trench is formed in the stacked body, an alumina film, a silicon nitride film and a silicon oxide film are formed in this order on an inner surface of the trench, and a channel silicon crystalline film is formed on the silicon oxide film. Next, a silicon oxide layer is formed at an interface between the silicon oxide film and the channel silicon crystalline film by performing thermal treatment in an oxygen gas atmosphere.

Temperature distribution for electrically conductive and non-conductive materials during Field Assisted Sintering (FAST)

Abstract: During Field Assisted Sintering Technology (FAST) the temperature differences at two different positions were investigated using two pyrometers, an internal and an external one. Two substances, an electrically conductive (tungsten carbide) and a non-conductive material (96 wt.% silicon nitride with 2 wt.% alumina and yttria) were used to monitor the temperature differences between both pyrometers during heating, sintering shrinkage and dwell time by varying die geometry and heating rate. It was shown that the temperature distribution is strongly influenced by the electrical conductivity of the material as well as by tool design and setup. The alpha–beta transformation of silicon nitride was analyzed to predict the radial temperature distribution within the sample. For comparison and for visualization a dynamical FE model including piston movement for simulating sintering shrinkage was introduced. With this, a complete time dependent FAST run could be simulated. The modeled differences in temperature distribution are in good agreement with real temperature measurements as well as phase analyses.

Varied silicon richness silicon nitride formation

Abstract: A method, in one embodiment, can include forming a tunnel oxide layer on a substrate. In addition, the method can include depositing via atomic layer deposition a first layer of silicon nitride over the tunnel oxide layer. Note that the first layer of silicon nitride includes a first silicon richness. The method can also include depositing via atomic layer deposition a second layer of silicon nitride over the first layer of silicon nitride. The second layer of silicon nitride includes a second silicon richness that is different than the first silicon richness.

Covalently Attached Organic Monolayers on SiC and SixN4 Surfaces: Formation Using UV Light at Room Temperature

Abstract: We describe the formation of alkyl monolayers on silicon carbide (SiC) and silicon-rich silicon nitride (SixN4) surfaces, using UV irradiation in the presence of alkenes. Both the surface preparation and the monolayer attachment were carried out under ambient conditions. The stable coatings obtained in this way were studied by water contact angle measurements, infrared reflection absorption spectroscopy, X-ray reflectivity, and X-ray photoelectron spectroscopy. Besides unfunctionalized 1-alkenes, methyl undec-10-enoate, and 2,2,2-trifluoroethyl undec-10-enoate were also grafted onto both substrates. The resulting ester-terminated surfaces could then be further reacted after hydrolysis using amide chemistry to easily allow the attachment of amine-containing compounds.

Selective Laser Ablation of SiNx Layers on Textured Surfaces for Low Temperature Front Side Metallizations

Abstract: For an alternative front side metallization process without screen printing of metal paste the selective opening of the front surface anti-reflection coating could be realized by laser ablation. A successful implementation of this scheme requires direct absorption of the laser light within the anti-reflection coating, since the emitter underneath must not be damaged severely. Additionally, the ablation must be feasible on textured surfaces. In this paper, we show that laser light with a wavelength of 355 nm and a pulse length of approximately 30 ns is absorbed directly by a typical silicon nitride anti-reflection coating. Based on lifetime measurements on ablated samples it is shown that a damage free laser ablation of SiNx layers on planar surfaces is possible. The characteristic ablation structure on textured surfaces is explained and quantified by rigorous coupled wave analysis (RCWA) simulations. Finally, high efficiency solar cells with a standard emitter (Rsh approx. 50 Ω/sq) have been processed using laser ablation of the silicon nitride anti-reflection coating. These cells show efficiencies of up to 19·1%, comparable to the reference solar cells using photolithographically opened contact areas. Copyright © 2008 John Wiley & Sons, Ltd.

Polishing liquid and polishing method

Abstract: A polishing liquid which is used for chemical mechanical polishing of a body to be polished in a planarization process for manufacturing of a semiconductor integrated circuit, the body to be polished including at least a first layer containing polysilicon or modified polysilicon and a second layer containing at least one selected from the group consisting of silicon oxide, silicon nitride, silicon carbide, silicon carbonitride, silicon oxycarbide, and silicon oxynitride, the polishing liquid having a pH of 1.5 to 7.0, including (1) colloidal silica particles, (2) an organic acid, and (3) an anionic surfactant, and being capable of selectively polishing the second layer with respect to the first layer.

Thermal conductivity of micromachined low-stress silicon-nitride beams from 77 to 325 K

Abstract: We present thermal conductivity measurements of micromachined 500 nm thick silicon-nitride (Si–N) beams suspended between two Si–N islands, in the temperature range from 77 to 325 K. The measured thermal conductivity, k, of Si–N at high temperatures is in good agreement with previously measured values for Si–N grown by low-pressure chemical vapor deposition, but behaves much differently as temperature is lowered, showing a dependence more similar to polycrystalline materials. Preliminary structural characterization by x-ray diffraction suggests that the material is likely nano- or polycrystalline. The micromachined suspended platform structure is designed to allow highly accurate measurements of the thermal conductivity of deposited metallic, semiconducting, or insulating thin films. As a demonstration, we present measurements of a 200 nm thick sputtered molybdenum film. In the entire temperature range the measured thermal conductivity matches the prediction of the Wiedemann–Franz thermal conductivity det...

Method for manufacturing a semiconductor integrated circuit device circuit device

Abstract: When a natural oxide film is left at the interface between a metal silicide layer and a silicon nitride film, in various heating steps (steps involving heating of a semiconductor substrate, such as various insulation film and conductive film deposition steps) after deposition of the silicon nitride film, the metal silicide layer partially abnormally grows due to oxygen of the natural oxide film occurring on the metal silicide layer surface. A substantially non-bias (including low bias) plasma treatment is performed in a gas atmosphere containing an inert gas as a main component on the top surface of a metal silicide film of nickel silicide or the like over source/drain of a field-effect transistor forming an integrated circuit. Then, a silicon nitride film serving as an etching stop film of a contact process is deposited. As a result, without causing undesirable cutting of the metal silicide film, the natural oxide film over the top surface of the metal silicide film can be removed.

Method of manufacturing semiconductor device

Abstract: In a semiconductor device manufacturing method of the present invention, a polysilicon film and a silicon nitride film are deposited on an upper surface of an epitaxial layer Patterning is performed so that the polysilicon film and the silicon nitride film are left in regions in which a LOCOS oxide film is to be formed Then, using steps of the polysilicon film and the silicon nitride film as alignment marks, a diffusion layer as drain regions is formed Subsequently, the LOCOS oxide film is formed This manufacturing method enables the diffusion layer to be formed with high position accuracy without being affected by a shape of the LOCOS oxide film

Thin film nanocalorimeter for heat capacity measurements of 30 nm films

Abstract: A silicon nitride membrane-based nanocalorimeter is described for measuring the heat capacity of 30 nm films from 300 mK to 800 K and in high magnetic fields with absolute accuracy approximately 2%. The addenda heat capacity of the nanocalorimeter is less than 2 x 10(-7) J/K at room temperature and 2 x 10(-10) J/K at 2.3 K. This is more than ten times smaller than any existing calorimeter suitable for measuring thin films over this wide temperature range. The heat capacities of thin Cu and Au films are reported and agree with bulk values. The thermal conductivity of the thin low stress silicon nitride is substantially smaller than thicker membranes while the specific heat is enhanced below 20 K. Design of the nanocalorimeter will be discussed along with fabrication details and calibration results.

Various shapes of silicon freestanding microfluidic channels and microstructures in one-step lithography

Abstract: In this research, we have developed and demonstrated a fabrication method for the formation of various shapes of silicon freestanding microfluidic channels and microstructures in one-step photolithography. The fabrication process utilizes the silicon direct wafer bonding with silicon nitride as an intermediate layer, local oxidation of the silicon (LOCOS) process and wet anisotropic etching. Two different types of etchants (non-ionic surfactant (Triton-X-100) added and pure 25 wt% TMAH solutions) are used in series to perform silicon anisotropic etching. Surfactant-added tetramethyl ammonium hydroxide (TMAH) is employed to define the shapes of the structures, while pure TMAH is used to get high undercutting for their fast releasing. The non-ionic surfactant is preferred considering the complementary metal-oxide semiconductor (CMOS) post process issue of wet anisotropic etching. The undercutting at sharp and rounded concave corners, edges aligned along 1 0 0 directions, is measured and analyzed in both pure and surfactant-added TMAH solutions. Mask design issues that must be taken into consideration for the fabrication of desired shape and size structures are also presented.