Showing papers on "Silicon nitride published in 2014"

Low temperature gas-phase carbon removal

Abstract: A method of etching carbon films on patterned heterogeneous structures is described and includes a gas phase etch using remote plasma excitation. The remote plasma excites a fluorine-containing precursor and an oxygen-containing precursor, the plasma effluents created are flowed into a substrate processing region. The plasma effluents etch the carbon film more rapidly than silicon, silicon nitride, silicon carbide, silicon carbon nitride and silicon oxide.

Post-Deposition Treatment Methods For Silicon Nitride

Abstract: Provided are methods post deposition treatment of films comprising SiN. Certain methods pertain to providing a film comprising SiN; and exposing the film to an inductively coupled plasma, capacitively coupled plasma or a microwave plasma to provide a treated film with a modulated film stress and/or wet etch rate in dilute HF. Certain other methods comprise depositing a PEALD SiN film followed by exposure to a plasma nitridation process or a UV treatment to provide a treated film.

Selective etch of silicon nitride

Abstract: A method of etching silicon nitride on patterned heterogeneous structures is described and includes a remote plasma etch formed from a fluorine-containing precursor and a nitrogen-and-oxygen-containing precursor. Plasma effluents from two remote plasmas are flowed into a substrate processing region where the plasma effluents react with the silicon nitride. The plasmas effluents react with the patterned heterogeneous structures to selectively remove silicon nitride while very slowly removing silicon, such as polysilicon. The silicon nitride selectivity results partly from the introduction of fluorine-containing precursor and nitrogen-and-oxygen-containing precursor using distinct (but possibly overlapping) plasma pathways which may be in series or in parallel.

Silicide protection during contact metallization and resulting semiconductor structures

Abstract: A semiconductor transistor has a structure including a semiconductor substrate, a source region, a drain region and a channel region in between the source region and the drain region. A metal gate, having a top conductive portion of tungsten is provided above the channel region. A first silicon nitride protective layer over the source region and the drain region and a second silicon nitride protective layer over the gate region are provided. The first silicon nitride protective layer and the second silicon nitride protective layer are configured to allow punch-through of the first silicon nitride protective layer while preventing etching through the second silicon nitride protective layer. Source and drain silicide is protected by avoiding fully etching a gate opening unless either the etching used would not harm the silicide, or the silicide and source and drain contacts are created prior to fully etching an opening to the gate for a gate contact.

Excellent c-Si surface passivation by low-temperature atomic layer deposited titanium oxide

Abstract: In this work, we demonstrate that thermal atomic layer deposited (ALD) titanium oxide (TiOx) films are able to provide a—up to now unprecedented—level of surface passivation on undiffused low-resistivity crystalline silicon (c-Si). The surface passivation provided by the ALD TiOx films is activated by a post-deposition anneal and subsequent light soaking treatment. Ultralow effective surface recombination velocities down to 2.8 cm/s and 8.3 cm/s, respectively, are achieved on n-type and p-type float-zone c-Si wafers. Detailed analysis confirms that the TiOx films are nearly stoichiometric, have no significant level of contaminants, and are of amorphous nature. The passivation is found to be stable after storage in the dark for eight months. These results demonstrate that TiOx films are also capable of providing excellent passivation of undiffused c-Si surfaces on a comparable level to thermal silicon oxide, silicon nitride, and aluminum oxide. In addition, it is well known that TiOx has an optimal refractive index of 2.4 in the visible range for glass encapsulated solar cells, as well as a low extinction coefficient. Thus, the results presented in this work could facilitate the re-emergence of TiOx in the field of high-efficiency silicon wafer solar cells.

Low-Loss Silicon Nitride AWG Demultiplexer Heterogeneously Integrated With Hybrid III–V/Silicon Photodetectors

Abstract: A unique and novel platform that combines III-V and silicon photonic components with ultra-low loss silicon nitride waveguides for monolithic integration of novel photonic circuits is presented. Successful (proof-of-principle) integration of eight hybrid III-V/silicon photodetectors and an arrayed waveguide grating is shown. The InGaAs photodiodes in this platform had average fiber-coupled responsivity of 0.36 A/W at 1550 nm, 30 GHz electrical bandwidth, and operated up to 50 Gb/s. The AWG had an insertion loss of 0.85 dB and adjacent-channel cross-talk less than -38 dB.

Plasma atomic layer deposition

Abstract: Plasma atomic layer deposition (ALD) is optimized through modulation of the gas residence time during an excited species phase, wherein activated reactant is supplied such as from a plasma. Reduced residence time increases the quality of the deposited layer, such as reducing wet etch rates, increasing index of refraction and/or reducing impurities in the layer. For example, dielectric layers, particularly silicon nitride films, formed from such optimized plasma ALD processes have low levels of impurities remaining from the silicon precursor.

Method of patterning a silicon nitride dielectric film

Abstract: Methods of patterning silicon nitride dielectric films are described. For example, a method of isotropically etching a dielectric film involves partially modifying exposed regions of a silicon nitride layer with an oxygen-based plasma process to provide a modified portion and an unmodified portion of the silicon nitride layer. The method also involves removing, selective to the unmodified portion, the modified portion of the silicon nitride layer with a second plasma process.

Titanium oxide etch

Abstract: Methods of selectively etching titanium oxide relative to silicon oxide, silicon nitride and/or other dielectrics are described. The methods include a remote plasma etch using plasma effluents formed from a fluorine-containing precursor and/or a chlorine-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the titanium oxide. The plasmas effluents react with exposed surfaces and selectively remove titanium oxide while very slowly removing other exposed materials. A direction sputtering pretreatment is performed prior to the remote plasma etch and enables an increased selectivity as well as a directional selectivity. In some embodiments, the titanium oxide etch selectivity results partly from the presence of an ion suppression element positioned between the remote plasma and the substrate processing region.

Plasma-free metal etch

Abstract: Methods of selectively etching metal-containing materials from the surface of a substrate are described. The etch selectively removes metal-containing materials relative to silicon-containing films such as silicon, polysilicon, silicon oxide, silicon germanium, silicon carbide, silicon carbon nitride and/or silicon nitride. The methods include exposing metal-containing materials to halogen containing species in a substrate processing region. No plasma excites the halogen-containing precursor either remotely or locally in embodiments.

Integrated oxide and nitride recess for better channel contact in 3D architectures

Abstract: Methods of etching back an oxide-nitride-oxide (ONO) layer of a 3-d flash memory cell without breaking vacuum are described. The methods include recessing the two outer silicon oxide dielectric layers to expose the flanks of the thin silicon nitride layer. The silicon nitride layer is then etched back from all exposed sides to hasten the process on the same substrate processing mainframe. Both etching back the silicon oxide and etching back the silicon nitride use remotely excited fluorine-containing apparatuses attached to the same mainframe to facilitate performing both operations without an intervening atmospheric exposure. The process may also be reversed such that the silicon nitride is etched back first.

Feol low-k spacers

Abstract: Transistors and their methods of formation are described. Low dielectric constant material (e.g. a void) is placed between an elongated gate and a contact to increase the attainable switching speed of the gate of the device. An elongated structural slab of silicon nitride is temporarily positioned on both sides of the gate. Silicon oxide is formed over the silicon nitride slabs and the gate. Contacts are formed through the silicon oxide. The silicon oxide is selectively etched back to expose the silicon nitride slab. A portion or all the silicon nitride slab is removed and replaced with low-K dielectric or any dielectric with an air-gap to enable higher switching speed of the transistor. The highly-selective silicon nitride etch uses remotely excited fluorine and a very low electron temperature in the substrate processing region.

Method and apparatus for forming silicon nitride film

Abstract: Provided is a method of forming a silicon nitride film on a surface to be processed of a target object, which includes: repeating a first process a first predetermined number of times, the process including supplying a silicon source gas containing silicon toward the surface to be processed and supplying a decomposition accelerating gas containing a material for accelerating decomposition of the silicon source gas toward the surface to be processed; performing a second process of supplying a nitriding gas containing nitrogen toward the surface to be processed a second predetermine number of times; and performing one cycle a third predetermined number of times, the one cycle being a sequence including the repetition of the first process and the performance of the second process to form the silicon nitride film on the surface to be processed.

High selectivity gas phase silicon nitride removal

Abstract: A method of etching silicon nitride on patterned heterogeneous structures is described and includes a gas phase etch using partial remote plasma excitation. The remote plasma excites a fluorine-containing precursor and the plasma effluents created are flowed into a substrate processing region. A hydrogen-containing precursor, e.g. water, is concurrently flowed into the substrate processing region without plasma excitation. The plasma effluents are combined with the unexcited hydrogen-containing precursor in the substrate processing region where the combination reacts with the silicon nitride. The plasmas effluents react with the patterned heterogeneous structures to selectively remove silicon nitride while retaining silicon, such as polysilicon.

Deposition of boron and carbon containing materials

Abstract: Methods of depositing boron and carbon containing films are provided. In some embodiments, methods of depositing B,C films with desirable properties, such as conformality and etch rate, are provided. One or more boron and/or carbon containing precursors can be decomposed on a substrate at a temperature of less than about 400° C. In some embodiments methods of depositing silicon nitride films comprising B and C are provided. A silicon nitride film can be deposited by a deposition process including an ALD cycle that forms SiN and a CVD cycle that contributes B and C to the growing film.

Method of depositing ammonia free and chlorine free conformal silicon nitride film

Abstract: Provided herein are methods of depositing conformal silicon nitride films using atomic layer deposition by exposure to a halogen-free, N—H-bond-free, and carbon-free silicon-containing precursor such as disilane, purging of the precursor, exposure to a nitrogen plasma, and purging of the plasma at low temperatures. A high frequency plasma is used, such as a plasma having a frequency of at least 13.56 MHz or at least 27 MHz. Methods yield substantially pure conformal silicon nitride films suitable for deposition in semiconductor devices, such as in trenches or features, or for memory encapsulation.

Capped ald films for doping fin-shaped channel regions of 3-d ic transistors

Abstract: Disclosed herein are methods of doping a fin-shaped channel region of a partially fabricated 3-D transistor on a semiconductor substrate. The methods may include forming a multi-layer dopant-containing film on the substrate, forming a capping film comprising a silicon carbide material, a silicon nitride material, a silicon carbonitride material, or a combination thereof, the capping film located such that the multi-layer dopant-containing film is located in between the substrate and the capping film, and driving dopant from the dopant-containing film into the fin-shaped channel region. Multiple dopant-containing layers of the film may be formed by an atomic layer deposition process which includes adsorbing a dopant-containing film precursor such that it forms an adsorption-limited layer on the substrate and reacting adsorbed dopant-containing film precursor. Also disclosed herein are multi-station substrate processing apparatuses for doping the fin-shaped channel regions of partially fabricated 3-D transistors.

Aluminum oxide selective etch

Abstract: Methods of selectively etching aluminum oxide from the surface of a patterned substrate are described. The etch selectively removes aluminum oxide relative to other metal oxides and silicon-containing films such as silicon, polysilicon, silicon oxide, silicon germanium and/or silicon nitride. The methods include exposing aluminum oxide to plasma effluents formed in a remote plasma from a chlorine-containing precursor and a hydrocarbon. A remote plasma is used to excite the precursors and a local plasma is used to further excite the plasma effluents and accelerate ions toward the patterned substrate.

Air stable n-doping of WSe2 by silicon nitride thin films with tunable fixed charge density

Abstract: Stable n-doping of WSe2 using thin films of SiNx deposited on the surface via plasma-enhanced chemical vapor deposition is presented. Positive fixed charge centers inside SiNx act to dope WSe2 thin flakes n-type via field-induced effect. The electron concentration in WSe2 can be well controlled up to the degenerate limit by simply adjusting the stoichiometry of the SiNx through deposition process parameters. For the high doping limit, the Schottky barrier width at the metal/WSe2 junction is significantly thinned, allowing for efficient electron injection via tunneling. Using this doping scheme, we demonstrate air-stable WSe2 n-MOSFETs with a mobility of ∼70 cm2/V s.

Efficient silicon nitride grating coupler with distributed Bragg reflectors.

Abstract: In this paper we have designed, fabricated and characterized a high efficiency Silicon nitride grating coupler at 1490 nm. Distributed Bragg reflectors as bottom mirrors are employed to improve the coupling efficiency by reflecting the downward traveling light. The peak coupling efficiency obtained is about −2.5 dB and the 1-dB bandwidth is 53 nm. The fabrication process is CMOS-compatible and is ready to be integrated with photonic circuits.

Selective nitride etch

Abstract: Methods of selectively etching silicon nitride are provided. Silicon nitride layers are exposed to a fluorinating gas and nitric oxide (NO), which may be formed by reacting nitrous oxide (N 2 O) and oxygen (O 2 ) in a plasma. Methods also include defluorinating the substrate prior to turning off the plasma to increase etch selectivity of silicon nitride.

Nanoporous silicon nitride membranes fabricated from porous nanocrystalline silicon templates.

Abstract: The extraordinary permeability and manufacturability of ultrathin silicon-based membranes are enabling devices with improved performance and smaller sizes in such important areas as molecular filtration and sensing, cell culture, electroosmotic pumping, and hemodialysis. Because of the robust chemical and mechanical properties of silicon nitride (SiN), several laboratories have developed techniques for patterning nanopores in SiN using reactive ion etching (RIE) through a template structure. These methods however, have failed to produce pores small enough for ultrafiltration (<100 nm) in SiN and involve templates that are prone to microporous defects. Here we present a facile, wafer-scale method to produce nanoporous silicon nitride (NPN) membranes using porous nanocrystalline silicon (pnc-Si) as a self-assembling, defect free, RIE masking layer. By modifying the mask layer morphology and the RIE etch conditions, the pore sizes of NPN can be adjusted between 40 nm and 80 nm with porosities reaching 40%. The resulting NPN membranes exhibit higher burst pressures than pnc-Si membranes while having 5× greater permeability. NPN membranes also demonstrate the capacity for high resolution separations (<10 nm) seen previously with pnc-Si membranes. We further demonstrate that human endothelial cells can be grown on NPN membranes, verifying the biocompatibility of NPN and demonstrating the potential of this material for cell culture applications.

Methods for forming a self-aligned contact via selective lateral etch

Abstract: In some embodiments methods of processing a substrate include: providing a substrate having a contact structure formed on the substrate, wherein the contact structure comprises a feature defined by gate structures, a silicon nitride layer disposed on a upper surface of the gate structures and on sidewalls and a bottom of the feature, and an oxide layer disposed over the silicon nitride layer and filling the feature; etching an opening through the oxide layer to the silicon nitride layer disposed on the bottom of the opening, wherein a width of the opening is less than a width of the feature; expanding the opening in the oxide layer to form a tapered profile; exposing the substrate to ammonia and nitrogen trifluoride to form an ammonium fluoride gas that forms an ammonium hexafluorosilicate film on the oxide layer; and heating the substrate to a second temperature to sublimate the ammonium hexafluorosilicate film.

Effect of Reaction Mechanism on Precursor Exposure Time in Atomic Layer Deposition of Silicon Oxide and Silicon Nitride

Abstract: Atomic layer deposition (ALD) of highly conformal, silicon-based dielectric thin films has become necessary because of the continuing decrease in feature size in microelectronic devices. The ALD of oxides and nitrides is usually thought to be mechanistically similar, but plasma-enhanced ALD of silicon nitride is found to be problematic, while that of silicon oxide is straightforward. To find why, the ALD of silicon nitride and silicon oxide dielectric films was studied by applying ab initio methods to theoretical models for proposed surface reaction mechanisms. The thermodynamic energies for the elimination of functional groups from different silicon precursors reacting with simple model molecules were calculated using density functional theory (DFT), explaining the lower reactivity of precursors toward the deposition of silicon nitride relative to silicon oxide seen in experiments, but not explaining the trends between precursors. Using more realistic cluster models of amine and hydroxyl covered surfaces, the structures and energies were calculated of reaction pathways for chemisorption of different silicon precursors via functional group elimination, with more success. DFT calculations identified the initial physisorption step as crucial toward deposition and this step was thus used to predict the ALD reactivity of a range of amino-silane precursors, yielding good agreement with experiment. The retention of hydrogen within silicon nitride films but not in silicon oxide observed in FTIR spectra was accounted for by the theoretical calculations and helped verify the application of the model.

Wavelength dependence of Pockels effect in strained silicon waveguides.

Abstract: We investigate the influence of the wavelength, within the 1.3μm–1.63μm range, on the second-order optical nonlinearity in silicon waveguides strained by a silicon nitride (Si3N4) overlayer. The effective second-order optical susceptibility χxxy(2)¯ evolutions have been determined for 3 different waveguide widths 385 nm, 435 nm and 465 nm and it showed higher values for longer wavelengths and narrower waveguides. For wWG = 385 nm and λ = 1630 nm, we demonstrated χxxy(2)¯ as high as 336 ± 30 pm/V. An explanation based on the strain distribution within the waveguide and its overlap with optical mode is then given to justify the obtained results.

Influence of hBN content on mechanical and tribological properties of Si3N4/BN ceramic composites

Abstract: Silicon nitride materials containing 1–5wt% of hexagonal boron nitride (micro-sized or nano-sized) were prepared by hot-isostatic pressing at1700 ◦ C for 3h. Effect of hBN content on microstructure, mechanical and tribological properties has been investigated. As expected, the increaseof hBN content resulted in a sharp decrease of hardness, elastic modulus and bending strength of Si 3 N 4 /BN composites. In addition, the fracturetoughness of Si 3 N 4 /micro BN composites was enhanced comparing to monolithic Si 3 N 4 because of toughening mechanisms in the form of crackdeflection, crack branching and pullout of large BN platelets. The friction coefficient was not influenced by BN addition to Si 3 N 4 /BN ceramics.An improvement of wear resistance (one order of magnitude) was observed when the micro hBN powder was added to Si 3 N 4 matrix. Mechanicalwear (micro-failure) and humidity-driven tribochemical reaction were found as main wear mechanisms in all studied materials.© 2014 Elsevier Ltd. All rights reserved.

In Situ Controlled Growth of Titanium Nitride in Amorphous Silicon Nitride: A General Route Toward Bulk Nitride Nanocomposites with Very High Hardness

Abstract: Bulk nanocomposites possessing very high hardness in which TiN nanocrystallites are homogeneously embedded in an amorphous Si3N4 matrix are produced from perhydropolysilazane and tetrakisdimethylaminotitanium. That is, a low-molecular-weight TiN molecule is mixed in controlled molar ratio with a polymeric Si3N4 precursor; further processing, including ammonolysis, warm pressing, and controlled nanocrystal growth, yields nanocomposites with the desired properties.

Thermal stability and conductivity of hot-pressed Si3N4–graphene composites

Abstract: This study concerns new Si3N4–graphene composites manufactured using the hot-pressing method. Because of future applications of silicon nitride for cutting tools or specific parts of various devices having contact with high temperatures there is a need to find a ceramic composite material with good mechanical and especially thermal properties. Excellent thermal properties in the major directions are characteristic of graphene. In this study, the graphene phase is added to the silicon nitride phase in a quantity of up to 10 mass%, and the materials are sintered under uniaxial pressure. The mixture of AlN and Y2O3 is added as sintering activator to the composite matrix. The studies focus on thermal stability of produced composites in argon and air conditions up to the temperature of 1,000 °C. The research also concerns the influence of applied uniaxial pressure during the sintering process on the orientation of graphene nanoparticles in the Si3N4 matrix. The study also presents research on anisotropy of thermal diffusivity and following thermal conductivity of ceramic matrix composites versus the increasing graphene quantity. Most of the presented results have not been published in the literature yet.

Memory transistor with multiple charge storing layers and a high work function gate electrode

Abstract: A semiconductor device includes an oxide-nitride-oxide (ONO) dielectric stack on a surface of a substrate, and a high work function gate electrode formed over a surface of the ONO dielectric stack. The ONO dielectric stack includes a multi-layer charge storage layer including a silicon-rich, oxygen-lean top silicon nitride layer and an oxygen-rich bottom silicon nitride layer. The high work function gate electrode includes a P+ doped polysilicon layer.