Ceradyne, Inc.

Lam Research Corporation

Biljana Mikijelj

Shanghua Wu

Mukund Srinivasan

Travis R Taylor

Karl A Schwetz

Georg P Victor

Bobby Kadkhodayan

K Y Ramanujam

A silicon nitride material is disclosed which has properties beneficial for efficient operation of a corona discharge igniter system in an internal combustion gas engine.

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A silicon nitride material is disclosed which has properties necessary for efficient operation of a corona discharge igniter system in an internal combustion gas engine allowing an increase in fuel efficiency of over 10%. The material is disclosed in a range of compositions, all of which exhibit high dielectric strengths, high mechanical strength, thermal shock resistance and fracture toughness, low dielectric constant and loss tangent and electrical resistivity, all of which significantly increase the efficiency of the igniter system over current state of the art alumina insulators. Moreover, the materials retain their dielectric strength and structural integrity at elevated temperatures, up to 800&#xb0; C.-1000&#xb0; C. One embodiment comprises a sintered silicon nitride process comprising powder batching, binder removal and sintering. In the preferred embodiment the method of manufacture for silicon nitride is an SRBSN process comprising powder batching, powder pressing, binder removal, nitriding and sintering.

Silicon nitride materials with high strength, fracture toughness values, and Weibull moduli simultaneously, due to unique large grain reinforcing microstructures and well engineered grain boundary compositions. The invention demonstrates that, surprisingly and contrary to prior art, a silicon nitride material can be made which simultaneously has high strength above about 850-900 MPa, a Weibull above about 15 and high fracture toughness (above about 8 and 9 MPa&#xb7;m), and has reinforcing grains longer than 5 &#x3bc;m, typically longer than 10 &#x3bc;m in the microstructure without compromising its properties and reliability. The product of this invention can be processed using a variety of densification methods, including gas-pressure sintering, hot pressing, hot isostatic pressing, but is not limited to these, and does not require multiple heat treatments for all of these features to be achieved.

Dense silicon nitride body having high strength, high Weibull modulus and high fracture toughness

A method of increasing mean time between cleans of a plasma etch chamber and chamber parts lifetimes is provided. Semiconductor substrates are plasma etched in the chamber while using at least one sintered silicon nitride component exposed to ion bombardment and/or ionized halogen gas. The sintered silicon nitride component includes high purity silicon nitride and a sintering aid consisting of silicon dioxide. A plasma processing chamber is provided including the sintered silicon nitride component. A method of reducing metallic contamination on the surface of a silicon substrate during plasma processing is provided with a plasma processing apparatus including one or more sintered silicon nitride components. A method of manufacturing a component exposed to ion bombardment and/or plasma erosion in a plasma etch chamber, comprising shaping a powder composition consisting of high purity silicon nitride and silicon dioxide and densifying the shaped component.

High lifetime consumable silicon nitride-silicon dioxide plasma processing components

A dense silicon carbide (SiC) material with boron (B), nitrogen (N) and oxygen (O) as the only additives and with excellent insulting performance (electrical volume resistivity greater than 1&#xd7;10&#x3a9;&#xb7;cm). The SiC ceramic material, made from a powder mix of, by weight, from 0.1 to 7% boron carbide, from 0.1 to 7% silicon nitride, from 0.1 to 6% silicon dioxide, and a balance of &#x3b1;-SiC, consists essentially of (1) at least 90% by weight of &#x3b1;-SiC, (2) about 0.3 to 4.0% by weight of boron, (3) about 0.1 to 6.0% by weight of nitrogen, (4) about 0.06 to 0.5% by weight of oxygen, and (5) no more than 0.07% by weight of metallic impurities; wherein the boron and nitrogen are present according to an B/N atomic ratio of 0.9 to 1.5. In particular, this material is suitable for applications in plasma etching chambers for semiconductor and integrated circuit manufacturing.

High resistivity SiC material with B, N and O as the only additions

High-volume, fully dense, multi-component monoliths with microstructurally indistinguishable joints that can be used as refractory, corrosion and wear resistant components in the non-ferrous metal industry. The SiNmonoliths according to the invention comprise at least 90% by weight &#x3b2;-type SiNand up to 10% by weight of a predominantly amorphous binder phase, said binder phase being formed from compositions of the rare earth metal &#x2014;Al&#x2014;Si&#x2014;O&#x2014;N, rare earth metal &#x2014;Mg&#x2014;Si&#x2014;O&#x2014;N or Mg&#x2014;Si&#x2014;O&#x2014;N systems. Preferably the rare earth metal is yttrium (Y). The monoliths have a volume of greater than 250 cm. A method of making the multi-component monoliths is achieved by simultaneously joining and uniaxially hot pressing an assembly of reaction bonded silicon nitride bodies (RBSN bodies). RBSN bodies are placed in contact with each other in the substantial absence of any interlayer or ceramic paste in between.

High-volume, fully dense silicon nitride monolith and method of making by simultaneously joining and hot pressing a plurality of RBSN parts

This disclosure describes sintered bodies comprising about 90 wt % to about 99 wt % of boron carbide, having a B:C atomic ratio ranging from 3.8 to 4.5:1; 0 to 1 wt % free carbon; 0 to 1 wt % BN or AlN, remainder an oxide binder phase; said sintered body having a uniform microstructure composed of substantially equiaxed grains of said boron carbide; the oxide binder phase comprising at least a rare earth aluminate and optionally AlOor other ternary or binary phases of rare earth oxide-alumina systems; the binder phase being present in form of pockets at the multiple grain junctions and the density of no more than 2.6 g/cm. Also described is a manufacturing process for the above described substantially pore-free, sintered boron carbide materials with high strength and fracture toughness, which can be used for production of large-area parts. This is achieved by liquid phase low temperature-low pressure hot pressing of boron carbide in an argon atmosphere.

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Cerritos, CA, United States of America

Biljana Mikijelj