Onoda Cement Co., Ltd.

Speedfam Co Ltd

Nissan Chemical Industries Limited

Speedfam-ipec Co Ltd

Speedfam-pec Co Ltd

Hiroaki Tanaka

Akitoshi Yoshida

Yoshihisa Ogawa

Takeshi Furukawa

Satoru Fujii

Yutaka Kimura

Shunji Hakomori

Masamichi Obitsu

Mitsuhiro Ito

Takamiki Tamashige

Ryosuke Narishima

Masaaki Muraoka

Yusuke Inoue

A polishing compound in the form of a dispersion containing silicon oxide particles having an average diameter of 8 to 500 manometers and at least one kind of metal compound particles having an average diameter of 10 to 3000 nanometers and selected from metal oxides, metal nitrides and metal carbides. The concentration of silicon oxide particles is 1 to 15 wt. %. The concentration of silicon oxide particles is 0.1 to 10 wt. %. The pH of the dispersion is 8.3 to 11.5, and is buffered by the addition of a buffering combination composed of weak acid and/or weak base, wherein the logarithms of reciprocal number of acid dissociation constant at 25&deg; C. of the weak acid and/or weak base is 8.0 to 12.5.

Polishing compound and an edge polishing method thereby

The present invention is a polishing compound comprising a colloidal solution containing 1&tilde;15 wt. % of silicon oxide particles of 8&tilde;500 nanometer average diameter, wherein said colloidal solution is prepared as a buffer solution which has buffering action between pH 8.7&tilde;10.6 by the addition of one combination selected from groups composed by weak acid and strong base, strong acid and weak base or weak acid and weak base, and logarithms of reciprocal number of acid dissociation constant at 25&deg; C. of said weak acid and/or weak base is 8.0&tilde;12.0.

Polishing compound and a method for polishing

The present invention provides a polishing compound which does not make stain grow on the surface of work-piece comprising, the dispersion containing 1-30 wt. % of metal oxide particles having 8-500 nm average diameter, acid or alkali and salt, and whose pH is 7-12. Desirably said polishing compound is the compound in which water soluble organic solvent is contained. Further, present invention provides edge polishing method and surface polishing method by use of said polishing compound.

Polishing method for silicon wafers which uses a polishing compound which reduces stains

The present invention is a polishing compound comprising a colloidal solution of silicon oxide to which an alkaline component and an acid component are added in order to have a buffering action, wherein said alkali component is a quaternary ammonium whose carbon number per one molecular is smaller than 12, and said acid component is at least one selected from the group composed by carbonic acid, boric acid and silicic acid.

Polishing compound and a polishing method for silicon wafer

A zirconia ceramic composed of crystals which scarcely undergo phase transformation from tetragonal system to monoclinic in the temperature range of from 100.degree. C. to 300.degree. C. even in the presence of water vapor or water is disclosed, said zirconia ceramic comprising at least 93% by weight of partially stabilized zirconia mainly composed of tetragonal crystals and containing mainly Y.sub.2 O.sub.3 and ZrO.sub.2 at the former to the latter molar ratio of from 2/98 to 4.5/95.5 and balance of at least one of the oxides selected from the group consisting of boron oxide, germanium oxide, and gallium oxide, wherein the content of the boron oxide is 1% by weight or less.

Zirconia ceramics

In a classifier having a rotary classifying impeller in a casing for discharging fine powder to the outside of the casing, a leakage prevention apparatus is provided for the classifier which has a rotary seal member mounted on the upper plate of the rotary classifying impeller at the boundary portion between the rotary classifying impeller and a fine powder discharge duct. The upper portion of the rotary seal member protrudes outwardly from an opening in the top plate of the casing to separate the reduced air pressure in the discharge duct perfectly from the high pressure in the raw material dispersion chamber which is radially outside of the seal member. Furthermore, the rotary seal member can be provided with a circular groove in a J-shaped sectional structure. The end portion of this rotary seal member can also be formed into a square shape, a rounded shape or an inclined acute shape.

Leakage prevention apparatus for a classifier

In a classifier including a rotary disc provided on a lower end of a vertical rotary shaft depending from the top of a hopper-type casing, a horizontal dispersing disc is provided directly below the top of the casing, a circular collision plate is spaced from the outer circumference of the horizontal dispersing disc, and a plurality of vortex adjusting members are secured at their upper ends to the horizontal dispersing disc and at their lower ends to the rotary disc, and a leakage prevention apparatus is provided which comprises a plurality of dispersing and classifying vanes spaced from the outside of the vortex adjusting members and the inner sides of the collision plate. The dispersing and classifying vanes depend from the under surface of the horizontal dispersing disc for an appropriate length. Furthermore, the leakage prevention apparatus can also comprise a ring for preventing the introduction of coarse powder which is provided on the outer circumference of the horizontal dispersing disc, the ring depending from the under surface of such horizontal dispersing disc for an appropriate length.

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Narashino, Japan

Hiroaki Tanaka