Degussa Aktiengesellschaft

Evonik Degussa Gmbh

Nippon Aerosil Co., Ltd.

Paul Brandl

Kai Schumacher

Naruyasu Ishibashi

Christian Schulze-Isfort

Toshio Morii

Mitsuru Ochiai

Hitoshi Kobayashi

Silica glass granule having the following features:  It is prepared by

Method of making silica-glass granule from pyrogenic silica powder

Pyrogenically produced silicon dioxide powder in the form of aggregates of primary particles having a BET surface area of 300&#xb1;25 m/g, wherein the aggregates display an average surface area of 4800 to 6000 nm, an average equivalent circle diameter (ECD) of 60 to 80 nm and an average circumference of 580 to 750 nm. It is produced by a pyrogenic process in which silicon tetrachloride and a maximum of up to 40 wt. % of a second silicon component comprising HSiCl, HSiCl, HSiCl, CHSiCl, (CH)SiCl, (CH)SiCl and/or (n-CH)SiClare mixed with primary air and a combustion gas and burnt into a reaction chamber, secondary air also being introduced into the reaction chamber, and the feed materials being chosen such that an adiabatic flame temperature of 1390 to 1450&#xb0; C. is obtained. It can be used as a filler.

Pyrogenically produced silicon dioxide powder

A high concentration silica slurry can be used for polishing of substrates, such as semiconductor materials. The slurry contains a silica powder dispersed in an solvent. The silica slurry has a silica concentration of more than 50% by weight and a viscosity of less than 1000 mPa&#xb7;s, wherein the silica powder has a ratio DL/DT of less than 1.3, wherein DL is an average particle size of the silica powder measured by a laser diffraction particle size distribution method and DT is an average primary particle size of the silica powder measured by a TEM photography observation, and wherein the silica powder has an average primary particle size of from 0.08 &#x3bc;m to 0.8 &#x3bc;m.

High concentration silica slurry

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Yokkaichi, Japan

Paul Brandl