Tokuyama (TKYMF) USPTO patentsUtility application

To provide a fluidized-bed reaction vessel and a trichlorosilane production method each of which can reduce corrosion and wear of a reaction container inner wall, a fluidized-bed reaction vessel causes metallurgical grade silicon powder and hydrogen chloride gas to react with each other for production of trichlorosilane.

A method for effectively removing minute impurities of 1 μm or less in size that are present on a surface of an aluminum nitride single-crystal substrate without etching the surface includes scrubbing a surface of an aluminum nitride single-crystal substrate using a polymer compound material having lower hardness than an aluminum nitride single crystal, and an alkali aqueous solution having 0.01-1 mass % concentration of potassium hydroxide or sodium hydroxide, the alkali aqueous solution being absorbed in the polymer compound material.