Making method of optical waveguide substrate

Abstract

A method of making a high quality optical waveguide substrate is provided, in which the surface of a silicon substrate is oxidized through relatively large thickness and no foreign matter particles are adhered on the surface thereof. The silicon substrate to form a quartz film for the optical waveguide is mounted on a carbon contained ceramics sample base and is inserted into a carbon contained ceramics furnace core tube of which its external circumference is arranged in a heating furnace. When the inside of the furnace core tube is heated to 200 to 600° C. by the heating furnace, an oxidant gas for the silicon substrate surface is introduced, then by further heating up to 1200 to 1350° C., the silicon surface is thus oxidized.

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