Method for manufacturing silicon substrate with silicon oxide film

Abstract

[Problem] To provide a manufacturing method that can produce a silicon substrate with a silicon oxide film of 2 μm or more, which is less prone to warping or deformation, has excellent film quality (hardness, refractive index, light transmittance), and is not easily warped or deformed in a very short time. [Solution] The method includes: a first step of patterning an etch mask for deep trenches on the surface of a silicon substrate; a second step of forming deep trenches on the silicon substrate using depth reactive ion etching (D-RIE); and a third step of forming a thick silicon oxide film by oxidizing the surface of the silicon substrate with deep trenches using a thermal oxidation method, oxidizing all the silicon in the ridges defined by the deep trenches, and filling the deep trenches with volume-expanded silicon oxide.

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