Disclosed is a semiconductor light emitting chip (20) that is composed of: a substrate (10), which has the C plane of a sapphire single crystal as the front surface, and the side surfaces (25, 26) configured of planes that intersect all the planes equivalent to the M plane of the sapphire single crystal, and which includes modified regions (23, 24) in the side surfaces (25, 26), the modified regions being formed by laser radiation; and a light emitting element (12), which is provided on the substrate front surface (10a) of the substrate (10). In the semiconductor light emitting chip, a tilt of the substrate side surfaces with respect to the substrate front surface is suppressed. Also disclosed is a method for processing the substrate.