Patent ID: 9263650
Filing Date: 2016-02-16
CPC Classification: H01L

Claim Text:
1. A method for making an epitaxial substrate, comprising: (a) forming a light-transmissive layer on a flat upper surface of a base member, the light-transmissive layer being made of a light-transmissive material having a refractive index lower than that of the base member; (b) forming a mask layer on the light-transmissive layer, the mask layer being made of a photoresist material; (c) patterning the mask layer to obtain a patterned mask constituted by a plurality of mask segments which are displaced from one another in a longitudinal direction by a plurality of gaps that expose a plurality of first regions of the light-transmissive layer from the patterned mask, and which are superimposed upon a plurality of second regions of the light-transmissive layer, respectively, each of the mask segments having at least a corner edge; (d) heat-treating the patterned mask at a temperature close to a glass transition temperature of the photoresist material such that the corner edge of each of the mask segments is rounded so as to permit each of the mask segments to acquire a cone-shaped profile; and (e) subjecting the exposed first regions and the heat-treated patterned mask to a dry-etching treatment, such that the first regions and the heat-treated patterned mask are removed, therein permitting each of the second regions left on the base member to have a profile similar to the cone-shaped profile.