Patent ID: 8865009

Claim:
A process for producing a substrate with a piercing aperture, the piercing aperture being formed by conducting dry etching from the side of a second surface to a first surface of a substrate, the second surface being opposite to the first surface, the process comprising, in the following order, the steps of: (a) forming a groove around a region where the piercing aperture is to be formed in the first surface of the substrate; (b) forming a first etch-stop layer in the region where the piercing aperture is to be formed in the first surface of the substrate and a second etch-stop layer in the interior of the groove; and (c) conducting the dry etching from the side of the second surface until reaching the first etch-stop layer to form the piercing aperture, wherein the second etch-stop layer is formed at a position closer to the second surface than a part of the first etch-stop layer, to which the dry etching reaches, is to the second surface.