Patent ID: 8613862

Claim:
A manufacturing method, for a liquid discharge head substrate that includes a silicon substrate in which a liquid supply port is formed, comprising the steps of: preparing the silicon substrate, on one face of which a mask layer, in which an opening has been formed, is deposited; forming a first recessed portion in the silicon substrate, so that the first recessed portion is extended through the opening from the one face of the silicon substrate toward the other face, which is an opposite face of the one face, the first recessed portion ending in a terminus near the opposite face; forming a second recessed portion by performing wet etching of the substrate, via the first recessed portion, using the mask layer; and performing dry etching of the silicon substrate in a direction from the second recessed portion to the other face, wherein D 2 >D−D 1 is satisfied, where D 2 is a depth obtained by the dry etching, D 1 is a depth of the first recessed portion from the one face to the terminus and D is a thickness of the substrate, the depth D 2 obtained by the dry etching being defined as a dimension from i) a position where the substrate is etched closest to the one face in the dry etching to ii) the other face, and the position where the substrate is etched closest to the one face in the dry etching step is closer to the one face than the terminus of the first recessed portion is to the one face.