Patent ID: 8808555

Claim:
A method of manufacturing a substrate for a liquid discharge head including a first face, energy generating elements which generate the energy to be used to discharge a liquid to a second face opposite to the first face, and liquid supply ports for supplying the liquid to the energy generating elements, the method comprising the steps of: preparing a silicon substrate having, at the first face, an etching mask layer having an opening corresponding to a portion where the liquid supply ports are to be formed and having first recesses provided within the opening of the etching mask layer, and second recesses provided in the region of the second face where the liquid supply ports are to be formed, the first recesses and the second recesses being separated from each other by a portion of the substrate; and etching the silicon substrate by crystal anisotropic etching from the opening of the first face to form the liquid supply ports, wherein T is defined as the thickness of the silicon substrate, X is defined as the depth of the first recesses, Y is defined as the depth of the second recesses, and the following relationship is satisfied: X+Y>T.