Method of manufacturing substrate for liquid discharge head

A method of manufacturing a substrate for a liquid discharge head having a supply port which passes through a silicon substrate provided with an energy-generating element which generates the energy used to discharge a liquid and which allows the liquid to be supplied to the energy-generating element therethrough, the method comprising the steps of:

• preparing a silicon substrate in which a first etching mask having a first opening is provided on a first face of the silicon substrate, and a second etching mask having a second opening is provided on a second face of the silicon substrate that is a rear face of the first face;
• forming a first recess in the silicon substrate towards the second face from the first face within the first opening, and forming a second recess in the silicon substrate towards the first face from the second face within the second opening, a bottom of the first recess being closer to the second face than a bottom of the second recess;
• and
• after forming the first recess and the second recess, performing crystalline anisotropic etching to the silicon substrate using the first and second etching masks as masks from both the faces of the first and second faces, thereby forming the supply port.