Method for producing liquid discharge head

A method for producing a liquid discharge head including a silicon substrate having, on a first surface, energy generating elements configured to generate energy for discharging liquid from discharge ports, and a supply port penetrating the substrate from the first surface to a second surface, which is a rear surface of the first surface of the substrate, the supply port being configured to supply liquid to the energy generating elements, the method comprising the steps of:

• preparing the silicon substrate having a sacrifice layer that is in contact with a portion of the first surface where the ink supply port is to be formed and is composed of a material capable of being isotropically etched by an alkaline solution, and an etching mask layer having a plurality of openings on the second surface, the etching rate by the alkaline solution of a portion of the sacrifice layer at a position corresponding to a portion between two adjacent said openings being lower than the etching rate by the alkaline solution of a portion of the sacrifice layer at a position corresponding to the opening;
• exposing the sacrifice layer by performing crystal anisotropic etching on the silicon substrate from the plurality of openings with the alkaline solution;
• and
• etching the sacrifice layer with the alkaline solution.