Method for manufacturing liquid ejection head

A method for manufacturing a liquid ejection head including a substrate provided with an energy generating element, a flow path forming member that forms a flow path, an ejection port forming member including an ejection port surface provided with an ejection port that ejects, with energy from the energy generating element, a liquid supplied from the flow path, the method of manufacturing the liquid ejection head comprising:

• providing a negative first photosensitive resin layer on the substrate;
• forming a pattern of the flow path by selectively exposing the first photosensitive resin layer;
• providing a negative second photosensitive resin layer on the first photosensitive resin layer;
• providing a negative third photosensitive resin layer on the second photosensitive resin layer;
• forming a pattern of the ejection port by selectively exposing the second and third photosensitive resin layers;
• developing the first, second, and third photosensitive resin layers;
• irradiating an activation energy line on at least one of the second and third photosensitive resin layers after the developing;
• and
• heat curing the first, second, and third photosensitive resin layers after the irradiating of the activation energy line.