Method for manufacturing liquid ejection head

A method for manufacturing liquid ejection heads, comprising the steps of:

• forming ejection port members on a substrate, the ejection port members each having a liquid channel and an ejection port for ejecting liquid through the liquid channel, the liquid channel communicating with the substrate;
• forming supply ports passing through the substrate to supply liquid to the channels;
• forming separation grooves in the substrate to separate the substrate for each liquid ejection head, the separation grooves not penetrating the substrate;
• in a state that the separation grooves are not penetrating the substrate, cutting the substrate for each liquid ejection head along the separation grooves;
• and
• forming a supporting member on the substrate,
• wherein the step of forming the ejection port members includes the step of hardening a material constituting the ejection port members by heat treatment,
• wherein the step of forming the separation groove is performed before the step of hardening,
• wherein the step of cutting the substrate is performed after the step of forming the ejection port members,
• wherein, the supply ports are formed to pass through the substrate, and the supply ports and the separation grooves are formed not to pass through the supporting member;
• and
• wherein the substrate is formed of silicon.