Method for manufacturing nozzle plate for liquid ejection head, nozzle plate for liquid ejection head and liquid ejection head

A method for manufacturing a nozzle plate for a liquid ejection head, wherein a through hole whose one opening is an ejection port ejecting liquid is arranged on a Si substrate by an anisotropic etching process in which etching and side wall protection film formation are alternately repeated in the Si substrate, the method comprising the following steps performed in the following order:

• forming a film to be an etching mask on a surface of the Si substrate whereupon the ejection port is to be formed;
• forming the etching mask pattern having an opening for forming the through hole by performing photolithography and etching to a film to be the etching mask;
• and
• performing etching by the anisotropic etching process by satisfying a conditional relationship below:
• D≦0.1×R
• where D is a depth of an etching per one cycle, wherein, in the anisotropic etching process, a repeating unit in which etching and side wall protection film formation are alternately repeated is set to be one cycle, and R is a diameter of an opening of the etching mask pattern to form the through hole.