Patent ID: 8623674

Claim:
A method of manufacturing a liquid ejection head substrate including a silicon substrate having a first surface, a second surface disposed opposite to the first surface, and a liquid supply port and slots for supplying liquid to a liquid channel arranged on the first surface, the liquid supply port being formed as hollow at the side of the second surface, the slots being formed as through holes communicating with both the bottom of the hollow and the first surface, the method comprising: (1) a step of executing a first etching process from the side of the second surface to form the hollow in the silicon substrate; (2) a step of forming a first resist on the second surface and on the hollow; (3) a step of executing a second etching process on the first resist to remove at least the first resist on the bottom of the hollow, the second etching process being executed under conditions of securing an equal etching rate to both the silicon substrate and the first resist; (4) a step of forming a second resist on the hollow; (5) a step of forming an etching mask by patterning the second resist; and (6) a step of executing a third etching process, using the etching mask, to form the through holes, the above steps being conducted in the above listed order.