Method for producing liquid-jet head

A method for producing a liquid-jet head, comprising the steps of:

• forming piezoelectric elements, each of which consists of a lower electrode, a piezoelectric layer, and an upper electrode, on one surface of a passage-forming substrate via a vibration plate, the passage-forming substrate being to have, formed therein, pressure generating chambers communicating with nozzle orifices for ejection of a liquid, and a communicating portion communicating with the pressure generating chambers, and removing the vibration plate in a region for serving as the communicating portion to form an exposed portion where the surface of the passage-forming substrate is exposed;
• forming a wiring layer on the surface of the passage-forming substrate on a side of the piezoelectric elements, also forming the wiring layer on the passage-forming substrate within the exposed portion, and patterning the wiring layer in a region corresponding to the piezoelectric elements to form lead electrodes leading from the piezoelectric elements;
• bonding a reservoir forming plate to the one surface of the passage-forming substrate, the reservoir forming plate having, formed therein, a reservoir portion communicating with the communicating portion and constituting a part of a reservoir;
• wet-etching the passage-forming substrate at another surface thereof until the vibration plate and the wiring layer within the exposed portion are exposed to form the pressure generating chambers and the communicating portion;
• forming a protective film comprising a material having liquid resistance on inner surfaces of the pressure generating chambers and the communicating portion;
• removing the protective film provided on the wiring layer within the exposed portion;
• and
• performing wet etching on a side of the communicating portion to remove the wiring layer, thereby establishing communication between the reservoir portion and the communicating portion.