Patent ID: 8252365

Claim:
A method of manufacturing a liquid ejection head including an ejection port from which liquid is ejected, an ejection side flow channel which is connected to the ejection port, a pressure chamber which is connected to the ejection side flow channel and accommodates the liquid to be ejected from the ejection port, and a piezoelectric element which pressurizes the liquid accommodated in the pressure chamber, the method comprising: a lower electrode forming step of forming a lower electrode on a surface of a substrate; a piezoelectric film deposition step of depositing a piezoelectric film made of a piezoelectric material by one of epitaxial growth and oriented growth onto a surface of the lower electrode reverse to a surface of the lower electrode that is adjacent to the substrate; an upper electrode forming step of forming an upper electrode onto a surface of the piezoelectric film reverse to a surface of the piezoelectric film that is adjacent to the lower electrode; a pressure chamber forming step of forming the pressure chamber on a surface of the substrate reverse to the surface on which the lower electrode is formed; a flow channel plate bonding step of bonding a flow channel plate formed with the ejection side flow channel to the substrate in which the pressure chamber is formed, after registering the ejection side flow channel and the pressure chamber mutually in position; an ejection port plate bonding step of bonding an ejection port plate formed with the ejection port to the flow channel plate, after registering the ejection port and the ejection side flow channel mutually in position; a wiring member bonding step of bonding a wiring member to the upper electrode under an environment of first temperature ranging from 130° C. to 150° C., the wiring member having a wiring pattern to be connected to an external device; and a polarization direction reversal step of, immediately after the wiring member bonding step, under an environment of second temperature ranging from 10° C. to 70°, reversing a polarization direction of the piezoelectric film by applying an alternating electric field of an intensity not lower than a coercive electric field of the piezoelectric material, between the upper electrode and the lower electrode, and then applying a direct electric field of an intensity not lower than the coercive electric field in a direction from the upper electrode toward the lower electrode.