Piezoelectric actuator, method of manufacturing same, and liquid ejection head

Abstract

The piezoelectric actuator comprises: a supporting substrate; a thermal stress controlling layer which is formed on the supporting substrate; and a piezoelectric body which is formed as a film onto the thermal stress controlling layer on the supporting substrate at a higher temperature than room temperature, wherein the thermal stress controlling layer reduces a film stress induced by formation of the piezoelectric body.

1 . A method of making a piezoelectric actuator that has a supporting substrate, a thermal stress controlling layer, and a piezoelectric body, the method comprising:
 selecting a thermal expansion coefficient for the thermal stress controlling layer, wherein the thermal expansion coefficient of the thermal stress controlling layer is selected according to a first thermal expansion coefficient and a second thermal expansion coefficient, the first thermal expansion coefficient being a thermal expansion coefficient of the piezoelectric body, the second thermal expansion coefficient being a thermal expansion coefficient of the supporting substrate;   forming the thermal stress controlling layer on the supporting substrate;   forming, as a film, the piezoelectric body onto the thermal stress controlling layer at a temperature higher than room temperature, wherein said forming as a film is performed after said forming the thermal stress controlling layer; and   reducing, with said thermal stress controlling layer, a film stress induced by formation of the piezoelectric body.   
   
   
       2 . The method of  claim 1 , wherein forming as a film includes forming the piezoelectric body by an aerosol deposition method. 
   
   
       3 . The method of  claim 2 , wherein the piezoelectric body formed by the aerosol deposition method is a PZT piezoelectric film. 
   
   
       4 . The method of  claim 1 , wherein selecting further comprises selecting a first thermal expansion coefficient, a second thermal expansion coefficient, and a thermal expansion coefficient for the thermal stress controlling layer such that the second thermal expansion coefficient is lower than the first thermal expansion coefficient, and the thermal expansion coefficient of the thermal stress controlling layer is higher than the first thermal expansion coefficient. 
   
   
       5 . The method of  claim 1 , wherein forming the thermal stress controlling layer includes forming the thermal stress controlling layer by at least one of a sputtering method, a plating method, or an aerosol deposition method.