Piezoelectric element and method for manuacturing piezoelectric element

Abstract

A piezoelectric element with a substrate, a first electrode film disposed on the substrate, a piezoelectric film disposed on the first electrode film, and a second electrode film disposed on the piezoelectric film, and a method of forming same. The piezoelectric film has a laminated structure composed of a plurality of crystallized piezoelectric thin films. The piezoelectric film has a predetermined thickness and is formed by repeated cycles of a film formation step of forming a piezoelectric thin film and a crystallization heat treatment step of heat-treating the piezoelectric thin film to effect crystallization.

1 . A method for manufacturing a piezoelectric element, the method comprising the steps of:
 forming a first electrode film on a substrate;   forming a piezoelectric film on the first electrode film; and   forming a second electrode film on the piezoelectric film,   wherein the piezoelectric film has a predetermined thickness and is formed by repeated cycles of film formation of forming a piezoelectric thin film and crystallization heat treatment of heat-treating the piezoelectric thin film to effect crystallization.   
   
   
       2 . The method for manufacturing a piezoelectric element according to  claim 1 ,
 wherein the thickness of piezoelectric thin film formed per cycle is 350 nm or less.   
   
   
       3 . The method for manufacturing a piezoelectric element according to  claim 1 ,
 wherein the crystallization heat treatment is conducted within the range of 700° C. or more and 800° C. or less.   
   
   
       4 . The method for manufacturing a piezoelectric element according to  claim 1 ,
 wherein the film formation of the piezoelectric thin film is conducted by a sputtering method in an oxygen gas atmosphere.   
   
   
       5 . The method for manufacturing a piezoelectric element according to  claim 4 ,
 wherein the oxygen gas atmosphere is an atmosphere of mixed gas of an oxygen gas and an inert gas, and   the partial pressure of oxygen gas is 50% or more.   
   
   
       6 . The method for manufacturing a piezoelectric element according to  claim 1 ,
 wherein the piezoelectric thin film comprises lead zirconate titanate, and   the lead content of a target for sputtering is 1.02 or more and 1.1 or less relative to the total content of titanium and zirconium of 1 on an atomic weight basis.   
   
   
       7 . The method for manufacturing a piezoelectric element according to  claim 1 ,
 wherein the step of forming the first electrode film includes the steps of:   forming a titanium layer on the substrate; and   forming a platinum layer on the titanium layer.   
   
   
       8 . The method for manufacturing a piezoelectric element according to  claim 7 ,
 wherein the film thickness of the titanium layer is within the range of 5 nm or more and 20 nm or less.   
   
   
       9 . The method for manufacturing a piezoelectric element according to  claim 1 , the method further comprising the steps of:
 patterning the second electrode film after forming the second electrode film;   patterning the piezoelectric film after the second electrode film is patterned; and   patterning the first electrode film after the piezoelectric film is patterned.   
   
   
       10 . The method for manufacturing a piezoelectric element according to  claim 9 ,
 wherein the patterning of the piezoelectric film is conducted by a wet etching method.   
   
   
       11 . The method for manufacturing a piezoelectric element according to  claim 1 ,
 wherein the formation and the patterning of a plurality of the first electrode films, a plurality of the piezoelectric films, and a plurality of the second electrode films are conducted simultaneously on the substrate, and   individual polarization treatments of the plurality of piezoelectric films are conducted simultaneously through wirings disposed on the substrate.   
   
   
       12 . The method for manufacturing a piezoelectric element according to  claim 11 ,
 wherein the wirings are removed by dissolution after the polarization treatments are conducted.   
   
   
       13 . The method for manufacturing a piezoelectric element according to  claim 11 ,
 wherein the wirings are removed by grinding after the polarization treatments are conducted.   
   
   
       14 . The method for manufacturing a piezoelectric element according to  claim 11 ,
 wherein the ratio of the polarization treatment temperature of the piezoelectric film to the Curie temperature of the piezoelectric film is 0.2 or more.   
   
   
       15 . The method for manufacturing a piezoelectric element according to  claim 11 ,
 wherein the first electrode film is connected to a negative electrode and the second electrode film is connected to a positive electrode in the polarization treatment of the piezoelectric film.