Piezoelectric device

Abstract

A piezoelectric device that includes: a diaphragm; a supporting part configured to support at least a portion of an end of the diaphragm; a piezoelectric film disposed along a portion supported by the supporting part on the diaphragm, a width of the film along the supported portion being narrower than a width of the portion; a lower electrode disposed at a face of the piezoelectric film on a diaphragm side; and an upper electrode disposed on a face of the piezoelectric film on an opposite side to the diaphragm.

I (we) claim: 
     
         1 . A piezoelectric device comprising:
 a diaphragm having a first surface and a second surface;   a supporting part adjacent the second surface of the diaphragm and configured to support at least a portion of an end of the diaphragm;   a piezoelectric film adjacent the first surface of the diaphragm and disposed along the portion of the end of the diaphragm supported by the supporting part, a width of the piezoelectric film along the supported portion being narrower than a width of the supported portion; and   an electrode disposed on a surface of the piezoelectric film opposite to the diaphragm.   
     
     
         2 . The piezoelectric device according to  claim 1 , wherein the diaphragm is formed of a degenerate semiconductor. 
     
     
         3 . The piezoelectric device according to  claim 2 , wherein the electrode is an upper electrode and the diaphragm is configured to function as a lower electrode for the piezoelectric film. 
     
     
         4 . The piezoelectric device according to  claim 1 , wherein the electrode is an upper electrode and the piezoelectric device includes a lower electrode disposed on a surface of the diaphragm. 
     
     
         5 . The piezoelectric device according to  claim 1 , wherein the diaphragm has a substantially rectangular shape. 
     
     
         6 . The piezoelectric device according to  claim 5 , wherein the supporting part is configured to support a pair of opposing sides of the diaphragm. 
     
     
         7 . The piezoelectric device according to  claim 6 , further comprising a plurality of piezoelectric films disposed along each side of the pair of sides of the diaphragm. 
     
     
         8 . The piezoelectric device according to  claim 7 , wherein the diaphragm is divided along a first substantial center line substantially parallel to the pair of opposing sides. 
     
     
         9 . The piezoelectric device according to  claim 8 , wherein the diaphragm is further divided along a second substantial center line substantially perpendicular to the pair of opposing sides. 
     
     
         10 . The piezoelectric device according to  claim 5 , wherein the supporting part is configured to support all sides of the diaphragm, and
 a plurality of piezoelectric films are disposed along each side of all the sides of the diaphragm.   
     
     
         11 . The piezoelectric device according to  claim 1 , wherein
 the diaphragm is thinner at a center region thereof than a region thereof where the piezoelectric film is disposed.   
     
     
         12 . The piezoelectric device according to  claim 1 , wherein
 the piezoelectric film has a compressive stress, and   the upper electrode has a tensile stress.   
     
     
         13 . The piezoelectric device according to  claim 1 , wherein the supporting part includes a supporting part and an insulating layer. 
     
     
         14 . The piezoelectric device according to  claim 13 , wherein the insulating layer is adjacent the diaphragm. 
     
     
         15 . The piezoelectric device according to  claim 14 , wherein the insulating layer is silicon oxide. 
     
     
         16 . The piezoelectric device according to  claim 1 , further comprising a plurality of piezoelectric films adjacent the first surface of the diaphragm, the plurality of piezoelectric films being electrically coupled in parallel. 
     
     
         17 . The piezoelectric device according to  claim 1 , wherein the diaphragm has a substantially circular shape.