Piezoelectric thin-film element and a manufacturing method thereof

Abstract

To provide a piezoelectric thin-film element small in leak current between electrode metal films and its manufacturing method are presented, the piezoelectric thin-film element comprises at least one unit laminated body composed of a piezoelectric thin-film having mutually facing first surface and second surface, a first electrode metal film on the first surface, and a second electrode metal film on the second surface, in which an electrode separation surface composed of a piezoelectric thin-film surface parallel to the first surface is provided between the first electrode metal film and second electrode metal film.

What is claimed is:  
     
         1 . A piezoelectric thin-film element comprising at least one unit laminated body composed of a piezoelectric thin-film having a first surface and a second surface opposed each other, a first electrode metal film on said first surface and a second electrode metal film on said second surface, 
 wherein said unit laminated body has an electrode separation surface between said first electrode metal film and said second electrode metal film, said electrode separation surface being parallel to said first surface.    
     
     
         2 . The piezoelectric thin-film element according to  claim 1 , 
 wherein said electrode separation surface is a step portion disposed at the side face of said piezoelectric thin-film.    
     
     
         3 . The piezoelectric thin-film element according to  claim 1 , 
 wherein said electrode separation surface is an outer circumferential portion of said second surface positioned outside of said second electrode metal film.    
     
     
         4 . The piezoelectric thin-film element as in one of claims  1 - 3 , 
 wherein a width of said electrode separation surface is set to be 0.1 μm or more.    
     
     
         5 . A piezoelectric thin-film element comprising; 
 a first unit laminated body composed of a first piezoelectric thin-film having a first surface and a second surface opposed each other, a first electrode metal film on said first surface and a second electrode film on said second surface, and    a second unit laminated body composed of a second piezoelectric thin-film having a third surface and a fourth surface opposed each other, a third electrode metal film on said third surface and a fourth electrode film on said fourth surface, said first unit laminated body and said second unit laminated body being bonded to each other, with said second electrode metal film and said third electrode metal film opposite to each other,    wherein said first unit laminated body has a first electrode separation surface between said first electrode metal film and said second electrode metal film, said first electrode separation surface being parallel to said first surface,    wherein said second unit laminated body has a second electrode separation surface between said third electrode metal film and said fourth electrode metal film, said second electrode separation surface being parallel to said first surface.    
     
     
         6 . The piezoelectric thin-film element according to  claim 5 , 
 wherein said second electrode metal film and said third electrode metal film are bonded by an insulating adhesive layer, and said second electrode metal film and said third electrode metal film are connected by using a through-hole formed in said adhesive layer.    
     
     
         7 . The piezoelectric thin-film element according to  claim 6 , 
 wherein said through-hole is formed in a recess provided by removing said fourth electrode metal film and said second piezoelectric thin-film so as to reach up to said third electrode metal film, said recess having an electrode separation surface parallel to said third surface at the inner circumferential side face of said second piezoelectric thin-film.    
     
     
         8 . The piezoelectric thin-film element according to  claim 6 , 
 wherein said through-hole is formed in a notch provided by removing said fourth electrode metal film and said second piezoelectric thin-film so as to reach up to said third electrode metal film, said notch having an electrode separation surface parallel to said third surface at the side face of the second piezoelectric thin-film.    
     
     
         9 . An actuator comprising a pair of piezoelectric elements expanding and contracting in mutually parallel directions, each of said piezoelectric elements comprising; 
 a first unit laminated body composed of a first piezoelectric thin-film having a first surface and a second surface opposed each other, a first electrode metal film on said first surface and a second electrode film on said second surface, and    a second unit laminated body composed of a second piezoelectric thin-film having a third surface and a fourth surface opposed each other, a third electrode metal film on said third surface and a fourth electrode film on said fourth surface, said first unit laminated body and said second unit laminated body being bonded to each other, with said second electrode metal film and said third electrode metal film opposite to each other,    wherein each of said first unit laminated bodies has a first electrode separation surface between said first electrode metal film and said second electrode metal film, said first electrode separation surface being parallel to said first surface,    wherein each of said second unit laminated bodies has a second electrode separation surface between said third electrode metal film and said fourth electrode metal film, said second electrode separation surface being parallel to said first surface.    
     
     
         10 . The actuator according to  claim 9 , 
 wherein said second electrode metal film and said third electrode metal film are bonded by an insulating adhesive layer, and said second electrode metal film and said third electrode metal film are connected by using a through-hole formed in said adhesive layer.    
     
     
         11 . The actuator element according to  claim 10 , 
 wherein said through-hole is formed in a recess provided by removing said fourth electrode metal film and said second piezoelectric thin-film so as to reach up to said third electrode metal film, said recess having an electrode separation surface parallel to said third surface at the inner circumferential side face of said second piezoelectric thin-film.    
     
     
         12 . The actuator according to  claim 10 , 
 wherein said through-hole is formed in a notch provided by removing said fourth electrode metal film and said second piezoelectric thin-film so as to reach up to said third electrode metal film, said notch having an electrode separation surface parallel to said third surface at the side face of said second piezoelectric thin-film.    
     
     
         13 . The actuator according to  claim 10 , 
 wherein it is designed to connect between an electrode metal film for connecting said second electrode metal film and said third electrode metal film formed in said through-hole in one of the pair of piezoelectric element, and an electrode metal film for connecting said second electrode metal film and said third electrode metal film formed in said through-hole in the other piezoelectric element.    
     
     
         14 . A method of piezoelectric thin-film element by processing a laminated body laminating a lower electrode metal film, a piezoelectric thin-film, and an upper electrode metal film into a specified shape by dry etching, which comprises 
 a first etching step of forming a first mask of a specified shape on the upper electrode metal film, and dry etching until the piezoelectric thin-film side is exposed to the outside of the first mask, and    a second etching step of removing the first mask, forming a second mask so as to cover the upper electrode metal film processed in the above specified shape by extending to part of the piezoelectric thin-film around the upper electrode metal film, and removing the piezoelectric thin-film and lower electrode metal film positioned outside of the second mask by dry etching.    
     
     
         15 . The method of piezoelectric thin-film element according to  claim 14;   wherein in said first etching step, said piezoelectric thin-film is removed up to the middle in the thickness direction by etching.    
     
     
         16 . A method of piezoelectric thin-film element by processing a laminated body composed of two unit laminated bodies, each laminating a first electrode metal film, a piezoelectric thin-film, and a second electrode metal film, being bonded through an adhesive layer so that the second electrode metal film of one unit laminated body may be opposite to the first electrode metal film of other unit laminated body, into a specified shape by dry etching, in which 
 a lower etching step of processing the first electrode metal film into a specified shape is provided, aside from an upper etching step of processing the second electrode metal film into a specified shape,    when processing each unit laminated body, and    the lower etching step is characterized by forming a mask for on the second electrode metal film and part of the piezoelectric thin-film exposed to its periphery, and removing the piezoelectric thin-film and first electrode metal film positioned outside of the mask.    
     
     
         17 . The method of piezoelectric thin-film element according to  claim 16;   wherein said lower etching step of processing the first electrode metal film of said other unit laminated body and said upper etching step of processing the second electrode metal film of said one unit laminated body are a continuous etching process by using a same mask.