Piezoelectric device, process for producing the same, and liquid discharge device

Abstract

A piezoelectric device includes a substrate; and a laminated film formed above the substrate. The laminated film includes a lower electrode layer, a piezoelectric layer, and an upper electrode layer formed in this order, and the lower electrode layer is a metal electrode layer containing as one or more main components one or more nonnoble metals and/or one or more nonnoble alloys. Preferably, the one or more main components are one or more of the metals Cr, W, Ti, Al, Fe, Mo, In, Sn, Ni, Cu, Co, and Ta, and alloys of the metals.

1 . A piezoelectric device comprising:
 a substrate; and   a laminated film being formed above said substrate, and including,
 a lower electrode layer, 
 a piezoelectric layer formed on said lower electrode layer, and 
 an upper electrode layer formed on said piezoelectric layer; 
   wherein said lower electrode layer is a metal electrode layer containing as one or more main components one or more of nonnoble metals and nonnoble alloys.   
     
     
         2 . A piezoelectric device according to  claim 1 , wherein said lower electrode layer contains as one or more main components one or more of metals Cr, W, Ti, Al, Fe, Mo, In, Sn, Ni, Cu, Co, and Ta, and alloys of the metals. 
     
     
         3 . A piezoelectric device according to  claim 2 , wherein said lower electrode layer contains as one or more main components one or more of iron and alloys of iron. 
     
     
         4 . A piezoelectric device according to  claim 1 , wherein said lower electrode layer is formed by vapor phase epitaxy. 
     
     
         5 . A piezoelectric device according to  claim 3 , wherein said lower electrode layer is formed by vapor phase epitaxy. 
     
     
         6 . A piezoelectric device according to  claim 1 , wherein said lower electrode layer is patterned by use of wet etching. 
     
     
         7 . A piezoelectric device according to  claim 3 , wherein said lower electrode layer is patterned by use of wet etching. 
     
     
         8 . A piezoelectric device according to  claim 1 , wherein said piezoelectric layer is formed of a perovskite oxide, and is (100) oriented. 
     
     
         9 . A piezoelectric device according to  claim 3 , wherein said piezoelectric layer is formed of a perovskite oxide, and is (100) oriented. 
     
     
         10 . A piezoelectric device according to  claim 1 , wherein said piezoelectric layer has spontaneous polarization with a negatively-polarized side and a positively-polarized side, the negatively-polarized side of the spontaneous polarization is oriented toward the lower electrode layer, the positively-polarized side of the spontaneous polarization is oriented toward the upper electrode layer, said upper electrode layer realizes a grand electrode to which a fixed voltage is applied, said lower electrode layer is separated into address electrodes, and variable voltages are applied to the address electrodes. 
     
     
         11 . A piezoelectric device according to  claim 3 , wherein said piezoelectric layer has spontaneous polarization with a negatively-polarized side and a positively-polarized side, the negatively-polarized side of the spontaneous polarization is oriented toward the lower electrode layer, the positively-polarized side of the spontaneous polarization is oriented toward the upper electrode layer, said upper electrode layer realizes a grand electrode to which a fixed voltage is applied, said lower electrode layer is separated into address electrodes, and variable voltages are applied to the address electrodes. 
     
     
         12 . A piezoelectric device according to  claim 10 , further comprising a driver which drives said address electrodes so as to vary the voltages applied to the address electrodes. 
     
     
         13 . A piezoelectric device according to  claim 11 , further comprising a driver which drives said address electrodes so as to vary the voltages applied to the address electrodes. 
     
     
         14 . A piezoelectric device according to  claim 10 , wherein said piezoelectric layer is formed at 400° C. to 600° C. 
     
     
         15 . A piezoelectric device according to  claim 11 , wherein said piezoelectric layer is formed at 400° C. to 600° C. 
     
     
         16 . A piezoelectric device according to  claim 14 , wherein said piezoelectric layer is formed by vapor phase epitaxy using plasma under a condition that the difference between a floating potential and a plasma potential in plasma generated during formation of the piezoelectric layer is 10 to 35 V. 
     
     
         17 . A piezoelectric device according to  claim 15 , wherein said piezoelectric layer is formed by vapor phase epitaxy using plasma under a condition that the difference between a floating potential and a plasma potential in plasma generated during formation of the piezoelectric layer is 10 to 35 V. 
     
     
         18 . A piezoelectric device according to  claim 14 , wherein said piezoelectric layer is formed under a condition satisfying inequalities,
   −0.2 Ts+ 100 <Vs−Vf≦− 0.2 Ts+ 130, and     10 ≦Vs−Vf≦ 35,   
       where Ts represents in degrees centigrade a value of film-formation temperature, and Vs−Vf represents in volts a difference between a floating potential and a plasma potential in plasma generated during formation of the piezoelectric layer. 
     
     
         19 . A piezoelectric device according to  claim 15 , wherein said piezoelectric layer is formed under a condition satisfying inequalities,
   −0.2 Ts+ 100 <Vs−Vf≦− 0.2 Ts+ 130, and     10 ≦Vs−Vf≦ 35,   
       where Ts represents in degrees centigrade a value of film-formation temperature, and Vs−Vf represents in volts a difference between a floating potential and a plasma potential in plasma generated during formation of the piezoelectric layer. 
     
     
         20 . A process for producing said piezoelectric device according to  claim 1 , comprising the steps of:
 (a) forming a first film for said lower electrode layer;   (b) patterning said first film;   (c) forming a second film for said piezoelectric layer; and   (d) patterning said second film.   
     
     
         21 . A process for producing according to  claim 20 , wherein said step (b) and said step (d) are concurrently performed after said step (a) and said step (c) are performed. 
     
     
         22 . A process for producing according to  claim 21 , wherein said step (b) and said step (d) are performed by use of wet etching. 
     
     
         23 . A liquid discharge device comprising:
 said piezoelectric device according to  claim 1 ; and   a discharge member being formed integrally with or separately from said substrate in the piezoelectric device, and including,
 a liquid-reserve chamber which reserves liquid, and 
 a liquid-discharge outlet through which said liquid is externally discharged from the liquid-reserve chamber.