Manufacturing process for thin film bulk acoustic resonator (FBAR) filters

Abstract

Method for fabricating an acoustical resonator on a substrate having a top surface. First, a depression in said top surface is generated. Next, the depression is filled with a sacrificial material. The filled depression has an upper surface level with said top surface of said substrate. Next, a first electrode is deposited on said upper surface. Then, a layer of piezoelectric material is deposited on said first electrode. A second electrode is deposited on the layer of piezoelectric material using a mass load lift-off process.

1 - 16 . (canceled)  
     
     
         17 . An acoustical resonator comprising: 
 a buffer layer;    a first electrode formed on the buffer layer;    a second electrode formed with a lift-off process; and    a layer of piezoelectric material sandwiched between said first and second electrodes.    
     
     
         18 . The acoustical resonator of  claim 17  wherein said first electrode comprises molybdenum.  
     
     
         19 . The acoustical resonator of  claim 17  wherein said layer of piezoelectric material comprises AlN.  
     
     
         20 . The acoustical resonator of  claim 17  further comprising a substrate having a cavity in a surface thereof, said first electrode bridging said cavity.