Multi-band filter module and method of fabricating the same

Abstract

A multi-band filter module and a method of fabricating the same are provided. The multi-band filter module includes a piezoelectric substrate, a first filter provided on the piezoelectric substrate, and a second filter provided adjacent to the first filter on the piezoelectric substrate, and operating in a frequency band that is lower than that of the first filter.

1 . A method of fabricating a multi-band filter module, the method comprising:
 (a) forming a Film Bulk Acoustic Resonator (FBAR) on a piezoelectric substrate; and   (b) forming a Surface Acoustic Wave (SAW) device on the piezoelectric substrate;   wherein the steps (a) and (b) are concurrently performed.   
   
   
       2 . The method of  claim 1 , wherein step (a) comprises: (a   1   ) forming a sacrificial layer, wherein the sacrificial layer is used to form an air gap to be recessed on a surface of the piezoelectric substrate;
 (a   2   ) sequentially depositing a first electrode, a piezoelectric plate, and a second electrode, on the piezoelectric substrate to form a resonant part;   (a   3   ) depositing an electrode pad, which connects to the first and second electrodes; and   (a   4   ) removing the sacrificial layer to form the air gap corresponding to the resonant part.   
   
   
       3 . The method of  claim 2 , wherein step (b) comprises:
 (b1) patterning the SAW device on the piezoelectric substrate; and   (b   2   ) forming a SAW pad to be connected to the SAW device.   
   
   
       4 . The method of  claim 3 , wherein step (b1) is performed at the same time as when the first electrode is formed in the (a   2   ). 
   
   
       5 . The method of  claim 4 , wherein step (b   2   ) is performed concurrent with the step (a   3   ). 
   
   
       6 . he method of  claim 3 , wherein step (b   2   ) is performed concurrent with step (a   3   ).