Saw filter having planar barrier layer and method of making

Abstract

Disclosed herein is a surface acoustic wave (SAW) filter and method of making the same. The SAW filter includes a piezoelectric substrate; a planar barrier layer disposed above the piezoelectric substrate, and at least one conductor buried in the piezoelectric substrate and the planar barrier layer.

What is claimed is: 
     
         1 . A method for making a surface acoustic wave (SAW) filter, the method comprising:
 depositing a planar barrier layer on a piezoelectric substrate;   patterning the planar barrier layer to form at least one trench;   depositing a metal layer above the planar barrier layer; and   polishing the metal layer to form at least one metal conductor.   
     
     
         2 . The method of  claim 1 , further comprising depositing an SiO 2  layer over the planar barrier layer and the at least one metal conductor. 
     
     
         3 . The method of  claim 1 , further comprising:
 after patterning the planar barrier layer, depositing a diffusion barrier layer,   wherein the diffusion barrier layer comprises one of TaN/Ta, TaSiN/Ta, WN/Ta, and WN/Ru, and   wherein the polishing further includes polishing the diffusion barrier layer.   
     
     
         4 . The method of  claim 1 , further comprising:
 after patterning the planar barrier layer, depositing an SiN cap layer;   wherein the polishing further comprises polishing the SiN cap layer, and   wherein a thickness of the at least one metal conductor is controlled by an amount of metal deposited.   
     
     
         5 . The method of  claim 1 , wherein the metal layer comprises copper (Cu), and wherein the method further comprises:
 depositing a TaN diffusion barrier layer above the at least one metal conductor;   depositing an Al conductor layer above the TaN diffusion barrier layer; and   patterning the TaN diffusion barrier layer and the Al conductor layer using a reactive ion etch to form at least one stacked conductor wherein the Al conductor layer is self-aligned with the TaN diffusion barrier layer.   
     
     
         6 . The method of  claim 1 ,
 wherein the metal layer comprises Cu, and   wherein the method further comprises:
 depositing a CoWP diffusion barrier layer above the at least one metal conductor; 
 depositing an Al conductor layer above the CoWP diffusion barrier layer; and 
 patterning the CoWP diffusion barrier layer and the Al conductor layer using a reactive ion etch to form at least one stacked conductor wherein the Cu conductor is self-aligned with the CoWP diffusion barrier layer. 
   
     
     
         7 . The method of  claim 1 ,
 wherein the metal layer comprises Cu, and   wherein the method further comprises:   after depositing the metal layer above the planar barrier layer, depositing a TaN diffusion barrier layer above the metal layer;   polishing the TaN diffusion barrier and the metal layer to form at least one recess;   depositing Al in the at least one recess; and   polishing the Al to form at least one self-aligned damascene stacked metal conductor.   
     
     
         8 . The method of  claim 7 , further comprising removing the planar barrier layer from the piezoelectric substrate. 
     
     
         9 . The method of  claim 7 , wherein a thickness of the Al is controlled by an amount of metal deposited. 
     
     
         10 . The method of  claim 1 , wherein the planar barrier layer comprises SiO 2 .