Patent ID: 7408287
Filing Date: 2008-08-05
Classification: H03H

Abstract:
1. A film bulk acoustic wave resonator filter including a plurality of film bulk acoustic wave resonators comprising: a substrate having a plurality of cavities; an underlayer formed on said substrate to cover said cavities; a bottom electrode layer formed on top of said underlayer; a piezoelectric layer formed on top of said bottom electrode layer; and a top electrode layer formed on top of said piezoelectric layer, wherein the underlayer thickness in a first region where a first resonator of said plurality of resonators is formed differs from the underlayer thickness in a second region where a second resonator of said plurality of resonators is formed, wherein the underlayer has a top surface and a bottom surface, the bottom electrode layer being formed on the top surface of the underlayer, and wherein the top surface of the underlayer is planar.