BAW Gyroscope with Bottom Electrode

Abstract

A bulk acoustic wave gyroscope has a primary member in a member plane, and an electrode layer in an electrode plane spaced from the member plane. The electrode layer has a first portion that is electrically isolated from a second portion. The first portion, however, is mechanically coupled with the second portion and faces the primary member (e.g., to actuate or sense movement of the primary member). For support, the second portion of the electrode is directly coupled with structure in the member plane.

What is claimed is: 
     
         1 . A method of forming a bulk acoustic wave gyroscope, the method comprising:
 forming a primary member in a member plane;   forming an electrode layer in an electrode plane that is spaced from the member plane;   removing a portion of the electrode layer to form a trench; and   filling the trench with a non-conductive material to produce a first portion of the electrode layer and a second portion of the electrode layer, the non-conductive material mechanically connecting the first portion of the electrode layer and the second portion of the electrode layer, the nonconductive material electrically isolating the first portion of the electrode layer from the second portion of the electrode layer, the second portion being separate from the primary member and stabilizing the electrode layer.   
     
     
         2 . The method as defined by  claim 1 , further comprising forming an anchor through the second portion of the electrode layer and into structure in the member plane. 
     
     
         3 . The method as defined by  claim 1 , wherein forming the primary member and forming the electrode layer comprises processing a silicon-on-insulator wafer. 
     
     
         4 . The method as defined by  claim 1 , further comprising releasing the primary member to form a space between the primary member and the electrode layer. 
     
     
         5 . The method as defined by  claim 4 , wherein releasing comprises timing the release to maintain insulator material between the member plane and the electrode plane. 
     
     
         6 . The method as defined by  claim 1 , further comprising:
 forming a conductive path extending from the member plane and into the second portion of the electrode layer.   
     
     
         7 . The method as defined by  claim 6 , wherein forming the conductive path comprises:
 forming a via.   
     
     
         8 . The method as defined by  claim 7 , wherein the via includes doped polysilicon. 
     
     
         9 . The method as defined by  claim 1 , wherein the second portion of the electrode layer is grounded. 
     
     
         10 . The method as defined by  claim 1 , wherein the first portion of the electrode layer is configured to actuate movement of the primary member. 
     
     
         11 . The method as defined by  claim 10 , wherein the first portion of the electrode layer is configured to actuate a flexural mode of the primary member. 
     
     
         12 . The method as defined by  claim 1 , wherein the first portion of the electrode layer is configured to sense movement of the primary member. 
     
     
         13 . The method as defined by  claim 12 , wherein the first portion of the electrode layer is configured to sense a flexural mode of the primary member. 
     
     
         14 . The method as defined by  claim 1 , further comprising:
 forming a side electrode in the member plane, the side electrode being radially spaced from the primary member.   
     
     
         15 . The method as defined by  claim 14 , wherein the side electrode is configured to actuate movement of the primary member. 
     
     
         16 . The method as defined by  claim 15 , wherein the side electrode is configured to actuate a bulk mode of the primary member. 
     
     
         17 . The method as defined by  claim 14 , wherein the side electrode is configured to sense movement of the primary member. 
     
     
         18 . The method as defined by  claim 17 , wherein the side electrode is configured to sense a bulk mode of the primary member.