Piezoresistive sensing structure

Abstract

A piezoresistive sensing structure includes an assembly formed of a semiconductor material and including a cavity and a plurality of piezoresistive elements implanted into the assembly. The assembly includes a central mass coupled to a peripheral frame with a plurality of beams. Each beam is about 15 microns in width and includes one of the piezoresistive elements. The assembly may also include a first wafer having the cavity formed into a first side, and a second wafer with a plurality of beams formed in a first side. The second side of the second wafer is bonded to the first side of the first wafer.

1 . A piezoresistive sensing structure, comprising:
 an assembly including a cavity, wherein the assembly includes a semiconductor material; and   a plurality of piezoresistive elements implanted into the assembly, wherein the assembly includes a central mass that is coupled to a peripheral frame with a plurality of beams, and wherein a width of the beams is no greater than about 15 microns and each of the beams includes one of the elements.   
   
   
       2 . The structure of  claim 1 , wherein the assembly includes a first wafer having the cavity formed into a first side of the first wafer and a second wafer having a first side and a second side opposite the first side, wherein the second side of the second wafer is bonded to the first side of the first wafer. 
   
   
       3 . The structure of  claim 2 , wherein the second wafer is an N-type epitaxial wafer. 
   
   
       4 . The structure of  claim 3 , wherein the elements are P-type piezoresistive elements. 
   
   
       5 . The structure of  claim 2 , wherein the central mass and the beams are formed with a deep reactive ion etch (DRIE).