EXTENDED GATE SENSOR FOR pH SENSING

Abstract

A sensing device includes a substrate having a source region and a drain region formed therein. A gate structure is formed over the substrate and includes a gate dielectric and a gate conductor. The gate conductor is formed on the gate dielectric and disposed between the source region and the drain region. A dielectric layer is formed over the substrate and has a depth configured to form a well over the gate conductor. A gate extension is formed in contact with or as part of the gate conductor and including a conductive material covering one or more surfaces of the well.

1 . A sensing device, comprising:
 a substrate having a source region and a drain region formed therein;   a gate structure formed over the substrate and including a gate dielectric and a gate conductor, the gate conductor being formed on the gate dielectric and disposed between the source region and the drain region;   a dielectric layer formed over the substrate and having a depth configured to form a well over the gate conductor; and   a gate extension formed in contact with or part of the gate conductor and including a conductive material exposed on one or more surfaces of the well.   
     
     
         2 . The sensing device as recited in  claim 1 , wherein the gate extension includes a plate and the plate is exposed on a bottom surface of the well. 
     
     
         3 . The sensing device as recited in  claim 1 , wherein the gate extension includes a u-shape and the u-shape is exposed on a bottom and side walls of the well. 
     
     
         4 . The sensing device as recited in  claim 1 , wherein the gate extension includes a u-shape and the u-shape is exposed on a bottom and a portion of side walls of the well. 
     
     
         5 . The sensing device as recited in  claim 1 , wherein the sensing device is configured to measure pH of a fluid in the well. 
     
     
         6 . The sensing device as recited in  claim 1 , wherein the conductive material includes one of TiN, TaN and Pt. 
     
     
         7 . The sensing device as recited in  claim 1 , wherein the gate extension and the gate conductor are formed from a same material. 
     
     
         8 . The sensing device as recited in  claim 1 , wherein the gate extension forms a cup-like structure. 
     
     
         9 . A sensing device, comprising:
 a substrate having a source region and a drain region formed therein;   a gate dielectric formed over the substrate;   a dielectric layer formed over the substrate and having a depth configured to form a well over a region between the source region and the drain region; and   a gate extension formed in contact with the gate conductor and extending laterally outward parallel to a major surface of the substrate, the gate extension including a conductive material exposed on at least one surface of the well and forming a gate conductor of the sensing device.   
     
     
         10 . The sensing device as recited in  claim 9 , wherein the gate extension includes a plate and the plate is exposed on a bottom surface of the well. 
     
     
         11 . The sensing device as recited in  claim 9 , wherein the gate extension includes a u-shape and the u-shape is exposed on a bottom and side walls of the well. 
     
     
         12 . The sensing device as recited in  claim 9 , wherein the gate extension includes a u-shape and the u-shape is exposed on a bottom and a portion of side walls of the well. 
     
     
         13 . The sensing device as recited in  claim 9 , wherein the sensing device is configured to measure pH of a fluid in the well. 
     
     
         14 . The sensing device as recited in  claim 9 , wherein the conductive material includes one of TiN, TaN and Pt. 
     
     
         15 . The sensing device as recited in  claim 9 , wherein the gate extension and the gate conductor are formed from a same material. 
     
     
         16 . The sensing device as recited in  claim 9 , wherein the gate extension forms a cup-like structure. 
     
     
         17 .- 20 . (canceled)