Chemical Coating of Microwell for Electrochemical Detection Device

Abstract

The described embodiments may provide a method of fabricating a chemical detection device. The method may comprise forming a microwell above a CMOS device. The microwell may comprise a bottom surface and sidewalls. The method may further comprise applying a first chemical to be selectively attached to the bottom surface of the microwell, forming a metal oxide layer on the sidewalls of the microwell, and applying a second chemical to be selectively attached to the sidewalls of the microwell. The second chemical may lack an affinity to the first chemical.

What is claimed is: 
     
         1 . A method of fabricating a chemical detection device, comprising:
 forming a microwell above a CMOS device, wherein the microwell comprises a bottom surface and sidewalls;   applying a first chemical to be selectively attached to the bottom surface of the microwell;   forming a metal oxide layer on the sidewalls of the microwell; and   applying a second chemical to be selectively attached to the sidewalls of the microwell, wherein the second chemical lacks an affinity to the first chemical.   
     
     
         2 . The method of  claim 1 , wherein the microwell comprises one or more top edges also covered by the metal oxide layer, wherein the metal oxide layer is a mono-molecular layer. 
     
     
         3 . The method of  claim 2 , wherein the metal oxide layer is coated by a neutral PEG phosphate or PEG phosphonate. 
     
     
         4 . The method of  claim 2 , wherein the metal oxide layer is a solvent based deposition of zirconium oxide (ZrO 2 ). 
     
     
         5 . The method of  claim 1 , wherein the second chemical comprises a silane group. 
     
     
         6 . The method of  claim 1 , wherein the first chemical comprises a phosphate, phosphonate, catechol, nitrocatechol, boronate, phenylboronate, imidazole, silanol. 
     
     
         7 . The method of  claim 1 , wherein the first chemical comprises a ph-sensing group. 
     
     
         8 . The method of  claim 1 , wherein the CMOS device comprises a charge-sensitive transistor having a floating gate terminal and the bottom surface of the microwell comprises a passivation layer on top of the floating gate terminal. 
     
     
         9 . A chemical detection device, comprising:
 a microwell having a bottom surface and sidewalls, the bottom surface being covered by a first chemical, the sidewalls being covered by a metal oxide layer and a second chemical on top of the metal oxide layer, wherein the second chemical lacks an affinity to the first chemical; and   a CMOS device placed underneath the bottom of the microwell.   
     
     
         10 . The chemical detection device of  claim 9 , wherein the CMOS device comprises a charge-sensitive transistor having a floating gate terminal. 
     
     
         11 . The chemical detection device of  claim 10 , wherein the bottom of the microwell comprises a passivation layer on top of the floating gate terminal. 
     
     
         12 . The chemical detection device of  claim 11 , wherein the passivation layer is a layer of metal oxide on top of one or more other layers of metal oxide. 
     
     
         13 . The chemical detection device of  claim 9 , wherein the first chemical comprises a phosphate, phosphonate, catechol, nitrocatechol, boronate, phenylboronate, imidazole, silanol, 
     
     
         14 . The chemical detection device of  claim 9 , wherein the first chemical comprises a pH-sensing group. 
     
     
         15 . The chemical detection device of  claim 9 , wherein the microwell has SiO 2  sidewalls. 
     
     
         16 . The chemical detection device of  claim 9 , wherein metal oxide layer covering the sidewalls is a mono-molecular layer. 
     
     
         17 . The chemical detection device of  claim 16 , wherein top edges of the microwell are also covered by the metal oxide layer. 
     
     
         18 . The chemical detection device of  claim 17 , wherein the metal oxide layer is a solvent based deposition of one of zirconium oxide (ZrO 2 ). 
     
     
         19 . The chemical detection device of  claim 9 , wherein the second chemical is a neutral PEG phosphate or PEG phosphonate. 
     
     
         20 . A method comprising:
 forming a microwell above a CMOS device, wherein the microwell comprises a bottom surface and sidewalls, and the microwell is configured to receive a solid phase support that has a plurality of analytes attached thereto;   applying a first chemical to be selectively attached to the bottom surface of the microwell;   forming a metal oxide layer on the sidewalls of the microwell; and   applying a second chemical to be selectively attached to the sidewalls of the microwell, wherein the second chemical lacks an affinity to the first chemical, wherein the CMOS device is configured to sense a charge at the bottom surface of the microwell due to one or more byproducts generated by at least one chemical reaction with the plurality of the analytes, wherein the one or more byproducts lack an affinity to the sidewalls of the microwell due to the second chemical.   
     
     
         21 . The method of  claim 20 , wherein the first chemical is positively charged prior to receiving the solid phase support to facilitate depositing of the solid phase support. 
     
     
         22 . The method of  claim 20 , wherein the solid phase support is one of: a microparticle, a nanoparticle, a bead, solid and porous comprising gels. 
     
     
         23 . The method of  claim 20 , wherein the plurality of analytes are multiple copies of a DNA sample.