Chemical sensor with consistent sensor surface areas

• US 10,422,767 B2
• Filed: 06/05/2017
• Issued: 09/24/2019
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Life Technologies Corporation (Thermo Fisher Scientific Incorporated)
• Original Assignee: Life Technologies Corporation (Thermo Fisher Scientific Incorporated)
• Inventors: Fife, Keith G., Owens, Jordan, Li, Shifeng, Bustillo, James
• Primary Examiner(s): Nguyen, Thinh T
• Application Number:
  US15/614,589
• Publication Number:
  US 20180128773A1
• Time in Patent Office: 841 Days
• Field of Search: 438 49, 438 66, 438201, 438211, 438257, 257253, 257315
• CPC Class Codes: B01L 2200/0668 Trapping microscopic beads
• CPC Class Codes: B01L 2300/0636 Integrated biosensor, microarrays
• CPC Class Codes: B01L 2300/0877 Flow chambers
• CPC Class Codes: B01L 3/502761 specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads, for physically stretching molecules investigating characteristics of particles G01N15/00
• CPC Class Codes: G01N 27/414 Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
• CPC Class Codes: G01N 27/4145 specially adapted for biomolecules, e.g. gate electrode with immobilised receptors
• CPC Class Codes: G01N 27/4148 Integrated circuits therefor, e.g. fabricated by CMOS processing CMOS processing per se H01L21/82
• CPC Class Codes: H01L 29/40114 the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure

Abstract

A chemical sensor is described. The chemical sensor includes a chemically-sensitive field effect transistor including a floating gate conductor having an upper surface. A material defines an opening extending to the upper surface of the floating gate conductor, the material comprising a first dielectric underlying a second dielectric. A conductive element contacts the upper surface of the floating gate conductor and extending a distance along a sidewall of the opening.

Claims

1. A method for manufacturing a chemical sensor, the method comprising:

forming a chemically-sensitive field effect transistor including a floating gate conductor having an upper surface;

forming a first dielectric on the floating gate conductor;

etching the first dielectric to define a cavity extending to the upper surface of the floating gate conductor;

depositing a second dielectric thereon;

etching the second dielectric to expose the upper surface of the floating gate conductor, thereby defining an opening, a width at an upper portion of the opening being greater than a width at a lower portion of the opening; and

forming a conductive element within the opening, the conductive element contacting the upper surface of the floating gate conductor and extending a distance along a sidewall of the opening.

2. The method of claim 1, wherein forming the conductive element within the opening comprises:

depositing a conductive material within the opening and on an upper surface of the first dielectric; and

removing at least a portion of the conductive material from the upper surface of the second dielectric.

3. The method of claim 2, wherein removing at least the portion of the conductive material comprises:

depositing a layer of photoresist within the opening; and

removing at least a portion of the conductive material together with the photoresist from the upper surface of the second dielectric.

4. The method of claim 3, further comprising removing remaining photoresist.

5. The method of claim 1, wherein the conductive material element comprises titanium.

6. The method of claim 1, wherein the opening is a nanowell.

7. The method of claim 1, wherein the forming a conductive element includes depositing a conductive material conformally within the opening.

8. The method of claim 1, wherein the conductive element includes an inner surface defining a lower portion of a reaction region for the chemical sensor, and the second dielectric includes an inner surface defining an upper portion of the opening.

9. The method of claim 3, wherein removing at least a portion of the conductive material together with the photoresist includes removing conductive material to exposes a sidewall of the opening.

10. The method of claim 1, wherein etching the first dielectric to define a cavity includes etching to leave a portion of the first dielectric to extend over the floating gate conductor.

11. The method of claim 1, wherein the first dielectric includes an oxide of silicon.

12. The method of claim 1, wherein the second dielectric includes a nitride of silicon.

13. The method of claim 1, wherein the conductive element includes titanium nitride.

14. The method of claim 1, further comprising growing a titanium oxide or oxynitride over the titanium nitride.

15. The method of claim 1, further comprising growing an oxide over the conductive element.

16. The method of claim 1, wherein the lower portion of the opening is defined by the first dielectric.

17. The method of claim 1, wherein the upper portion of the opening is defined by the second dielectric.

18. The method of claim 1, wherein etching the second dielectric includes etching a portion of the first dielectric.

19. The method of claim 1, wherein the conductive element includes a metallic material or alloy thereof.

20. The method of claim 1, wherein the conductive element includes a ceramic material selected from the group consisting of titanium nitride, titanium aluminum nitride, tantalum nitride, and a combination thereof.