CHEMICAL SENSING AND/OR MEASURING DEVICES AND METHODS

• US 20120161207A1
• Filed: 11/22/2010
• Published: 06/28/2012
• Est. Priority Date: 11/23/2009
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: HOMYK, Andrew P., Henry, Michael D., Scherer, Axel, Walavalkar, Sameer
• Granted Patent: US 9,018,684 B2
• Time in Patent Office: Days
• US Class Current: 257/253
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: G01N 27/4146 involving nanosized elements, e.g. nanotubes, nanowires
• CPC Class Codes: H01L 29/0676 oriented perpendicular or at an angle to a substrate
• CPC Class Codes: H01L 29/66666 Vertical transistors H01L29/66712, H01L29/66742 take precedence
• CPC Class Codes: H01L 29/775 with one dimensional charge carrier gas channel, e.g. quantum wire FET

Abstract

Methods for fabricating silicon nanowire chemical sensing devices, devices thus obtained, and methods for utilizing devices for sensing and measuring chemical concentration of selected species in a fluid are described. Devices may comprise a metal-oxide-semiconductor field-effect transistor (MOSFET) structure.

Claims

1. A device comprising:

a semiconductor substrate with a planar surface;

a semiconductor nanopillar on the semiconductor substrate and substantially perpendicular to the planar surface;

an insulating layer covering the semiconductor nanopillar;

a conductive layer covering the insulating layer, wherein the conductive layer and the insulating layer are devoid of an end portion thereof, thus exposing an uninsulated pillar end of the semiconductor nanopillar; and

a functional layer covering the conductive layer.

2. The device of claim 1, wherein the uninsulated pillar end forms an electrically contactable terminal and the functional layer forms a chemically contactable terminal.

3. The device of claim 1, wherein the functional layer is configured to attract a selected type of chemical species.

4. The device of claim 1, wherein the functional layer is configured to attract ions.

5. The device of claim 1, wherein the functional layer is a bilayer, the bilayer comprising:

an attractive layer for attracting a selected type of chemical species; and

a semi-permeable insulating layer, the semi-permeable insulating layer being on the attractive layer, wherein the semi-permeable insulating layer is configured to allow the selected type of chemical species to pass through and to insulate the attractive layer and the conductive layer of the device.

6. The device of claim 1, wherein the semiconductor nanopillar and the semiconductor substrate are made of silicon.

7. The device of claim 1, further comprising a conductive backside terminal coated on a backside of the semiconductor substrate, opposite the semiconductor nanopillar.

8. The device of claim 7, the device being a metal-oxide-semiconductor field-effect transistor (MOSFET) structure.

9. The device of claim 8, the conductive layer being a gate terminal of the MOSFET.

10. A microfluidic channel structure comprising one or more devices according to claim 1.

11. The device of claim 1, wherein the semiconductor nanopillar is a plurality of semiconductor nanopillars.

12. The device of claim 9, wherein the semiconductor substrate is a source or a drain of the MOSFET and the uninsulated pillar end is respectively the drain or the source of the MOSFET.

26. A method of measuring chemical species concentration comprising:

providing the device according to claim 1;

contacting a chemical-containing fluid with the device such that a selected type of chemical species in the chemical-containing fluid is suitable to be attracted by the chemical-attracting layer of the device;

forming a voltage difference between the uninsulated pillar end and the semiconductor substrate of the device; and

measuring a change in current flow between one or more of the uninsulated pillar end and the semiconductor substrate of the device, thus measuring the chemical species concentration.

27. The method of claim 26, wherein forming the voltage difference includes contacting the uninsulated pillar end with the chemical-containing fluid.

28. The method of claim 26, wherein the device is a first device, the method further comprising:

providing a second device;

measuring a change in current flow between the uninsulated pillar end and the semiconductor substrate of the second device;

obtaining a difference between the change in current flow (between the uninsulated pillar end and the semiconductor substrate) of the first device and the change in current flow (between the uninsulated pillar end and the semiconductor substrate) of the second device; and

comparing the difference to an ion-concentration model thus measuring the ion concentration.

29. The method of claim 27, wherein the first device comprises a plurality of pillars with a first interpillar distance and the second device comprises a plurality of pillars with a second interpillar distance different from the first interpillar distance.

30. The method of claim 26, wherein the device further comprising a plurality of semiconductor nanopillars.

31. The method of claim 26, wherein the device is within a microfluidic channel structure.

13. A device comprising:

a semiconductor substrate with a planar surface;

a semiconductor nanopillar on the semiconductor substrate and substantially perpendicular to the planar surface;

an insulating layer covering the semiconductor nanopillar wherein the insulating layer is devoid of an end portion thereof, thus exposing an uninsulated pillar end of the semiconductor nanopillar; and

a functional layer covering the insulating layer.

15. The method of claim 13, wherein the uninsulated pillar end forms an electrically contactable terminal and the chemical-attracting layer forms a chemically contactable terminal.

16. The method of claim 13, wherein the chemical-attracting layer is configured to attract a selected type of chemical species.

17. The method of claim 13, wherein the chemical-attracting layer is configured to attract ions.

18. The method of claim 13, wherein forming the chemical-attracting layer includes:

forming an attractive layer for attracting a selected type of chemical species; and

forming a semi-permeable insulating layer on the attractive layer wherein the semi-permeable insulating layer is configured to allow a selected type of chemical species to pass through and to insulate the attractive layer and the conductive layer of the device.

19. The method of claim 13, wherein the semiconductor nanopillar and the semiconductor substrate are made of silicon.

20. The method of claim 13, further comprising coating a backside terminal on the semiconductor substrate on a side opposite the nanopillar.

21. The method of claim 19, wherein the device forms a metal-oxide-semiconductor field-effect transistor (MOSFET) structure.

22. The method of claim 20, wherein the conductive layer forms a gate terminal of the MOSFET.

23. The method of claim 21, wherein the semiconductor substrate forms a source or a drain of the MOSFET and the uninsulated pillar end forms respectively the drain or the source of the MOSFET.

14. A method for fabricating a device, the method comprising:

providing a semiconductor substrate with a planar surface;

forming at least one semiconductor nanopillar on the semiconductor substrate and substantially perpendicular to the planar surface;

covering the semiconductor nanopillar with an insulating layer;

depositing a conductive layer on the insulating layer;

covering a portion of the conductive layer with a masking layer;

removing a conductive layer end of the conductive layer and an insulating layer end of the insulating layer, wherein the conductive layer end and the insulating layer end are not covered by the masking layer, thus exposing an uninsulated pillar end;

removing the masking layer; and

forming a chemical-attracting layer on the conductive layer, the chemical-attracting layer insulating the conductive layer.

24. The method of claim 14, wherein fabricating the device includes fabrication within one or more microfluidic channel structures.

25. The method of claim 14, wherein the semiconductor nanopillar is a plurality of semiconductor nanopillars