Semiconductor device-based sensors and methods associated with the same

• US 20050285155A1
• Filed: 06/28/2004
• Published: 12/29/2005
• Est. Priority Date: 06/28/2004
• Status: Active Grant

• Current Assignee: MACOM Technology Solutions Holdings, Inc.
• Original Assignee: Nitronex Corporation
• Inventors: Piner, Edwin L., Linthicum, Kevin J., Johnson, Jerry W.
• Granted Patent: US 7,361,946 B2
• Time in Patent Office: Days
• US Class Current: 257/253
• CPC Class Codes: G01N 27/129 Diode type sensors, e.g. gas sensitive Schottky diodes capacitor type sensors G01N27/227; field-effect transistor type sensors G01N27/414
• 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 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

Semiconductor device-based chemical sensors and methods associated with the same are provided. The sensors include regions that can interact with chemical species being detected. The chemical species may, for example, be a component of a fluid (e.g., gas or liquid). The interaction between the chemical species and a region of the sensor causes a change in a measurable property (e.g., an electrical property) of the device. These changes may be related to the concentration of the chemical species in the medium being characterized.

Claims

1. A FET-based chemical sensor designed to detect a chemical species comprising:

a semiconductor material region;

a source electrode formed on the semiconductor material region;

a drain electrode formed on the semiconductor material region;

a gate electrode formed on the semiconductor material region; and

a sensing region, separated from the gate electrode, and capable of interacting with the chemical species to change a measurable property of the chemical sensor.

2. The sensor of claim 1, wherein the sensing region comprises a sensing layer.

3. The sensor of claim 2, wherein the sensing layer has a thickness of less than 500 nm.

4. The sensor of claim 2, wherein the sensing region further comprises a surface region of the semiconductor material region positioned under the sensing layer.

5. The sensor of claim 1, wherein the sensing region comprises an exposed surface region of the semiconductor material region.

6. The sensor of claim 1, wherein the sensing region is formed between the source electrode and the drain electrode.

7. The sensor of claim 1, wherein a ratio of sensing electrode surface area to total channel surface area is greater than 0.35.

8. The sensor of claim 1, wherein the sensing region comprises a sensing electrode.

9. The sensor of claim 8, wherein a separate voltage may be applied to each of the source, drain, gate and sensing electrodes.

10. The sensor of claim 1, wherein respective electrical contacts to each of the source, drain, gate and sensing electrodes are formed on a backside of the sensor.

11. The sensor of claim 1, wherein the sensor is substantially free of electrical contacts on a frontside of the sensor in areas separate from the sensing region.

12. The sensor of claim 1, wherein the semiconductor region comprises a gallium nitride material layer.

13. The sensor of claim 12, wherein the sensing region is formed, at least in part, in the gallium nitride material layer.

14. The sensor of claim 12, wherein the gallium nitride material layer has a crack level of less than about 0.005 micron/micron².

15. The sensor of claim 1, further comprising a substrate.

16. The sensor of claim 15, wherein the substrate is a silicon substrate.

17. The sensor of claim 15, further comprising a compositionally-graded transition layer formed between the substrate and the semiconductor material region.

18. The sensor of claim 1, further comprising an electrode-defining layer that defines, in part, the gate electrode and the sensing region.

19. The sensor of claim 1, further comprising a second sensing region.

20. The sensor of claim 19, wherein the sensing region is formed on a first side of the sensor and the second sensing region is formed on a second side of the sensor.

21. The sensor of claim 1, wherein the chemical species is a gaseous species.

22. The sensor of claim 1, wherein the interaction between the chemical species and the sensing region results in a change in the drain current of the sensor.

23. The sensor of claim 1, wherein the interaction between the chemical species and the sensing region changes the surface potential of the semiconductor material region.

24. The sensor of claim 1, wherein the chemical species is adsorbed by the sensing region during operation.

25. A FET-based chemical sensor designed to detect a chemical species comprising:

a silicon substrate;

a transition layer formed on the silicon substrate;

a gallium nitride material region formed on the transition layer;

a source electrode formed on the gallium nitride material region;

a drain electrode formed on the gallium nitride material region;

a gate electrode formed on the gallium nitride material region; and

a sensing region, separate from the gate electrode, and capable of interacting with the chemical species to change a drain current of the chemical sensor.

26. A semiconductor device-based chemical sensor comprising:

a semiconductor material region;

a sensing electrode formed on the semiconductor material region and separated from electrodes needed for conventional operation of the device, the sensing electrode capable of interacting with the chemical species to change a measurable property of the chemical sensor.

27. The sensor of claim 26, wherein the chemical sensor is a FET-based sensor and the electrodes needed for conventional operation of the device include a source electrode, a drain electrode and a gate electrode.

28. The sensor of claim 26, wherein the chemical sensor is a Schottky diode-based sensor and the electrodes needed for conventional operation of the device include an ohmic electrode and a Schottky electrode.

29. A semiconductor device-based chemical sensor comprising:

a semiconductor material region;

a first electrode formed on the semiconductor material region;

a second electrode formed on the semiconductor material region;

a first electrical contact extending from a backside of the sensor to the first electrode;

a second electrical contact extending from a backside of the sensor to the second electrode; and

a sensing region, separated from the first electrode and the second electrode, and capable of interacting with the chemical species to change a measurable property of the chemical sensor.

30. The chemical sensor of claim 29, further comprising a third electrode, wherein the first electrode is a source electrode, the second electrode is a drain electrode and the third electrode is a gate electrode.

31. A method of detecting chemical species comprising:

exposing a FET-based chemical sensor to a medium comprising chemical species; and

measuring changes in drain current of the sensor resulting from adsorption of the chemical species on a sensing region separated from the gate electrode to detect chemical species.

32. The method of claim 31, wherein the sensing region comprises a sensing layer.

33. The method of claim 32, wherein the sensing layer has a thickness of less than 500 nm.

34. The method of claim 32, wherein the sensing region further comprises a surface region of the semiconductor material region positioned under the sensing layer.

35. The method of claim 31, wherein the sensing region comprises an exposed surface region of the semiconductor material region.

36. The method of claim 31, wherein the sensing region comprises a sensing electrode.

37. The method of claim 36, wherein a separate voltage may be applied to each of the source, drain, gate and sensing electrodes.

38. The method of claim 31, wherein the sensing region is formed, at least in part, in a gallium nitride material layer.

39. The method of claim 31, wherein the chemical species is a gaseous species.