Metal oxide sensors and method of forming

• US 7,208,327 B2
• Filed: 05/25/2005
• Issued: 04/24/2007
• Est. Priority Date: 05/25/2005
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Dubin, Valery M., Gstrein, Florian
• Primary Examiner(s): NGUYEN, CUONG QUANG
• Application Number:
  US11/136,585
• Publication Number:
  US 20060267051A1
• Time in Patent Office: 699 Days
• Field of Search: 438 3- 17
• US Class Current: 438/10
• 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

Abstract

A metal oxide sensor is provided on a semiconductor substrate to provide on-chip sensing of gases. The sensor may include a metal layer that may have pores formed by lithography to be of a certain width. The top metal layer may be oxidized resulting in a narrowing of the pores. Another metal layer may be formed over the oxidized layer and electrical contacts may be formed on the metal layer. The contacts may be coupled to a monitoring system that receives electrical signals indicative of gases sensed by the metal oxide sensor.

Claims

1. A method of forming a metal oxide sensor comprising:

depositing a metal layer on a semiconductor substrate;

forming nanostructures within the metal layer;

oxidizing the metal layer to form a metal oxide semiconductor;

depositing a metallic layer on the metal oxide semiconductor; and

forming gas sensor contacts on the deposited metallic layer.

2. The method of claim 1, wherein forming the nanostructures comprises using lithography and etching to form the nanostructures.

3. The method of claim 1, wherein the nanostructures comprise pores.

4. The method of claim 1, wherein the nanostructures comprise tubes.

5. The method of claim 1, wherein the nanostructures have a width of approximately 10–

200 nm.

6. The method of claim 1, wherein depositing the metallic layer comprises providing a metal layer using a plating technique.

7. The method of claim 1, wherein the metal layer deposited on the semiconductor substrate comprises one of tungsten, titanium, nickel, tin, zinc, tantalum and molybdenum.

8. The method of claim 1, further comprising forming an oxidized layer over the semiconductor substrate prior to depositing the metal layer.

9. The method of claim 1, further comprising attaching electric leads to the contacts.

10. The method of claim 9, further comprising sensing gas vapors using the metal oxide sensor having the gas sensor contacts.

11. A method comprising:

depositing a metal layer;

lithographically forming nanostructures within the metal layer;

forming a metal oxide semiconductor on the metal layer;

depositing a metallic layer on the metal oxide semiconductor; and

forming electrical contacts on the metallic layer.

12. The method of claim 11, wherein the metal layer comprises one of tungsten, titanium, nickel, tin, zinc, tantalum and molybdenum.

13. The method of claim 11, further comprising monitoring gas vapors based on signals received from the electrical contacts.