Electronic pH sensor die packaging

• US 8,536,626 B2
• Filed: 04/28/2011
• Issued: 09/17/2013
• Est. Priority Date: 04/28/2011
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Brown, Gregory C., Rahn, Curtis H.
• Primary Examiner(s): Nguyen, Cuong Q
• Assistant Examiner(s): Gebreyesus, Yosef
• Application Number:
  US13/096,710
• Publication Number:
  US 20120273845A1
• Time in Patent Office: 873 Days
• Field of Search: 257/253, 257/414, 204416-418, 204/403.01, 204/401.15, 204/433, 204/435, 324/438
• US Class Current: 257/253
• CPC Class Codes: G01N 27/414 Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
• CPC Class Codes: H01L 24/24 of an individual high density interconnect connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/1306 Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/1461 MEMS
• CPC Class Codes: H01L 2924/15787 Ceramics, e.g. crystalline carbides, nitrides or oxides

Abstract

A pH sensor is provided. The pH sensor comprises a substrate and an ion sensitive field effect transistor (ISFET) die comprising an ion sensing part that responds to pH, wherein the ISFET die is located over the substrate. The pH sensor also comprises a protective layer formed over at least a portion of an outer surface of the ISFET die and at least a portion of the substrate. Further, the pH sensor comprises a cover member mechanically coupled to the protective layer, wherein the cover member houses the ISFET die and the substrate, and wherein the cover member defines an opening proximate to the ion sensing part.

Claims

1. A pH sensor comprising:

a substrate including a base substrate and a cap formed over the base substrate;

an ion sensitive field effect transistor (ISFET) die comprising an ion sensing part that responds to pH, wherein the ISFET die is located over the substrate;

a protective layer formed over at least a first portion of an outer surface of the ISFET die and at least a portion of the substrate, wherein the protective layer is not formed over at least a second portion of the outer surface of the ISFET die;

a frit material formed at least partially in a sidewall region between the ISFET die and the cap, wherein the protective layer is formed over at least a portion of the frit material in the sidewall region and over at least a portion of the cap; and

a cover member mechanically coupled to the protective layer, wherein the cover member houses the ISFET die and the substrate, and wherein the cover member defines an opening proximate to the ion sensing part.

2. The pH sensor of claim 1, wherein a thermal coefficient of expansion of the ISFET die approximately matches a thermal coefficient of expansion of the frit material.

3. The pH sensor of claim 1, further comprising:

at least one wire, wherein a first end of the at least one wire is bonded to the ISFET die, wherein a portion of the wire is embedded in the frit material.

4. The pH sensor of claim 3, further comprising:

at least one electric pin, wherein a second end of the at least one wire is bonded to the at least one electric pin.

5. The pH sensor of claim 4, wherein the at least one wire is bonded to the at least one electric pin within a protective volume formed in the frit material.

6. The pH sensor of claim 1, further comprising:

an o-ring coupled between the protective layer and the cover member.

7. The pH sensor of claim 1, wherein the protective layer comprises a metal oxide, synthetic diamond, sapphire, or combinations thereof.

8. The pH sensor of claim 1, wherein the protective material comprises tantalum pentoxide, titanium oxide, silicon nitride, or combinations thereof.

9. The pH sensor of claim 1, further comprising:

a header, wherein the substrate is mounted to the header;

a reference electrode configured to provide a reference voltage; and

at least one electric pin coupled to the ISFET die via a wire, wherein the wire is at least partially embedded in the glass frit,

wherein the ISFET die is mounted to the substrate via the glass frit, and

wherein the ISFET die is configured such that when the ion sensing part of the ISFET die is exposed to a medium, the ion sensing part outputs a signal related to a pH level of the medium.

10. A sensor device comprising:

a substrate including a base substrate and a cap substrate formed over the base substrate;

a field effect transistor (FET) die mounted over the substrate via a frit material, wherein the frit material is formed at least partially in a sidewall region between the FET die and the cap substrate;

a protective layer formed over at least a first portion of an outer surface of the FET die, at least a portion of the frit material in the sidewall region, and at least partially over the cap substrate, wherein the protective layer is not formed over at least a second portion of the outer surface of the FET die; and

at least one wire that is bonded to the FET die at a first end, wherein at least a portion of the wire is embedded in the frit material.

11. The sensor device of claim 10, further comprising:

a cover member that houses the substrate, wherein the cover member defines an opening proximate to the FET die; and

an o-ring positioned between the cover member and the protective layer.

12. The sensor device of claim 11, wherein a portion of the protective layer and the second portion of outer surface of the FET die are exposed by the opening defined by the cover member.

13. The sensor device of claim 10, wherein the protective layer comprises tantalum pentoxide, titanium oxide, synthetic diamond, sapphire, silicon nitride, or combinations thereof.

14. The sensor device of claim 10, wherein the outer surface of the FET die is approximately flush with an outer surface of the cap substrate.

15. The sensor device of claim 10, wherein the protective layer comprises a non-porous material.