Electrostatic discharge protection for integrated circuit sensor passivation

• US 6,091,082 A
• Filed: 02/17/1998
• Issued: 07/18/2000
• Est. Priority Date: 02/17/1998
• Status: Expired due to Term

• Current Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Thomas, Danielle A., Bryant, Frank Randolph
• Primary Examiner(s): MINTEL, WILLIAM A
• Application Number:
  US09/024,094
• Time in Patent Office: 882 Days
• Field of Search: 257/651, 257/637, 257/77, 257/644, 257/640, 257/641, 382/4, 382/124, 382/312, 340/825.34
• US Class Current: 257/77
• CPC Class Codes: G06V 40/1329 Protecting the fingerprint sensor against damage caused by the finger
• CPC Class Codes: Y10S 438/931 Silicon carbide semiconductor
• CPC Class Codes: Y10S 438/953 Making radiation resistant device
• CPC Class Codes: Y10S 438/958 Passivation layer

Abstract

A structure and method for creating an integrated circuit passivation (24) comprising, a circuit (16), a dielectric (18), and metal plates (20) over which an insulating layer (26) is disposed that electrically and hermetically isolates the circuit (16), and a discharge layer (32) that is deposited to form a passivation (24) that protects the circuit (16) from electrostatic discharges caused by, e.g., a finger, is disclosed.

Claims

1. An integrated circuit comprising:

sensor circuitry; and

a passivation comprising;

an insulating layer disposed over the sensor circuitry to electrically isolate the sensor circuitry; and

a conductive discharge layer disposed over the insulating layer, wherein the discharge layer diffuses electrostatic charges to electronic components that dissipate the electrostatic charges if the passivation is contacted.

2. The integrated circuit of claim 1, wherein the insulating layer comprises glass.

3. The integrated circuit of claim 1, wherein the insulating layer comprises silicon oxide.

4. The integrated circuit of claim 1, further comprising:

a silicon nitride layer disposed over the insulating layer;

a silicon carbide layer disposed over the silicon nitride layer; and

wherein the discharge layer comprises SiC_x, and wherein x is less than 1.

5. The integrated circuit of claim 1, wherein the discharge layer is doped.

6. The integrated circuit of claim 1, wherein the insulating layer is doped.

7. The integrated circuit of claim 1, wherein the discharge layer comprises SiC_x, where x is less than 1.

8. The integrated circuit of claim 1, wherein the discharge layer comprises SiN_x, where x is less than 1.

9. The integrated circuit of claim 1, further comprising:

a silicon carbide layer disposed over a silicon nitride layer; and

wherein the discharge layer comprises SiC_x, wherein x is less than 1.

10. The integrated circuit of claim 1, further comprising:

a silicon carbide layer disposed over the silicon nitride layer; and

a discharge layer, wherein the discharge layer is SiN_x, wherein x is less than 1.

11. The integrated circuit of claim 1, wherein the insulating layer comprises silicon nitride.

12. The integrated circuit of claim 1, wherein the discharge layer comprises a mixture of silicon carbide and SiC_x, wherein x is less than 1.

13. The integrated circuit of claim 1, wherein the discharge layer comprises a mixture of silicon carbide and SiN_x, wherein x is less than 1.

14. The integrated circuit of claim 1, wherein said passivation comprises part of a fingerprint sensor.

15. A capacitance-coupled fingerprint sensor comprising:

sensor circuitry; and

a passivation comprising;

an insulating layer disposed over the sensor circuitry to electrically isolate the sensor circuitry; and

a conductive discharge layer disposed over the insulating layer, wherein the discharge layer diffuses electrostatic charges to electronic components that dissipate the electrostatic charges if a finger touches the passivation, the discharge layer having a hardness greater than that of silicon nitride.

16. The fingerprint sensor of claim 15, wherein the insulating layer comprises glass.

17. The fingerprint sensor of claim 15, wherein the insulating layer comprises silicon oxide.

18. The fingerprint sensor of claim 15, further comprising:

a silicon nitride layer disposed over the insulating layer;

a silicon carbide layer disposed over the silicon nitride layer; and

a silicon-carbon layer wherein the stoichiometry of carbon to silicon is less than 1.

19. The fingerprint sensor of claim 15, wherein the discharge layer is doped.

20. The fingerprint sensor of claim 15, wherein the insulating layer is doped.

21. The fingerprint sensor of claim 15, wherein the discharge layer comprises SiC_x, where x is less than 1.

22. The fingerprint sensor of claim 15, wherein the discharge layer comprises SiN_x, where x is less than 1.

23. The fingerprint sensor of claim 15, further comprising:

a silicon carbide layer disposed over the silicon nitride layer; and

a silicon-carbon layer wherein the stoichiometry of carbon to silicon is less than 1.

24. The fingerprint sensor of claim 15, further comprising:

a silicon carbide layer;

a silicon nitride layer; and

a silicon-nitride layer wherein the stoichiometry of nitrogen to silicon is less than 1.

25. The fingerprint sensor of claim 15, wherein the insulating layer comprises silicon nitride.

26. The fingerprint sensor of claim 15, wherein the discharge layer comprises a mixture of silicon carbide and SiC_x, wherein x is less than 1.

27. The fingerprint sensor of claim 15, wherein the discharge layer comprises a mixture of silicon nitride and SiN_x, wherein x is less than 1.

28. The fingerprint sensor of claim 15, wherein the discharge layer is formed as a mixture of silicon carbide and SiC_x, wherein in an early part of the deposition x is 1, and in a later part of the deposition the x is less than 1.

29. The fingerprint sensor of claim 15, wherein the discharge layer is formed as a mixture of silicon nitride and SiN_x, wherein in an early part of the deposition x is 1, and in a later part of the deposition the x is less than 1.

30. An integrated circuit passivation on a fingerprint sensor integrated circuit, the passivation comprising:

a conductive discharge layer disposed over the fingerprint sensor circuitry, wherein the discharge layer diffuses electrostatic charges to electronic components that dissipate the electrostatic charges if a finger touches the passivation.

31. The passivation of claim 30 wherein the discharge layer comprises a doped material.

32. The passivation claim 30, further comprising a mechanical protection layer.

33. The passivation of claim 30 wherein the discharge layer includes a mechanical protection layer.