Apparatus and method for contacting a sensor conductive layer

• US 6,330,145 B1
• Filed: 12/30/1998
• Issued: 12/11/2001
• Est. Priority Date: 12/30/1998
• Status: Expired due to Term

• Current Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Thomas, Danielle A., Do-Bento-Vieira, Antonio A., Lepert, Arnaud Yves
• Primary Examiner(s): Leja, Ronald W.
• Application Number:
  US09/223,346
• Time in Patent Office: 1,077 Days
• Field of Search: 382/124, 382/312, 382/313, 324/661-663, 324/658, 361/220, 361/232, 361/233
• US Class Current: 361/220
• CPC Class Codes: G06V 40/1329 Protecting the fingerprint sensor against damage caused by the finger

Abstract

A structure and method is disclosed for grounding an electrostatic discharge device of an integrated circuit to dissipate electrostatic charges comprising an underlying dielectric layer disposed over capacitor plates of sensor circuitry and a conductive layer disposed over the underlying dielectric layer, wherein the conductive layer diffuses electrostatic charges at the surface of the integrated circuit to ground. The conductive material not only dissipates electrostatic charges to the ground, but may also protect at least a portion of the edge of the sensor chip from mechanical stress.

Claims

1. A portion of an integrated circuit package, comprising:

a sensor chip having

a dielectric layer over a plurality of conductive plates serving as capacitive sensor electrodes, the dielectric layer isolating the conductive plates, and

a conductive layer disposed over at least a portion of the dielectric layer and disposed over one or more conductive plates or regions between conductive plates, wherein the conductive layer dissipates an electrostatic charge in a manner that prevents the electrostatic charge from reaching the plurality of conductive plates, the conductive layer having a contact region between a central region of the sensor chip and a periphery of the sensor chip;

a support having a ground, the sensor chip being affixed to the support; and

a conductive material around a portion of the periphery of the sensor chip and contacting the contact region of the conductive layer, wherein the conductive material connects the conductive layer to the support ground.

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

a passivation layer overlying the conductive layer and having an opening therethrough exposing the contact region of the conductive layer.

3. The integrated circuit of claim 1, wherein the sensor chip comprises a fingerprint sensor chip.

4. The integrated circuit of claim 1, wherein the support has pads that are electrically connected to the conductive layer of the sensor chip, at least one of the pads being a ground pad separate from the support ground.

5. The integrated circuit of claim 2, wherein the opening through the passivation layer extends around the portion of the periphery of the sensor chip to form a trench,

wherein the conductive material extends, around the portion of the periphery of the sensor chip, from a surface of the support around a side of the sensor chip over a portion of the passivation layer between the trench and the side of the sensor chip and into the trench.

6. A portion of an integrated circuit, comprising:

a sensor chip having

a dielectric layer over a plurality of conductive plates serving as capacitive sensor electrodes, and

a conductive layer disposed over at least a portion of the dielectric layer and disposed over one or more conductive plates, wherein the conductive layer dissipates an electrostatic charge, preventing the electrostatic charge from reaching the plurality of conductive plates,

a passivation layer disposed over at least a portion of the dielectric layer and the conductive layer, the passivation having an opening therethrough between a central region of the sensor chip and a periphery of the sensor chip which exposes

a portion of the conductive layer;

a support having a ground, the sensor chip being affixed to the support; and

a conductive material around a portion of the periphery of the sensor chip and contacting the exposed portion of the conductive layer, electrically connecting the conductive layer of the sensor chip and the ground of the support.

7. The integrated circuit of claim 6 wherein the conductive material comprises a conductive epoxy.

8. The integrated circuit of claim 6 wherein the conductive material comprises a conductive polymer.

9. The integrated circuit of claim 6, wherein the conductive material comprises a metal.

10. The integrated circuit of claim 6, wherein the sensor chip comprises a fingerprint sensor chip having a ground for the sensors.

11. The integrated circuit of claim 7, wherein the support has pads that are electrically connected to the sensor chip, at least one of the pads being a ground pad separate from the sensor chip support ground.

12. The integrated circuit of claim 6, wherein the conductive material is disposed along the periphery on at least three sides of the sensor chip.

13. The integrated circuit of claim 6, wherein the conductive material is disposed along substantially all of the periphery of the sensor chip.

14. The integrated circuit of claim 6, wherein the conductive material is disposed surrounding the periphery of the sensor chip.

15. The integrated circuit of claim 6, wherein the conductive material provides mechanical protection to the portion of the periphery of the sensor chip along which the conductive material is disposed.

16. The integrated circuit of claim 6, wherein the passivation layer is disposed over all of the dielectric layer and all of the conductive layer, and wherein the conductive layer is disposed over the dielectric layer and substantially over the conductive plates.

17. The integrated circuit of claim 6, wherein the conductive layer and passivation layer are substantially planar.

18. The integrated circuit of claim 6, wherein the conductive layer has a sheet resistance low enough to adequately dissipate the electrostatic charge.

19. The integrated circuit of claim 6, wherein the conductive layer comprises aluminum.

20. The integrated circuit of claim 6, wherein the conductive layer has a thickness of between approximately 5,000 to 15,000 angstroms.

21. The integrated circuit of claim 6, wherein the conductive layer has a resistivity of approximately 0.04 ohms per square.

22. The integrated circuit of claim 6, wherein the conductive layer comprises titanium.

23. The integrated circuit of claim 22, wherein the conductive layer has a thickness of between approximately 500 to 1,000 angstroms.

24. The integrated circuit of claim 6, wherein the conductive layer has a resistivity of approximately 10 ohms per square.

25. The integrated circuit of claim 6, wherein the conductive layer comprises tungsten.

26. The integrated circuit of claim 25, wherein the conductive layer has a thickness of between approximately 4,000 to 8,000 angstroms.

27. The integrated circuit of claim 25, wherein the conductive layer has a resistivity of approximately 0.14 ohms per square.

28. A method of grounding an electrostatic discharge device of an integrated circuit comprising:

forming a protective layer over a plurality of conductive plates serving as capacitive sensor electrodes, the protective layer isolating the conductive plates and protecting the conductive plates from damage, wherein the protective layer comprises a dielectric region underlying a conductive layer having an exposed portion between a central region of the integrated circuit which comprises a sensor chip in which the conductive plates are formed and a periphery of the sensor chip; and

depositing a conductive material around a portion of the periphery of the sensor chip and contacting the exposed portion of the conductive layer, connecting the conductive layer of the sensor chip to a ground, wherein the conductive layer dissipates electrostatic charges through the ground.

29. The method of claim 28, wherein the sensor chip is affixed to a support having the ground.

30. The method of claim 29, wherein the conductive layer is electrically connected to the support ground, which is separate from a ground for sensor cells within the sensor chip.

31. The method of claim 28, wherein the conductive material comprises a conductive epoxy.

32. The method of claim 28, wherein the conductive material comprises a conductive polymer.

33. The method of claim 28, wherein the conductive material comprises a metal.

34. The method of claim 28, wherein the sensor chip comprises a fingerprint sensor chip.