Electrostatic discharge protection for integrated circuit sensor passivation

• US 6,472,246 B1
• Filed: 12/28/1999
• Issued: 10/29/2002
• 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): Nguyen, Tuan H.
• Assistant Examiner(s): BEREZNY, NEMA O
• Application Number:
  US09/473,365
• Time in Patent Office: 1,036 Days
• Field of Search: 438/64, 438/953, 438/958, 257/659, 257/660
• US Class Current: 438/64
• 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. A method of fabricating a fingerprint sensor passivation comprising the steps of:

assembling a sensor circuitry;

depositing an insulating layer on the sensor circuitry; and

depositing a discharge layer over the insulating layer, wherein the discharge layer diffuses electrostatic charges that are formed when the sensor is contacted.

2. The method of claim 1, further comprising the step of:

depositing a second insulating layer between the insulating layer and the discharge layer.

3. The method of claim 1, wherein the discharge layer is SiC_x, where x is less than 1.

4. The method of claim 1, wherein the discharge layer is SiN_x, where x is less than one.

5. The method of claim 1, wherein the step of depositing the discharge layer is further defined as comprising:

depositing a silicon carbide layer and the discharge layer concurrently, wherein the early part of the deposition has a silicon to carbon ratio of 1 and in the later part of the deposition the stoichiometry of carbon to silicon is less than 1.

6. The method of claim 1 wherein the step of depositing the discharge layer comprises:

depositing a silicon nitride layer having a stoichiometry ratio of nitrogen to silicon of 1;

modifying the stoichiometry ratio in a later part of the deposition having the stoichiometry of nitride to silicon being less than 1.

7. A method of fabricating a fingerprint sensor comprising the steps of:

assembling a sensor circuitry;

depositing an insulating layer on the sensor circuitry;

depositing a conductive discharge layer over the insulating layer; and

connecting the conductive discharge layer to electronic components to diffuse electrostatic charges to the electronic components.

8. The method of claim 7 wherein the electronic components dissipate the electrostatic charges.

9. A method of fabricating an integrated circuit comprising:

forming sensor input components;

depositing an insulating layer on the sensor input components; and

depositing a conductive layer over the insulating layer to diffuse electrostatic charges that are formed when the integrated circuit is contacted.

10. A method of protecting a fingerprint sensor from electrostatic charges comprising:

forming a fingerprint sensor circuitry;

depositing an insulating layer on the fingerprint sensor circuitry; and

depositing a conductive layer over the insulating layer to diffuse electrostatic charges that are formed when the integrated circuit is contacted by a finger.