Electrostatic discharge protection in integrated circuits, systems and methods

• US 5,640,299 A
• Filed: 07/18/1996
• Issued: 06/17/1997
• Est. Priority Date: 03/28/1991
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Leach, Jerald G.
• Primary Examiner(s): Gaffin, Jeffrey A.
• Assistant Examiner(s): Sherry, Michael J.
• Application Number:
  US08/683,293
• Time in Patent Office: 334 Days
• Field of Search: 361/56, 361/58, 361/91, 361/111
• US Class Current: 361/56
• CPC Class Codes: H01L 27/0251 for MOS devices
• CPC Class Codes: H01L 27/0259 using bipolar transistors as protective elements
• CPC Class Codes: H01L 27/0262 including a PNP transistor and a NPN transistor, wherein each of said transistors has its base coupled to the collector of the other transistor, e.g. silicon controlled rectifier [SCR] devices
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: Y10S 148/011 Bipolar transistors

Abstract

An integrated circuit has a semiconductor die with a substrate and at least first and second bond pads. An internal circuit is fabricated on the semiconductor die and connected to the first bond pad. An electrostatic discharge protection circuit including cascaded bipolar transistors is connected in series with a field effect transistor between the first and second bond pads. In another version, an output buffer of the integrated circuit is divided into sections. An electrostatic discharge protection circuit is triggerable in response to a voltage in the substrate. Resistive connections are provided from the sections of the output buffer to one of the bond pads. The output buffer is operative upon an electrostatic discharge event to inject sufficient charge into the substrate to produce the voltage to trigger the electrostatic discharge protection circuit. Other circuits, devices, systems and methods are also disclosed.

Claims

1. An electrostatic discharge protection circuit for use in an integrated circuit having processing circuitry on a substrate for operation of the integrated circuit, the electrostatic discharge protection circuit comprising:

a protection circuit with at least one device fabricated on said substrate and connected to a first bond pad to dissipate discharges into the substrate upon activation of the protection circuit;

a plurality of field effect transistors; and

a plurality of resistors wherein one of said resistors is connected between said protection circuit and a respective one of each of said plurality of field effect transistors to activate said protection circuit.

2. The circuit of claim 1 wherein the plurality of field effect transistors are connected to a second bond pad.

3. The circuit of claim 1 wherein said circuit comprises an SCR.

4. The circuit of claim 1 wherein each of said plurality of resistors comprise a diffusion resistor, a tank resistor, a silicided n-moat region or a polysilicon resistor.

5. The circuit of claim 1 wherein each of said plurality of resistors has a resistance value in the range of 10-100 ohms.

6. The circuit of claim 1 wherein said plurality of field effect transistors comprises at least four field effect transistors.

7. The circuit of claim 1 wherein said protection circuit comprises a bipolar transistor having an emitter connected to said first bond pad, a collector connected to said substrate, and a base connected to said plurality of resistors.

8. The circuit of claim 1 wherein each of the field effect transistors has a first and a second source/drain region having a gate there between, the first source/drain region connected to said respective one of said plurality of resistors, and the second source/drain region connected to a second bond pad, at least one of the field effect transistors operative to trigger the protection circuit for electrostatic discharge protection.

9. The circuit of claim 8 wherein said gate of each of said field effect transistors is connected to said second bond pad.

10. The circuit of claim 8 wherein at least two of said plurality of field effect transistors cooperate to trigger the protection circuit to prevent damage to any of said plurality of field effect transistors.

11. An integrated circuit comprising:

a substrate with bond pads;

a transistor having plural sections, each section being connected in parallel;

a plurality of resistors, each resistor connected between one of said sections and a first of said bond pads;

a protection circuit which is triggerable in response to a voltage in said substrate; and

said transistor operative upon an electrostatic discharge event to produce the voltage to trigger the protection circuit.

12. The integrated circuit of claim 11 wherein said protection circuit comprises an SCR.

13. The integrated circuit of claim 12 wherein said transistor has a CMOS structure on a low resistance substrate.

14. The integrated circuit of claim 11 wherein each section of said transistor has a first and a second source/drain region having a gate there between, said first source/drain region connected to one end of a respective one of said resistors, the other end of said resistor connected to said first bond pad and said second source/drain region connected to at least a second one of said bond pads other than said first bond pad, at least one of said sections operative to trigger said circuit for electrostatic discharge protection.

15. The integrated circuit of claim 14 wherein said transistor is an output buffer and said gate of each of said sections is connected to a signal line.

16. The integrated circuit of claim 14 wherein said gate of each of said sections is connected to said second one of said bond pads.

17. The integrated circuit of claim 11 wherein said protection circuit comprises an SCR.

18. The integrated circuit of claim 11 wherein each of said plurality of resistors comprise a diffusion resistor, a tank resistor, a silicided n-moat region or a polysilicon resistor.

19. The integrated circuit of claim 11 wherein each of said plurality of resistors has a resistance value in the range of 10-100 ohms.

20. The integrated circuit of claim 11 wherein said sectioned transistor comprises at least four sections.

21. The integrated circuit of claim 11 wherein at least two of said plurality of sections cooperate to trigger said protection circuit.