Tungsten hot wire current limiter for ESD protection

• US 6,700,164 B1
• Filed: 07/07/2000
• Issued: 03/02/2004
• Est. Priority Date: 07/07/2000
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Duncan, Kevin A., Voldman, Steven H., Tonti, William R., Brennan, Ciaran J.
• Primary Examiner(s): Lee, Eddie
• Assistant Examiner(s): NGUYEN, JOSEPH H
• Application Number:
  US09/611,812
• Time in Patent Office: 1,334 Days
• Field of Search: 257/379, 257/355, 257/358, 257/363, 361/91.1, 361/91.2, 361/93.7, 361/56, 361/58
• US Class Current: 257/379
• CPC Class Codes: H01L 23/62 Protection against overvoltage, e.g. fuses, shunts
• 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: H01L 2924/3011 Impedance

Abstract

In order to divert damaging currents into an electrostatic discharge (ESD) protection device during an ESD event, a tungsten wire resistor is incorporated into a current path connected in parallel with the ESD protection circuitry. The tungsten wire resistor has linear current-voltage (IV) characteristics at low currents, and non-linear IV characteristics at high current levels. The width and length of the resistor is chosen so that the resistor experiences significant self-heating caused by the higher currents generated by the ESD event. At a higher current level, the resistor becomes hot and its resistance increases dramatically. As a result the voltage drop across it increases thus diverting excess current into the parallel connected ESD protection circuitry. This limits the current through the resistor and thereby protects circuit elements in series with the resistor.

Claims

1. A circuit comprising:

a first terminal;

a second terminal;

an electrostatic discharge (ESD) network serially coupled between said first terminal and said second terminal; and

a resistance device and a circuit to be protected connected in series and coupled between said first terminal and said second terminal in parallel with said ESD network,

wherein said resistance device has a resistance that increases with heating of said resistance device.

2. The circuit as recited in claim 1, further comprising:

a substrate having electronic circuitry formed thereon; and

said resistance device comprising a dielectric layer on the substrate having interconnect wiring therein for interconnecting the electronic circuitry, the interconnect wiring including a metal wire whose resistance increases in response to increasing current there through self-heating wherein the increasing current is diverted from traveling through the metal wire.

3. The circuit as described in claim 1, wherein said resistance device has a resistance that increases with heating to increase a resistance value for diverting current into the ESD network and away from said circuit to be protected.

4. The circuit as described in claim 1, wherein said resistance device heats in response to increasing current through said device so it is self-heating.

5. The circuit as recited in claim 4, wherein said self-heating resistance device comprises a tungsten wire.

6. The circuit as recited in claim 4, wherein said self-heating resistance device comprises a material having a positive thermal coefficient of resistance.

7. The circuit as recited in claim 4, wherein the circuit to be protected is on an integrated circuit chip and wherein said increasing current is caused by an electrostatic discharge (ESD) event on said integrated circuit chip.

8. The circuit as described in claim 1, wherein said resistance device comprises a metal wire, and

a self-heating resistance device connected in parallel with said ESD network between said first terminal and said second terminal,

wherein said resistance device heats in response to increasing current to increase a resistance value for diverting the increasing current into the ESD network.

9. The circuit as recited in claim 8, wherein the metal wire comprises a positive thermal coefficient of resistance.

10. The circuit as recited in claim 9, wherein the metal wire is made from a metal selected from the group consisting of tungsten, tantalum and titanium.

11. The circuit as recited in claim 9, wherein the metal wire is made from a metal selected from the group consisting of nitrides of tungsten, tantalum and titanium.

12. The circuit of claim 1, wherein the ESD network comprises three serially connected components.

13. The circuit of claim 12, wherein the ESD network includes at least two diodes.

14. The circuit of claim 12, wherein the ESD network includes a transistor serially connected between two diodes.

15. An electrostatic discharge (ESD) protection device, comprising:

a first terminal;

a second terminal;

an electrostatic discharge (ESD) network serially coupled between said first terminal and said second terminal; and

a self-heating resistance and an ESD sensitive circuit coupled between said first terminal and said second terminal in parallel with said ESD network,

wherein said resistance device heats in response to increasing current to increase a resistance value for diverting the increasing current into the ESD network and away from the ESD sensitive circuit.

16. The electrostatic discharge (ESD) protection device as recited in claim 15, wherein said self-heating resistance device comprises a tungsten wire.

17. The electrostatic discharge (ESD) protection device as recited in claim 15, wherein said self-heating resistance device is made from a metal selected from the group consisting of tungsten, tantalum, titanium and nitrides thereof.

18. A circuit comprising:

a first terminal;

a second terminal;

an electrostatic discharge (ESD) network serially-connected between said first terminal and said second terminal; and

a self-heating resistance device coupled between said first terminal and said second terminal in a parallel path with said ESD network,

wherein said resistance device exhibits linear current-voltage (IV) characteristics at low currents, and non-linear IV characteristics at high current levels to increase a resistance value to divert electrostatic discharge to said ESD network.

19. The circuit as recited in claim 18, wherein said self-heating resistance device comprises a tungsten wire.

20. The circuit as recited in claim 18, wherein said self-heating resistance device comprises a material having a positive thermal coefficient of resistance.