Metal-to-metal via-type antifuse

• US 5,962,910 A
• Filed: 07/17/1997
• Issued: 10/05/1999
• Est. Priority Date: 10/04/1995
• Status: Expired due to Term

• Current Assignee: Microsemi SoC Corp. (Microchip Technology Incorporated)
• Original Assignee: Actel Corporation (Microchip Technology Incorporated)
• Inventors: Hawley, Frank W., Eltoukhy, Abdelshafy A., McCollum, John L.
• Primary Examiner(s): WALLACE, VALENCIA MARTIN
• Application Number:
  US08/895,723
• Time in Patent Office: 810 Days
• Field of Search: 257/50, 257/209, 257/529, 257/530, 438/68, 438/600, 438/61, 438/131, 438/467
• US Class Current: 257/530
• CPC Class Codes: H01L 23/5252 comprising anti-fuses, i.e. connections having their state changed from non-conductive to conductive
• 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

Abstract

A metal-to-metal antifuse disposed between two aluminum metallization layers in a CMOS integrated circuit or similar structure includes an antifuse material layer having a substantially aluminum-free conductive link. The substantially aluminum-free link is formed by forming a first barrier metal layer out of TiN having a first thickness, a second barrier metal layer out of TiN having a second thickness which may be less than said first thickness, the first and second barrier metal layers separating the antifuse material layer from first and second electrodes. The antifuse is programmed by applying a voltage potential capable of programming the antifuse across the electrodes with the more positive side of the potential applied to the electrode adjacent the barrier metal layer having the least thickness. In another aspect of the invention, an antifuse having a first barrier metal layer of a first thickness and a second barrier metal layer of a second thickness may be fabricated wherein the first thickness is less than the second thickness and wherein programming of the antifuse is accomplished by placing the more positive voltage of the programming voltage supply on the electrode of the antifuse adjacent the first barrier metal layer.

Claims

1. A programmed antifuse disposed in an integrated circuit comprising:

a lower conductive layer formed of a film of material including aluminum;

a lower barrier metal layer disposed over and in electrical contact with said lower conductive layer, said lower barrier metal layer formed of TiN and having a first minimum thickness of greater than 2000 Å

;

an antifuse material layer disposed over and in contact with said lower barrier metal layer;

an upper barrier metal layer disposed over and in contact with said antifuse material layer, said upper barrier metal layer formed of TiN and having a second minimum thickness, said second minimum thickness being in the range of 1000 Å

-2000 Å

;

an upper conductive layer formed of a film of material including aluminum, said film disposed over and in electrical contact with said upper barrier metal layer; and

a conductive link located within said antifuse material layer and electrically connecting said lower barrier metal layer and said upper barrier metal layer, said conductive link comprising substantially no aluminum metal.

2. A programmed antifuse according to claim 1 wherein said conductive link comprises less than 1% aluminum by weight.

7. An antifuse according to claim 1 disposed in a semiconductor device over an active transistor region.

8. An antifuse according to claim 2 disposed in a semiconductor device over an active transistor region.

3. A programmed antifuse comprising:

a lower electrode formed of a film of material including aluminum;

a lower barrier metal layer disposed over and in electrical contact with said lower conductive layer, said lower barrier metal layer formed of TiN and having a first minimum thickness in the range of 1000 Å

to 2000 Å

;

an antifuse material layer disposed over and in contact with said lower barrier metal layer;

an upper barrier metal layer disposed over and in contact with said antifuse material layer, said upper barrier metal layer formed of TiN and having a second minimum thickness, said second minimum thickness being at least 1000 Å and

said first minimum thickness being greater than said second thickness;

an upper electrode formed of a film of material including aluminum, said film disposed over and in electrical contact with said upper barrier metal layer; and

a conductive link located within said antifuse material layer and electrically connecting said lower barrier metal layer and said upper barrier metal layer, said conductive link comprising substantially no aluminum metal.

4. A programmed antifuse according to claim 3 wherein said conductive link comprises less than 1% aluminum by weight.

9. An antifuse according to claim 3 disposed in a semiconductor device over an active transistor region.

10. An antifuse according to claim 4 disposed in a semiconductor device over an active transistor region.

5. An antifuse comprising:

a lower conductive layer formed of a film of material including aluminum;

a lower barrier metal layer disposed over and in electrical contact with said lower conductive layer, said lower barrier metal layer formed of TiN and having a first minimum thickness of greater than 2000 Å

;

an antifuse material layer disposed over and in contact with said lower barrier metal layer;

an upper barrier metal layer disposed over and in contact with said antifuse material layer, said upper barrier metal layer formed of TiN and having a second minimum thickness, said second minimum thickness being in the range of 1000 Å

-2000 Å

;

an upper conductive layer formed of a film of material including aluminum, said film disposed over and in electrical contact with said upper barrier metal layer; and

programming means for programming the antifuse, said programming means including a power supply capable of applying;

a first programming signal between said lower conductive layer and said upper conductive layer for a first period of time, a voltage induced on said upper conductive layer referenced to said lower conductive layer being positive;

a second programming signal between said lower conductive layer and said upper conductive layer for a second period of time after said first period of time, a voltage induced on said lower conductive layer referenced to said upper conductive layer being negative and the amplitude of said voltage being less than the amplitude of said voltage applied in said first programming signal;

a third programming signal for a third period of time after said second period of time, said third programming signal equivalent to said first programming signal; and

a fourth programming signal for a fourth period of time after said third period of time, said fourth programming signal equivalent to said second programming signal.

11. An antifuse according to claim 5 disposed in a semiconductor device over an active transistor region.

16. A programmed antifuse according to claim 5 wherein said conductive link comprises less than 1% aluminum by weight.

18. A programmed antifuse according to claim 11 wherein said conductive link comprises less than 1% aluminum by weight.

6. An antifuse comprising:

a lower conductive layer formed of a film of material including aluminum;

a lower barrier metal layer disposed over and in electrical contact with said lower conductive layer, said lower barrier metal layer formed of TiN and having a first minimum thickness in the range of 1000 Å

-2000 Å

;

an antifuse material layer disposed over and in contact with said lower barrier metal layer;

an upper barrier metal layer disposed over and in contact with said antifuse material layer, said upper barrier metal layer formed of TiN and having a second minimum thickness, said second minimum thickness being greater than 2000 Å

;

an upper conductive layer formed of a film of material including aluminum, said film disposed over and in electrical contact with said upper barrier metal layer; and

programming means for programming the antifuse, said programming means including a power supply capable of applying;

a first programming signal between said lower conductive layer and said upper conductive layer for a first period of time, a voltage induced on said upper conductive layer referenced to said upper conductive layer being positive;

a second programming signal between said lower conductive layer and said upper conductive layer for a second period of time after said first period of time, a voltage induced on said upper conductive layer referenced to said upper conductive layer being negative and the amplitude of said voltage being less than the amplitude of said voltage applied in said first programming signal;

a third programming signal for a third period of time after said second period of time, said third programming signal equivalent to said first programming signal; and

a fourth programming signal for a fourth period of time after said third period of time, said fourth programming signal equivalent to said second programming signal.

12. An antifuse according to claim 6 disposed in a semiconductor device over an active transistor region.

17. A programmed antifuse according to claim 6 wherein said conductive link comprises less than 1% aluminum by weight.

13. An unprogrammed antifuse disposed in an integrated circuit comprising:

a lower conductive layer formed of a film of material including aluminum;

a lower barrier metal layer disposed over and in electrical contact with said lower conductive layer, said lower barrier metal layer formed of TiN and having a first minimum thickness of greater than 2000 Å

;

an antifuse material layer disposed over and in contact with said lower barrier metal layer;

an upper barrier metal layer disposed over and in contact with said antifuse material layer, said upper barrier metal layer formed of TiN and having a second minimum thickness, said second minimum thickness being in the range of 1000 Å

-2000 Å

;

an upper conductive layer formed of a film of material including aluminum, said film disposed over and in electrical contact with said upper barrier metal layer; and

said unprogrammed antifuse designed to be programmed by applying a programming signal between said lower conductive layer and said upper conductive layer, a voltage induced on said lower conductive layer referenced to said lower conductive layer being positive, such that said programming signal induces metal from said lower barrier metal later and said upper barrier metal later into said antifuse material layer, forming a conductive link between said lower barrier metal layer and said upper barrier metal layer, said conductive link containing substantially no aluminum.

14. An unprogrammed antifuse disposed in an integrated circuit comprising:

a lower conductive layer formed of a film of material including aluminum;

a lower barrier metal layer disposed over and in electrical contact with said lower conductive link, said lower barrier metal layer formed of TiN and having a first minimum thickness in the range of about 1000 Å

to about 2000 Å

;

an antifuse material layer disposed over and in contact with said lower barrier metal layer;

an upper barrier metal layer disposed over and in contact with said antifuse material layer, said upper barrier metal layer formed of TiN and having a second minimum thickness of greater than 2000 Å

; and

an upper conductive layer formed of a film of material including aluminum, said film disposed over and in electrical contact with said upper barrier metal layer; and

said unprogrammed antifuse designed to be programmed by applying a programming signal between said lower conductive layer and said upper conductive layer, a voltage induced on said lower conductive layer referenced to said upper conductive layer being positive, such that said programming signal induces metal from said lower barrier metal later and said upper barrier metal later into said antifuse material layer, forming a conductive link within said antifuse material layer electrically connecting said lower barrier metal layer and said upper barrier metal layer, said conductive link containing substantially no aluminum.

15. An unprogrammed antifuse disposed in an integrated circuit comprising:

a lower conductive layer formed of a film of material including aluminum;

a lower barrier metal layer disposed over and in electrical contact with said lower conductive layer, said lower barrier metal layer formed of TiN and having a first minimum thickness of at least about 2000 Å

;

an antifuse material layer disposed over and in contact with said lower barrier metal layer;

an upper barrier metal layer disposed over and in contact with said antifuse material layer, said upper barrier metal layer formed of TiN and having a second minimum thickness greater than 2000 Å

, said second minimum thickness being greater than said first minimum thickness; and

an upper conductive layer formed of a film of material including aluminum, said film disposed over and in electrical contact with said upper barrier metal layer; and

said unprogrammed antifuse designed to be programmed by applying either (1) a programming signal between said lower conductive layer and said upper conductive layer, a voltage induced on said lower conductive layer referenced to said lower conductive layer being positive, such that said programming signal induces metal from said lower barrier metal later and said upper barrier metal later into said antifuse material layer, forming a conductive link between said lower barrier metal layer and said upper barrier metal layer, said conductive link containing substantially no aluminum, or (2) a programming signal between said lower conductive layer and said upper conductive layer, a voltage induced on said lower conductive layer referenced to said upper conductive layer being positive, such that said programming signal induces metal from said lower barrier metal later and said upper barrier metal later into said antifuse material layer, forming a conductive link within said antifuse material layer electrically connecting said lower barrier metal layer and said upper barrier metal layer, said conductive link containing substantially no aluminum.