Antifuse structure suitable for VLSI application

• US 5,485,031 A
• Filed: 11/22/1993
• Issued: 01/16/1996
• Est. Priority Date: 11/22/1993
• Status: Expired due to Term

• Current Assignee: Actel Corporation (Microchip Technology Incorporated)
• Original Assignee: Actel Corporation (Microchip Technology Incorporated)
• Inventors: Hu, Chenming, Zhang, Guobiao, Chiang, Steve S.
• Primary Examiner(s): CARROLL, JAMES J
• Application Number:
  US08/156,612
• Time in Patent Office: 785 Days
• Field of Search: 257/530, 257/50, 257/751, 257/761, 257/763
• 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

The present invention relates to a high performance, high reliability antifuse using conductive electrodes. The problem of switch-off of the programmed antifuses is solved by reducing the thermal conductivity of the conductive electrodes. This is achieved by using lower thermal conductivity conductors for the electrodes or by using thinner electrodes to increase thermal resistance. According to a first aspect of the present invention, the problem of switch-off in conductor-to-conductor antifuses is solved by utilizing conductive electrode materials having a relatively lower thermal conductivity than prior art electrode materials. According to a second aspect of the present invention, the problem of switch-off in conductor-to-conductor antifuses is solved by utilizing relatively thin electrodes, thus increasing their thermal resistance. According to a third aspect of the present invention, a relatively thin barrier layer is placed between one or both of the low thermal conductivity electrodes and the antifuse material in order to prevent reaction between the conductive electrodes and the antifuse material or the materials used in manufacturing such as the etch gas. According to a fourth aspect of the present invention low thermal conductivity conductors are used for both electrodes in the conductor-to-conductor antifuse in order to achieve enhanced reliability and freedom from switch-off. According to a fifth aspect of the present invention switch-off is cured in conductor-to-conductor antifuses without compromising low on-state resistance of the antifuse.

Claims

1. An antifuse disposed on an integrated circuit, said antifuse comprising:

a first conductive electrode having a first thickness and a substantially constant thermal conductivity throughout said first thickness;

a second conductive electrode having a second thickness and a substantially constant thermal conductivity throughout said second thickness;

an insulating antifuse layer located between said first conductive electrode and said second conductive electrode, said insulating antifuse layer comprising materials selected from the group consisting of SiO_x, for 0<

x≦

2, Si₃ N_Y (for 0<

Y≦

4), SiO_X N_Y (for 0<

X≦

2 and 0<

Y≦

4/3) and Amorphous Silicon, said antifuse layer having a thickness much less than either said first thickness or said second thickness, and

a first barrier layer disposed between said first conductive electrode and said insulating antifuse layer,

wherein said first conductive electrode and said second conductive electrode consist substantially of electrically conductive materials with thermal conductivities below 0.4 W cm^-1 K^-1.

2. An antifuse disposed on an integrated circuit, said antifuse comprising:

a first conductive electrode having a first thickness and a substantially constant thermal conductivity throughout said first thickness;

a second conductive electrode having second thickness and a substantially constant thermal conductivity throughout said second thickness;

an insulating antifuse layer located between said first conductive electrode and said second conductive electrode, said insulating antifuse layer comprising materials selected from the group consisting of SiO_x, for 0<

x≦

2, Si₃ N_Y (for 0<

Y≦

4) SiO_X N_Y (for 0<

X≦

2 and 0<

Y≦

4/3) and Amorphous Silicon, said antifuse layer having a thickness much less than either said first thickness or said second thickness, and

a barrier layer disposed between said first conductive electrode and said insulating antifuse layer, said barrier layer comprising materials selected from the group consisting of W, TiW and TiN,

wherein said first conductive electrode and said second conductive electrode consist substantially of electrically conductive materials with thermal conductivities below 0.4 W cm^-1 K^-1.

3. An antifuse disposed on an integrated circuit, said antifuse comprising:

a first conductive electrode consisting substantially of Ti vertically oriented over an insulating film of the integrated circuit, said first electrode having a first thickness and a substantially constant thermal conductivity throughout said first thickness;

a second conductive electrode consisting substantially of Ti vertically oriented over said first electrode, said second electrode having a second thickness and a substantially constant thermal conductivity throughout said second thickness;

an insulating antifuse layer disposed between said first conductive electrode and said second conductive electrode, said insulating antifuse layer comprising SiO_x, for 0<

x≦

2, and having a thickness in the range of about 20 Å

to about 250 Å

, said antifuse layer having a thickness much less than either said first thickness or said second thickness; and

a first barrier layer disposed between said first conductive electrode and said insulating antifuse layer, said barrier layer fabricated from a layer of W of thickness in the range of about 50 Å

-300 Å

.

4. An antifuse according to claim 3 further comprising a second barrier layer disposed between said second conductive electrode and said insulating antifuse layer, said barrier layer fabricated from a layer of W of thickness in the range of about 50 Å

-300 Å

.