Reprogrammable metal-to-metal antifuse employing carbon-containing antifuse material

• US 7,393,722 B1
• Filed: 08/01/2005
• Issued: 07/01/2008
• Est. Priority Date: 10/02/2001
• Status: Expired due to Fees

• Current Assignee: Microsemi SoC Corp.
• Original Assignee: Actel Corporation (Microchip Technology Incorporated)
• Inventors: Issaq, A. Farid, Hawley, Frank, McCollum, John
• Primary Examiner(s): Nadav, Ori
• Application Number:
  US11/195,002
• Time in Patent Office: 1,065 Days
• Field of Search: 438/105, 438/131, 438/467, 438/600, 438/627, 438/637, 438/643, 438/653, 438/675, 438/700, 438/931, 438/957
• US Class Current: 438/131
• CPC Class Codes: G11C 17/16 using electrically-fusible links
• 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
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

A reprogrammable metal-to-metal antifuse is disposed between two metal interconnect layers in an integrated circuit. A lower barrier layer is formed from Ti. A lower adhesion-promoting layer is disposed over the lower Ti barrier layer. An antifuse material layer selected from a group comprising at least one of amorphous carbon and amorphous carbon doped with at least one of hydrogen and fluorine is disposed over the lower adhesion-promoting layer. An upper adhesion-promoting layer is disposed over the antifuse material layer. An upper Ti barrier layer is disposed over the upper adhesion-promoting layer.

Claims

1. A method for fabricating a reprogrammable metal-to-metal antifuse, comprising:

planarizing an insulating layer and a tungsten plug;

forming a lower Ti barrier layer over said insulating layer and said tungsten plug;

forming a lower adhesion-promoting layer over said lower Ti barrier layer, said lower adhesion-promoting layer selected from the group comprising Si_xC_y and Si_xN_y;

forming an antifuse material layer over said lower adhesion-promoting layer, wherein said antifuse material layer is selected from the group comprising amorphous carbon, amorphous carbon doped with at least one of hydrogen and fluorine, and amorphous silicon carbide;

forming an upper adhesion-promoting layer over said antifuse material layer, said upper adhesion-promoting layer selected from the group comprising Si_xC_y and Si_xN_y;

forming an upper Ti barrier metal layer over said antifuse material layer;

forming an oxide or tungsten hardmask layer over said barrier metal layer;

forming a layer of photoresist over said hardmask layer;

defining said hardmask layer;

removing said photoresist;

defining a shape of a stack for said antifuse by etching said upper Ti barrier layer, said upper adhesion-promoting layer, said antifuse material layer, said lower adhesion-promoting layer, and said lower Ti barrier metal layer using said hardmask layer as a mask;

forming an insulating layer over said stack;

forming an aperture in said insulating layer;

forming a metal interconnect layer over said insulating layer and in said aperture;

forming a second masking layer over said metal interconnect layer; and

defining said metal interconnect layer.

2. The method of claim 1, wherein said forming said antifuse material layer comprises forming said antifuse material layer to a thickness of from about 10 nm to about 80 nm.

3. The method of claim 1, wherein said forming said Ti barrier metal layer comprises forming said Ti barrier metal layer to a thickness of from about 25 nm to about 200 nm.

4. The method of claim 1, wherein said lower and upper adhesion-promoting layers are essentially monolayers.

5. The method of claim 1, wherein said forming an antifuse material layer comprises depositing said antifuse layer from an acetylene source gas.