Anti-fuse structure for reducing contamination of the anti-fuse material

Abstract

An anti-fuse structure formed in accordance with the present invention includes a conductive layer base. A layer of anti-fuse material overlies the conductive base layer. On top of the anti-fuse layer is an insulating layer, in which a via hole is formed to the anti-fuse layer. The lateral dimension of the via hole is less than about 0.8 microns. Provided in the via hole is a conductive non-Al plug including a conductive barrier material such as TiN or TiW to contact the anti-fuse material and overlie the insulating layer. Tungsten is effectively used as the non-Al plug. An electrically conductive layer is formed over the plug and is separaged from the anti-fuse layer by at least one-half the depth of the via hole. The structure is then programmable by application of a programming voltage and readable by application of a sensing voltage, which is lower than the programming voltage.

What is claimed is: 
     
       1. An anti-fuse structure comprising: a conductive base layer;   a layer of anti-fuse material formed over said conductive base layer;   an insulating layer formed over said anti-fuse layer, said insulating layer being provided with a via hole to said anti-fuse layer, and said via hole .Iadd.having sides and .Iaddend.having a lateral dimension no greater than about 0.8 microns and having a depth;   .Iadd.a conductive barrier layer consisting of a barrier material selected from the group consisting of TiW, TiN, and chromium said conductive barrier layer having a first portion overlying said anti-fuse material a second portion extending upward along said sides of said via hole and a third portion overlying a portion of said insulating layer; .Iaddend.   a conductive non-Al plug .[.including a.]. .Iadd.above said first portion of said .Iaddend.conductive barrier .[.material chosen from the group consisting essentially of TiW, TiN, and chromium, provided within said via hole and in contact with said anti-fuse layer.]. .Iadd.layer .Iaddend.such that said anti-fuse structure may be programmed by providing a programming voltage between said conductive base layer and said conductive barrier .[.material.]. .Iadd.layer.Iaddend., and may be read by providing a sensing voltage, which is lower than said programming voltage, between said conductive base layer and said conductive barrier material; and   an electrically conductive layer formed over and in electrical contact with said plug, said electrically conductive layer being separated from the anti-fuse layer by said plug by at least one-half said depth of the via hole.   
     
     
       2. An anti-fuse structure as recited in claim 1 wherein said lateral dimension of said via hole is no greater than about 0.6 microns. 
     
     
       3. An anti-fuse structure as recited in claim 1 wherein said conductive barrier .[.material.]. .Iadd.layer .Iaddend.is conformably applied within said via hole, and wherein said non-Al plug further comprises a W plug within said via hole and in contact with said conductive barrier .[.material.]. .Iadd.layer.Iaddend.. 
     
     
       4. An anti-fuse structure as recited in claim 3 wherein said electrically conductive layer includes a conductive line comprising aluminum over said conductive barrier .[.material.]. .Iadd.layer .Iaddend.and in contact with said W plug. 
     
     
       5. An anti-fuse structure as recited in claim 3 wherein said electrically conductive layer and said W plug are integrally formed as parts of a blanket layer of tungsten over said conductive barrier .[.material.]. .Iadd.layer .Iaddend.and within said via hole. 
     
     
       6. An anti-fuse structure as recited in claim 5 wherein said tungsten blanket layer is patterned to provide a tungsten interconnect contacting said plug. 
     
     
       7. An anti-fuse structure as recited in claim 3 wherein said electrically conductive layer comprises a conductive line comprising aluminum over said insulating layer and in contact with said W plug. 
     
     
       8. An anti-fuse structure as recited in claim 1 wherein said .Iadd.conductive .Iaddend.barrier .[.material.]. .Iadd.layer .Iaddend.comprises TiN which substantially completely fills said via hole as said non-Al plug. 
     
     
       9. An anti-fuse structure as recited in claim 1 wherein said conductive base layer has a thickness in the range of about 1000-10,000 Å. 
     
     
       10. An anti-fuse structure as recited in claim 9 wherein said conductive base layer has a thickness of about 2200 Å. 
     
     
       11. An anti-fuse structure as recited in claim 1 wherein said anti-fuse material has a thickness in the range of about 500-5,000 Å. 
     
     
       12. An anti-fuse structure as recited in claim 11 wherein said anti-fuse material has a thickness of about 1200 Å. 
     
     
       13. An anti-fuse structure as recited in claim 1 wherein said insulating layer has a thickness in the range of about 1000-10,000 Å. 
     
     
       14. An anti-fuse structure as recited in claim 13 wherein said insulating layer has a thickness of about 3000 Å. 
     
     
       15. An anti-fuse structure as recited in claim 1 wherein said conductive barrier .[.material.]. .Iadd.layer .Iaddend.has a thickness in the range of about 500-3000 Å. 
     
     
       16. An anti-fuse structure as recited in claim 15 wherein said conductive barrier .[.material.]. .Iadd.layer .Iaddend.has a thickness of about 1000 Å. 
     
     
       17. An anti-fuse structure as recited in claim 3 wherein said W plug has a height of at least 1/2 of said depth of said via hole. 
     
     
       18. An anti-fuse structure as recited in claim 5 wherein said blanket layer of tungsten has a thickness of about 0.8 times the lateral dimension of the via hole. 
     
     
       19. An anti-fuse structure as recited in claim 8 wherein said .Iadd.conductive .Iaddend.barrier .[.material.]. .Iadd.layer .Iaddend.has a thickness of about 0.8 times the lateral dimension of the via hole. 
     
     
       20. An anti-fuse structure as recited in claim 6 further comprising an aluminum interconnect provided over said tungsten interconnect. 
     
     
       21. An anti-fuse structure as recited in claim 5 wherein the plug substantially fills the via hole and wherein an aluminum layer is deposited over the blanket layer such that the aluminum layer is separated from the anti-fuse layer by at least about the depth of the via hole. 
     
     
       22. An anti-fuse structure as recited in claim 21 wherein the electrically conductive layer has a thickness and wherein said distance separating the aluminum layer from the anti-fuse layer is equal to at least the height of the plug plus said thickness of the electrically conductive layer.