Programmable electronic fuse

Abstract

A programmable device (eFuse), includes: a substrate ( 10 ); an insulator ( 13 ) on the substrate; an elongated semiconductor material ( 12 ) on the insulator, the elongated semiconductor material having a first end ( 12 a ), a second end ( 12 b ), a fuse link ( 11 ) between the ends, and an upper surface S. The semiconductor material includes a dopant having a concentration of at least 10*17/cc. The first end ( 12 a ) is wider than the second end ( 12 b ), and a metallic material is disposed on the upper surface. The metallic material is physically migratable along the upper surface responsive to an electrical current I flowable through the semiconductor material and through the metallic material.

1 . A programmable device, comprising:
 a substrate;   an insulator on said substrate;   an elongated semiconductor material on said insulator, said elongated semiconductor material having a first end, a second end, a fuse link between the ends, and an upper surface.   wherein said semiconductor material includes a dopant having a concentration of at least 10*17/cc,   said first end is wider than said second end, and   a metallic material is disposed on said upper surface, said metallic material being physically migratable along said upper surface responsive to an electrical current I flowable through said semiconductor material and through said metallic material.   
   
   
       2 . The programmable device of  claim 1 , wherein the dopant is “n” or “p” type and the semiconductor material is doped in the range of approximately 10*17/cc to approximately 10*21/cc. 
   
   
       3 . A programmable device of  claim 1 , further comprising an insulating layer overlying the silicide layer, the insulating layer being non-reactive with the metallic layer during a programming of the device. 
   
   
       4 . The programmable device as claimed in  claim 1 , further comprising an energy source connected to said elongated semiconductor material, for causing an electrical current to flow through said elongated semiconductor material and through said metallic material for a predetermined time, and for causing said metallic material to migrate along said upper surface. 
   
   
       5 . The programmable device as claimed in  claim 1 , wherein said elongated semiconductor material is selected to have a thickness of about 120 nm 
   
   
       6 . The programmable device as claimed in  claim 1 , where said semiconductor material is selected to have a substantially uniform thickness in the range of approximately 60 nm to approximately 250 nm 
   
   
       7 . The programmable device as claimed in  claim 1 , wherein said fuse link has a length greater than five times the fuse link width. 
   
   
       8 . The programmable device of  claim 1 , wherein said fuse link has a length that is less than 15 times the fuse link width. 
   
   
       9 . The programmable device as claimed in  claim 1 , wherein said metallic material is a metallic silicide selected from the group consisting of Nickel silicide and Cobalt silicide. 
   
   
       10 . The programmable device of  claim 1 , wherein the elongated semiconductor material is a polysilicon and the metallic material is a metallic alloy, and the ratio of resistivities of the polysilicon and metallic alloy ranges between 20 to 50, and preferably 30. 
   
   
       11 . The programmable device of  claim 1 , wherein a thickness ratio of the semiconductor material and metallic material ranges between 3 to 8, and preferably about 6. 
   
   
       12 . The programmable device of  claim 1 , wherein a non-reactive insulating layer of SiN is disposed above the metallic material. 
   
   
       13 . The programmable device of  claim 12 , wherein the SiN has a thickness greater than 3000 angstroms. 
   
   
       14 . The programmable device of  claim 1 , wherein the insulator has a substantially uniform thickness of approximately 3000 angstroms. 
   
   
       15 . A programmable device for reliably achieving a post-programming resistance greater than 5 Kohms, said programmable device comprising:
 a substrate;   an insulator on said substrate;   an elongated semiconductor material having a constant first thickness and disposed on said insulator, said elongated semiconductor material having a first end, a second end, a fuse link between the ends, and an upper surface;   a metallic material having a constant second thickness and disposed on said upper surface; and   at least one programming transistor configured to supply an electrical current, I, having a magnitude between a first value and a second value through said elongated semiconductor material and through said metallic material;   wherein said semiconductor material includes a dopant of one conductivity type at a concentration of at least 10 17  dopants/cc, while not including any dopant of an opposite conductivity type; said first end is wider than said second end, and said metallic material being physically migratable along said upper surface responsive to said electrical current; wherein said first value is set between a first range of current level that causes a post-program resistance distribution that is wide and on a low side of approximately 5 Kohms and a second range of current level that causes said post-program resistance to be greater than 5 Kohms and tightly distributed without any rupture in said elongated semiconductor material; and wherein said second value is set between said second range of current level and a third range of current level that ruptures said elongated semiconductor material and said post-program resistance shows a two mode distribution.