In additional embodiments an e-fuse structure depicted in FIG. 5 may be used. The e-fuse may include an Mx level 202 and an Mx+1 level 212. The Mx level 202 may include an Mx dielectric 204 and two Mx metals 206, 208. The Mx+1 level 212 may include an Mx+1 dielectric 214, a tetragonal phase tungsten silicon layer 216, and two vias 220. In such embodiments, the tetragonal phase tungsten silicon layer 216 may be the tetragonal phase tungsten silicon layer formed using the process steps listed above. An Mx+1 cap dielectric 218 may be located above the Mx+1 dielectric 214 and electrically insulate the Mx+1 level 212 from additional interconnect levels (not shown) that may be subsequently formed above. The vias 220 may electrically connect the fuse line 216 to the Mx metals 206, 208. The Mx metals 206, 208, the vias 220, and the tetragonal phase tungsten silicon layer 216 make up the e-fuse.
In either embodiment, a resultant structure is formed in which a low resistivity tetragonal phase tungsten silicon layer forms an electrical connection between two conductive regions. The two conductive regions may be vias, or lines, and may be made of a conductive material such as, for example, copper, tungsten or aluminum. The conductive regions may be electrically isolated from one another using a dielectric material, such that the only path for electric current to move from the first conductive region to the second conductive region is through the tetragonal phase tungsten silicon layer.
