A method of fabricating a
metal guard ring (e.g., 139 149 159) around for a
metal fuse 141 and fuse opening 88. The
metal fuse 41 is formed from a second metal layer (M2) (or M3 or M4, etc.) and is connected to an underlying polysilicon layer 22 by fuse interconnections 129A 129B. The method comprises: a) forming a first polysilicon line 22A and a second polysilicon line 22B over at least the fuse area 84 insulated (e.g., 20) from a substrate 10; b) forming one or more levels of fuse interconnects (129A 129B) electrically connected to the first polysilicon line 22A and the second polysilicon line 22B; the fuse interconnects 129A 129B passing through vias in one or more insulating
layers 24 34; c) simultaneously forming a metal fuse 141 connecting the polysilicon interconnects 129A 129B over the fuse area 84 and forming a first
guard ring 139 around a fuse area 84; d) forming an
dielectric layer 144 over the metal fuse 141 and the first
guard ring 139; e) forming a guard ring around the fuse areas 84; the guard ring composed of a plurality of metal wiring
layers 149 159 formed on and through vias in a plurality of
dielectric layers 144 154; and f) forming a fuse opening 88 through at least a portion of the plurality of
dielectric layers 144 154 172 in the fuse area.