Fusing Mechanism of Nichrome Thin Films

(1) Conduction electrons in nichrome have a short mean-free path. This maximizes E2R heating and precludes electromigration in the direction of electron flow as a fusing mechanism. (2) Transmission electron microscopy is the only effective analytical tool to characterize the programmed fuse gap structure. (3) Nichrome fuses program by molten metal (nickel, chrome) ions moving in the presence of an electric field. The final structure resembles a frozen splash and is described by fluid dynamics. (4) Thermal analysis coupled with empirical programmed fuse data indicate a threshold power density for fusing. If this power density is exceeded, which can be assured if the programming time utilized is as specified, the fuse gap will be wide and reliable. If this power density threshold is only matched, it is possible to create a marginal fuse. (5) Life test results indicate programmed PROM reliability is equivalent to devices of the same complexity that do not utilize fusible links.