Effects of Programming Variations on Nichrome Link PROMS

Devices from two separate PROM manufacturers utilizing nichrome technology were subjected to variations in programming pulses to determine effects on the fusible links. After programming, devices were chemically etched and a Scanning Electron Microscope (SEM) analysis was conducted on the selectively programmed fuses. A rectangular pulse corresponding to the vendors programming specification was used to program the fuses. However, during programming the pulse amplitude was adjusted to simulate the effect of variations in energy levels delivered by the on-chip addressing circuitry to the fusible links. The amplitudes were adjusted to extend the time required for fusing to a range of 100 ¿s to several seconds. Under SEM examination, the appearance of the fused gaps could be correlated to the fusing time during programming. A description of experiments performed, along with SEM photographs-are presented.