The magnitude of the current exceeding the threshold current density initiates electromigration of {HEAD ~ the source/drain silicide} into the channel region, such that the source/drain of the FET is shorted to {TAIL ~ the substrate} after programming 
The magnitude of the current exceeding the threshold current density initiates electromigration of { HEAD ~ the source / drain silicide } into the channel region , such that the source / drain of the FET is shorted to { TAIL ~ the substrate } after programming
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH