Programming mechanism of polysilicon fuse links

We have studied the programming mechanism of polysilicon fuse links using both electrical measurements and microstructure studies with the scanning electron microscope. We find that a gap forms only after a transition to a second breakdown- like state. In this state the current flows mainly through a molten filament. The applied electric field causes drift of positive silicon ions in the filament, forming a gap near the positive contact. A simple electrothermal model is described which gives a good fit to the measured I-V characteristics.