Breakdown of gate oxides during irradiation with heavy ions

Breakdown of thin gate oxides from heavy ions is investigated using capacit or test structures. Soft breakdown was observed for 45 Angstrom oxides, but not for 75 Angstrom oxides. Lower critical fields were observed when exper iments were done with high fluences during each successive step. This impli es that oxide defects play an important role in breakdown from heavy ions a nd that breakdown occurs more readily when an ion strike occurs close to a defect site. Critical fields for 75 Angstrom oxides are low enough to allow gate rupture to occur at normal supply voltages for ions with high LET.