The electron irradiation effects on silicon gate dioxide used for power MOS devices

The work provides experimental results of high energy electron irradiation effects on silicon dioxide used for power MOS devices. A systematic increase of the threshold voltage has been observed in irradiated IGBT and VDMOS devices processed on Si < 100 > and Si < 111 >, respectively. The threshold voltage shift has been interpreted as a result of the accumulated charge in the gate oxide. Single event gate rupture has been observed and attributed to the recoil ion interaction with the gate SiO2. The result has been corroborated by reliability stress tests. After electron irradiation, an increase in breakdown voltage appeared on all devices which was attributed to a change in the surface impact ionisation coefficient. The change is most notable in devices processed on Si substrate with < 111 > orientation. (C) 2001 Elsevier Science Ltd. All rights reserved.