Characterization of microdose damage caused by single heavy ion observed in trench type power MOSFETs

Ikeda, Naomi*; Kuboyama, Satoshi*; Maru, Akifumi*; Hirao, Toshio; Abe, Hiroshi; Tamura, Takashi*

The trench structure showed an anomalously large degradation by heavy ion irradiation. For the trench structure, ions irradiated normal to the chip surface traverse the gate oxide along the entire length of the channel. Therefore, there is a possibility that the trapped holes resulting from the ion traverse introduce the anomalously large leakage current path. This phenomenon is apparently attributable to the microdose effect. In the previous report, the microdose effect was identified on both trench and planner type of power MOSFETs by real-time measurement of the threshold voltage shift during the heavy ion irradiation with very long range. In this study, detailed characterization of the microdose effects was carried out with several in species. As a result, several damage parameters introduced in the gate oxide by a single ion, such as physical damage size and trapped hole density in the damage region were estimated.