Influence of the STI on Single-Event Transients in Bulk FinFETs

The single-event transient (SET) produced by laser irradiation in a bulk FinFET is found to have a large plateau current in the tail. Three-dimensional technology computer-aided design (TCAD) simulation results show that the cause of the plateau current is the shallow trench isolation (STI) on both sides of the channel stop of a bulk FinFET. When the bulk FinFET is irradiated by heavy ions or laser, the electron-hole pairs are generated by ionization in the active region and the STI of the device. The electron mobility in the STI is much greater than that of the hole, so the electrons generated in the STI are collected quickly, and the holes are left in the STI. The holes left in the STI generate an electric field and form an electron inversion layer in the channel stop. Under the bias voltage of the drain terminal, the electrons in the source flow to the drain through the electron inversion layer in the channel stop to form a drain current. Since holes can exist in the STI for more than 100 ns, the drain current caused by the electron inversion layer forms a plateau current at the tail of the pulse. And the plateau current increases as the gate length of the bulk FinFET becomes shorter, and decreases as the fin width of the bulk FinFET becomes larger.