Radiation effects on multi-channel Forksheet-FET and Nanosheet-FET considering the bottom dielectric isolation scheme

Abstract

This study analyzes the single-event transient (SET) characteristics of alpha particles on multi-channel Forksheet-FET and Nanosheet-FET at the device and circuit levels through 3D TCAD simulations. The study investigates the differences in SET responses based on the energy and incident position of incoming alpha particles, considering the structural variances between Forksheet-FET and Nanosheet-FET, as well as the presence or absence of bottom dielectric isolation (BDI) in the fabrication process. Specifically, the introduction of BDI is observed to significantly suppress the voltage drop caused by ‘unintended' current, as it can block the substantial electron-hole pairs (EHP) generated by injected alpha particles in the bulk substrate from reaching the FET terminals. Furthermore, it was confirmed that the size of abnormal current decreases as the energy of the injected alpha particle increases. Additionally, evaluating the response to SET based on the fundamental logic circuit, the CMOS inverter, revealed relatively small abnormal voltage drops for both Forksheet and Nanosheet when BDI was applied, confirming high immunity to radiation effects. Moreover, it can be observed that the application of BDI enhances reliability from a memory perspective by effectively suppressing voltage flips in the SRAM's cross-coupled latch circuit.