Self-Heating and Radiation Hardness Studies of 3nm GAA-FET-Based SRAM with Different Substrate Isolation Techniques

Abstract

In this work, 3D full-domain 3 nm gate-all-around field-effect transistor (GAA-FET) static random access memories (SRAMs) with various substrate isolation techniques are simulated using Technology Computer-Aided Design (TCAD). In addition to the traditional bottom dielectric isolation (BDI), which isolates the source/drain (S/D) from the substrate (dubbed SDBDI), and the punch-through stopper (PTS), a novel channel-BDI (C-BDI) is proposed, allowing S/D-to-substrate connection. The self-heating effect and radiation hardness due to various isolation techniques are studied. It is found that, firstly, the increase in self-heating due to BDI is negligible. Secondly, in the novel CBDI, even without PTS, the increase in leakage current IOFF is minimal. Thirdly, for SD-BDI with underlap (to minimize stress relaxation), while IOFF increases, the static noise margin (SNM) remains unchanged and robust against single-event upset (SEU) even if the underlap is as much as 20 nm. Finally, all structures are immune to the alpha-particle SEU, and BDI enhances the radiation hardness substantially. Moreover, radiation hardness is insensitive to BDI thickness.