Deep insights into dielectric breakdown in tunnel FETs with awareness of reliability and performance co-optimization

The gate dielectrics reliability in Tunnel FETs (TFETs) has been thoroughly investigated for the first time, which is found to be the dominant device failure mechanism compared with bias temperature ins tability degradation, and is much worse than MOSFETs with the same gate stacks due to a new stronger localized dielectric field peak at gate/source overlap region. The non-uniform electric field of dielectric in TFET also leads to the different mechanisms between soft breakdown and hard breakdown failure. Moreover, dielectric-field-associated parameters are discussed in detail, showing an intrinsic trade-off between dielectrics reliability and device performance optimization caused by the positive correlation between dielectric field and source junction field. A new robust design consideration is further proposed for reliability and performance co-optimization, which is experimentally realized by a new TFET design with both dramatically improved performance and reliability, indicating its great potentials for ultralow-power applications.