Transistor Self-Heating: The Rising Challenge for Semiconductor Testing

Quantum confinement in 3-D device structure together with the newly employed materials like silicon-germanium (SiGe) in advanced technologies (e.g., FinFET, nanowire, nanosheets, etc.) makes transistors seriously suffer from localized self-heating effects in which generated heat within the transistor's channel is trapped inside. This is mainly due to the much lower channel and surrounding material thermal conductivity and hence lower ability for heat dissipation along with the firm isolation needed for better gate control. Self-heating effects strongly accelerate transistor aging and all the underlying defect generation mechanisms leading to serious reliability problems during the early life of chips. The key challenge in transistor self-heating when it comes to semiconductor testing is the profound difficulty in measuring self-heating directly as generated heat is trapped inside the transistor. Failing in capturing self-heating phenomenon during IC testing would later lead to chips malfunctions at run-time and hence early life failures because of reliability degradations and failure mechanisms will be unexpectedly accelerated akin to excessive internal temperatures. In this paper, we investigate the impact of self-heating effects on n-type and p-type FinFET transistors calibrated with Intel 14 nm measurement data using mature Technology CAD (TCAD) simulations. Then, the industry standard compact model for FinFET technologies (BSIM-CMG) is carefully calibrated to accurately model and reproduce all measurements. This enables circuit's designers, for the first time, to accurately investigate how emerging self-heating effects in transistors impacts the performance and power of large circuits. This opens new doors for developing novel Design-for-Testing methods that effectively reveal self-heating effects and increase the yield of chips.