Integrated modeling of Self-heating of confined geometry (FinFET, NWFET, and NSHFET) transistors and its implications for the reliability of sub-20 nm modern integrated circuits.

The evolution of transistor topology from planar to confined geometry transistors (i.e., FinFET, Nanowire FET, Nanosheet FET) has met the desired performance specification of sub-20nm integrated circuits (ICs), but only at the expense of increased power density and thermal resistance. Thus, self-heating effect (SHE) has become a critical issue for performance/reliability of ICs. Indeed, temperature is one of the most important factors determining ICs reliability, such as Negative Bias Temperature Instability (NBTI), Hot Carrier Injection (HCI), and Electromigration (EM). Therefore, an accurate SHE model is essential for predictive, reliability-aware ICs design. Although SHE is collectively determined by the thermal resistances/capacitances associated with various layers of an IC, most researchers focus on isolated components within the hierarchy (i.e., a single transistor, few specific circuit configurations, or specialized package type). This fragmented approach makes it difficult to verify the implications of SHE on performance and reliability of ICs based on confined geometry transistors. In this paper, we combine theoretical modeling and systematic transistor characterization to extract thermal parameters at the transistor level to demonstrate the importance of multi-time constant thermal circuits to predict the spatio-temporal SHE in modern sub-20nm transistors. Based on the refined Berkeley Short-channel IGFET Model Common Multi-Gate (BSIM-CMG) model, we examine SHE in typical digital circuits (e.g., ring oscillator) and analog circuits (e.g., two-stage operational amplifier) by Verilog-A based HSPICE simulation. Similarly, we develop a physics-based thermal compact model for packaged ICs using an effective media approximation for the Back End Of Line (BEOL) interconnects and ICs packaging. We integrate these components to investigate SHE behavior implication on ICs reliability and explain why one must adopt various (biomimetic) strategies to improve the lifetime of self-heated ICs.