Cross-coupled Self-Heating and Consequent Reliability Issues in GaN-Si Hetero-integration: Thermal Keep-Out-Zone Quantified

Three-dimensional (3D) hetero-integration (HI) allows Moore's law to be extended by integrating multiple materials and device technologies onto a single platform, thereby increasing the device density, performance, and functionality. 3D- HI unlocks new circuit applications and capabilities, for instance, by combining III- V devices with high-density and low-cost silicon digital control circuits. However, typically the design processes of such HI systems focus on process or performance considerations without accounting for cross-coupled reliability. We assert that the 3D-HI design would be suboptimal unless we explicitly account for the reliability issues emerging from, for example, the cross-coupled self-heating effects (SHE) that can pose severe reliability challenges of such hetero-integrated circuits. As such, we (i) propose a thermal model to predict the maximum temperature (T_max) attained by Si devices that are heterogeneously integrated with a hot GaN power transistor, (ii) derive an analytical model to define thermal keep-out-zone (T-KOZ) between different devices, and (iii) demonstrate how reliability issues in Si transistor, such as negative bias temperature instability (NBTI), hot carrier injection (HCI) and interconnect electromigration (EM) can be mitigated by carefully selecting the substrate material and implementing forced cooling. The method is generic and can be tailored for any arbitrary combination of technologies.