A new version of Technical Report TR18.0-01-25 (TR18) on ESD Electronic Design Automation (EDA) Checks by the ESD Association’s Working Group 18 is about to be released. This article, divided into Part 1 and Part 2, provides guidelines for the EDA industry and the ESD design community for establishing a comprehensive ESD verification flow to address the ESD design challenges of modern ICs. Part 1 covered the concept of ESD checks throughout the IC Design Flow, including Schematic-based and Layout-based ESD checks. Part 2 covers Package-level and System-level checks, ESD Circuit simulation, and ESD TCAD simulation, completing the coverage of all ESD EDA checks described in the Technical Report.
Package-Level ESD Checks
The increasing complexity of IC packaging, especially with advanced process nodes and multi-die (chiplet) System-in-Package (SiP) configurations, necessitates comprehensive ESD verification at the package level. The physical and electrical properties of an IC package significantly influence the ESD protection network’s response. This complexity is further amplified in 2.5D and 3D IC flows, where multiple dies are integrated into a single package, each with unique ESD risks and target levels.
To ensure that the designed protection levels are maintained across all package options, the current state of package-level ESD verification involves several critical steps: extracting metadata of die pads and package pins, setting up EDA tools, defining ESD targets for each signal IO and supply pin, applying appropriate ESD rules on design, and verifying the integrity of the overall ESD protection network considering the additional RLC paths introduced by the package.
Advanced packaging technologies, such as 2.5D and 3D integrations, introduce additional challenges like differentiation between internal (die‑to-die) and external IOs, the huge number of die-to-die IOs to check, integration of chiplets from different process technologies/foundries, use of SI‑interposers and TSVs, and ESD risk associated with the final assembled package and the assembly process itself.
System-Level ESD Checks
System-level checks are an important component of the full spectrum of ESD checks. These checks can be done with SPICE-like simulators via SEED (System Efficient ESD Design), full-wave analysis software, or near-field analysis techniques.
If a failure occurs during a PCB-level ESD qualification, the following analysis methods can be used to diagnose the root cause: perform SEED analysis of the PCB path containing the failed IC component, perform scanning analysis by applying near-field electromagnetic interference pulses to failing areas of the PCB topology, or execute a full wave analysis on the failing PCB to identify the failing topology.
ESD Circuit Simulation (SPICE)
Circuit simulation is invaluable for the design of ESD protection networks, prediction of ESD robustness, and debugging of ESD failures. Circuit simulation requires proper configuration of the ESD source, ESD protection device, and ESD path as the simulation test bench.
An HBM ESD source is typically modeled as an equivalent lumped circuit to produce the exponentially decaying current pulse (Figure 1a). A CDM ESD source can be similarly represented, or by an array of capacitors attached to the IC in a distributed manner to model the field coupling from the CDM tester (Figure 1b). A behavioral approach is also applicable, such as using a damped sinusoidal wave to simulate CDM current pulse.
Figure 1b: CDM ESD simulation test-bench
An ESD event is most comprehensively simulated through whole-chip transient simulation with nonlinear ESD device models. However, such simulation is traditionally resource-intensive and time‑consuming. Simplifications can be made to improve simulation efficiency, with trade-offs in accuracy.
ESD TCAD Simulation
Technology Computer-Aided Design (TCAD) represents a holistic approach that comprehends physical device structure, fabrication process simulation, and semiconductor physics models. TCAD can predict parameters of ESD devices, simulate device behavior within ESD protection circuits, and develop rules for automatic design checkers.
TCAD applications are effective at the technology and ESD IP development stages. One of the most important representations of a TCAD approach for EDA is mixed-mode simulation, which extends transient simulations’ capabilities from a single device structure to several devices within small circuits (Figure 2).
Conclusions
ESD EDA verification is a complex task. IC companies use different ESD protection approaches, design flows, and verification tools. The Technical Report introduces several generic rules that can be used as the basis for a typical ESD EDA verification flow. As more ESD EDA tools become more mature and commercially available, there will be further opportunities for standardizing ESD EDA verification approaches and specific ESD checks.
