White Paper 4Understanding Electrical Overstress - EOS-1

Abstract Damage signatures from Electrical Overstress (EOS) are the leading reported cause of returns in integrated circuits and systems that have failed during operation. Solutions to this problem are hindered by a prevailing misconception in the electronics industry that insufficient robustness to electrostatic discharge (ESD) is a primary cause of EOS. This document, White Paper 4, (WP) has been carefully compiled by the Industry Council on ESD Target Levels to foster a unified global understanding of what constitutes EOS and how EOS damage signatures can result from a wide variety of root causes. The paper begins by outlining a brief history of EOS. It then presents the results of an industry-wide EOS survey. This survey gathered information on the types of EOS problems experienced by over 80 different companies, the relative importance of EOS to their overall business, and the methods assigned by these companies to address EOS issues. The survey provides a combined picture from which a more comprehensive definition of EOS can be made. The numerous categories and sub-categories of EOS root causes are explored in an attempt to understand how to create better specifications which will reduce their occurrence. In addition to the survey results, this paper studies many field returns with EOS damage signatures to establish the underlying root causes of damage and offers the respective identified solutions. The survey and the case studies both show that successful failure analysis (FA) depends on careful communication between customer and supplier from the time a failure occurs until its cause has been discovered. Detailed investigation into manufacturing and handling processes is often necessary to accurately identify the root cause. This paper outlines a basic summery of the typical process flow for component electrical failure analysis. The key point is that EOS issues can be mitigated when the proper understanding of IC design, factory and field environments, and system implementation is combined with effective communication across all these areas.