Development and Manufacturing Ic Failure Analysis: the Importance of Test and Diagnostics 76 Ieee Design & Test of Computers

failures are unfortunately an inherent part of the microelectronics business, where complexity is growing rapidly. Failures can occur during several points of a product’s life cycle, such as technology or product development and qualification, yield learning, reliability improvement, system manufacture, and field application. The impact of such failures ranges from consequential to catastrophic. While we expect failures during reliability stressing or yield learning on a new technology, mature programs and parts qualified for sale and field application demand competitive quality and reliability levels. Failures during these later phases of production need immediate analysis and corrective action. Whether anticipated or sudden, failures can have a severe business impact. Because narrow market opportunities often drive shortened product cycles, companies need to understand failures and take corrective actions quickly. Electrical characterization, statistical analysis, signature analysis, and process experiments can provide important clues that allow us to infer the cause of failure. But only full root-cause physical failure analysis can provide the incriminating evidence necessary to correct problems with confidence: the picture worth a thousand words. The crucial element of failure analysis is fault localization, a task for which both hardware and software techniques exist (see the adjacent box). Trends toward denser circuits and more sophisticated packaging, however, are limiting physical access to internal chip circuitry and thus diminishing the effectiveness of hardware-based diagnostics. This article reviews hardware and software options for fault localization and shows why software diagnostics must become a key focus within the design, test, and failure analysis communities.