Defect-oriented testing methods have come a long way from a mere interesting academic exercise to a hard industrial reality. Many factors have contributed to its industrial acceptance. Traditional approaches of testing modern integrated circuits have been found to be inadequate in terms of quality and economics of test. In a globally competitive semiconductor market place, overall product quality and economics have become very important objectives. In addition, electronic systems are becoming increasingly complex and demand components of the highest possible quality. Testing in general and defect-oriented testing in particular help in realizing these objectives. For contemporary System on Chip (SoC) VLSI circuits, testing is an activity associated with every level of integration. However, special emphasis is placed for wafer-level test, and final test. Wafer-level test consists primarily of dc or slow-speed tests with current/voltage checks per pin under most operating conditions and with test limits properly adjusted. Basic digital tests are applied and in some cases low-frequency tests to ensure analog/RF functionality are exercised as well. Final test consists of checking device functionality by exercising RF tests and by applying a comprehensive suite of digital test methods such as I , delay fault testing, DDQ stuck-at testing, low-voltage testing, etc. This partitioning choice is actually application dependent.
Failures of nano-metric technologies owing to defects and shrinking process tolerances give rise to significant challenges for IC testing. As the variation of fundamental parameters such as channel length, threshold voltage, thin oxide thickness and interconnect dimensions goes well beyond acceptable limits, new test methodologies and a deeper insight into the physics of defect-fault mappings are needed. In Defect-Oriented Testing for Nano-Metric CMOS VLSI Circuits state of the art of defect-oriented testing is presented from both a theoretical approach as well as from a practical point of view. Step-by-step handling of defect modeling, defect-oriented testing, yield modeling and its usage in common economics practices enables deeper understanding of concepts.
The progression developed in this book is essential to understand new test methodologies, algorithms and industrial practices. Without the insight into the physics of nano-metric technologies, it would be hardto develop system-level test strategies that yield a high IC fault coverage. Obviously, the work on defect-oriented testing presented in the book is not final, and it is an evolving field with interesting challenges imposed by the ever-changing nature of nano-metric technologies. Test and design practitioners from academia and industry will find that Defect-Oriented Testing for Nano-Metric CMOS VLSI Circuits lays the foundations for further pioneering work.
