, Intel Corporation
Pages: pp. 56-57
Each year, for the past 29 years, industry and academic professionals have gathered at the International Test Conference to push forward the state of the art of test. ITC 97 was the biggest conference yet, and the Microprocessor Test sessions offered some of the broadest and most detailed papers ever presented.
In some ways, microprocessor test is a reflection or a superset of today's industrial test issues. Microprocessors challenge us in many ways.
This special section of IEEE Design and Test features articles based on several of the papers presented at the ITC 97 Microprocessor Test sessions. The authors discuss dramatically different methods to achieve high logic and memory test coverage, and each solves one or more microprocessor test problems. We can use the ideas as a basis for testing other devices. Each of the products described is in production with proven quality and manufacturing volume. They demonstrate the practical application of different test techniques.
For instance, each article covers the challenge of testing large embedded caches—which is the major consumer of transistors in all the microprocessors referenced. The methods to achieve the test goals vary widely, but each one acknowledges the need for good memory test. Of special interest is the HP PA8500 article, which focuses on embedded memory test and the algorithms used.
The Alpha, K6, ColdFire, and Pentium Pro authors discuss methods for speed testing, both for binning and delay defects. Pay close attention to the widely different methods of speed test: at-speed functional patterns, at-speed scan, and scan-based delay faults.
Authors also reference I DDQ as a key technology.
Every article covers DFT features for logic, caches, or both. While the methods used differ greatly, all of them achieve the desired final results. S390 is an example of a very rigorous approach to DFT.
Finally, the PowerPC 750 article addresses test program generation and grading.
The authors of these articles have graciously detailed their works with the idea that we will all benefit from their experiences. I thank them all for the high-quality technical material presented here.
Readers interested in microprocessor test can find valuable information in the Proceedings of the IEEE International Test Conference and the Proceedings of the IEEE VLSI Test Symposium; copies are available from the IEEE Computer Society Press in Los Alamitos, California, at http://computer.org.
Many CAD vendors hold classes in the effective use of their tools and will supply details of their BIST and logic DFT tools. Failure mechanisms and defect study examples are included in many of the root-cause papers presented at ITC, which meets each year in the fall.