Built-in current testing
P. Nigh · 1990
The cost and complexity of testing are two of the major bottlenecks in developing new VLSI products. In addition, it has become more difficult to ensure high quality levels of IC products due to inadequate test coverage of the defects which actually occur in the manufacturing process. Therefore, new testing methods must be developed which are both cost-effective and are able to detect a higher percentage of manufacturing defects. We have developed a new testing method, called Built-In Current (BIC) testing, aimed at improving the quality and efficiency of testing. This testing method detects defects in CMOS ICs by applying on-chip sensors that monitor the power supply bus for abnormalities in quiescent current. It has been found through simulation and fabrication experiments that a high percentage of realistic defects can be detected by this method, including many types of defects which are not detected by stuck-fault testing. During the fabrication experiments, we tested a die having up to 1800 transistors with a single BIC sensor (area overhead $<$0.1%). A unique aspect of BIC testing is that it can be applied at all levels of assembly, including during normal system operation. We have also developed and implemented a unique test generation methodology for BIC testing. Test vectors are generated using realistic faults models and actual IC layouts which leads to a higher quality of vectors than traditional methods.