MBIST Pattern Mask Register Reduces Test Time

The patent applies preliminary action by executing all test patterns during the repair mode first to identify failing patterns. The fail status register captures which patterns failed during this initial execution. Then, during the pass-fail mode, only the patterns that failed in the repair mode are re-executed. This preliminary identification of failing patterns allows the system to avoid re-executing patterns that would have passed anyway, thereby reducing total test time while maintaining thorough testing coverage for the problematic patterns.

The patent implements self-service by enabling the MBIST engine to automatically identify and track failing patterns internally using the fail status register, without requiring external tester intervention for data collection and analysis. The pattern mask register automatically updates based on the fail status, and the system autonomously determines which patterns to re-execute in pass-fail mode. This self-service mechanism maintains accurate fail identification while eliminating the need for complex tester involvement in data logging and analysis.

The patent applies universality by designing the fail status register and pattern mask register to serve multiple functions. The fail status register not only tracks which patterns failed but also directly controls the pattern mask register, which in turn determines which patterns are re-executed in pass-fail mode. This multi-functional design allows a single register structure to handle both fail identification and test pattern selection, reducing the need for separate complex control logic while improving test efficiency through targeted re-execution of failing patterns.