LBIST Root Cause Identification via Iterative Macro Isolation
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Solution Overview
Problem
Current logic-built-in-self-test (LBIST) procedures face challenges in identifying the root cause of intermittent failures in integrated circuits, as these failure mechanisms can be difficult to pinpoint using existing diagnostic techniques.
Innovation Solution
A method and system for root cause identification in integrated circuits using LBIST, which involves channel scan paths, macros associated with each scan path, and a processor to initiate and analyze test cycles, identify failing cycles and channels, and iteratively check macros to determine the root cause of failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LBIST procedures are used to test integrated circuits, then test coverage is achieved, but root cause identification for intermittent failures becomes difficult
Solution Approach 1:
The patent segments the testing process into multiple phases: initial LBIST test execution, failure detection, diagnostic mode activation, and iterative macro isolation. By dividing the complex diagnostic task into manageable segments, the system can systematically narrow down the root cause without being overwhelmed by the complexity of intermittent failures
Solution Approach 2:
The patent implements preliminary actions by pre-configuring diagnostic infrastructure including multiple scan paths, signature registers, and diagnostic controllers before testing begins. The system also performs preliminary macro identification and creates test benches in advance, enabling rapid root cause analysis when failures occur without requiring complex post-failure setup
2Measurement precision
If iterative macro checking is performed to identify root cause, then diagnostic precision improves, but test time increases
Solution Approach 1:
The patent segments macros into groups associated with different scan paths and uses iterative enabling/disabling of macro groups to quickly eliminate non-faulty segments. This segmented approach reduces the number of iterations needed compared to checking each macro individually, thereby reducing diagnostic time while maintaining precision
Solution Approach 2:
The patent applies partial action by enabling only one macro or a small group of macros at a time during diagnostic iterations rather than testing all macros simultaneously. This selective partial testing reduces the overall test time required while still achieving precise root cause identification through systematic elimination
3Measurement precision
If multiple scan paths are used to improve diagnostic capability, then root cause identification capability improves, but system complexity increases
Solution Approach 1:
The patent designs scan paths and signature registers that serve multiple functions: they are used both for normal LBIST operation and for detailed diagnostic mode analysis. The same infrastructure supports both macro testing and iterative macro isolation, eliminating the need for separate dedicated diagnostic hardware and reducing overall system complexity
Solution Approach 2:
The patent introduces diagnostic controllers and test benches as intermediary components that coordinate between the multiple scan paths and the analysis system. These intermediaries manage the complexity of coordinating multiple scan paths by providing a unified control interface and automated analysis logic, making the multi-path system easier to manage while maintaining its diagnostic precision
Data Source
AI summary
A method of performing root cause identification for a failure on an integrated circuit with a logic built-in self-test (LBIST) system and an LBIST system to perform root cause identification are described. The system includes one or more channel scan paths, each of the one or more macros associated with each of the one or more channel scan paths being executed during a test cycle, and a processor to initiate one or more of the test cycles via an LBIST controller, identify a failing test cycle among the one or more of the test cycles, identify a failing channel scan path among the one or more channel scan paths for the failing cycle, identify the one or more macros associated with the failing channel scan path, and iteratively check each of the one or more macros associated with the failing channel scan path to perform the root cause identification.