Multichip Module Reroutable Inter-Die I/O Connections
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Solution Overview
Problem
The yield of multichip modules (MCMs) is limited by defects in inter-die I/O connections, which are prone to defects, leading to higher production costs and lower functionality in complex systems with irregular structures or specific I/O connection points.
Innovation Solution
Implementing redundant I/O connections between dice on a MCM, with circuitry to reroute signals from defective connections to redundant ones, either during fabrication or at power-up, and storing test results in nonvolatile memory for configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant I/O connections are implemented between dice on a MCM, then the yield of MCMs is significantly enhanced by ensuring only functional connections are used, but the device complexity increases due to additional connections and rerouting circuitry
Solution Approach 1:
The patent applies preliminary action by testing I/O connections during fabrication or at power-up before normal operation begins. Test results are stored in nonvolatile memory, and rerouting configurations are pre-established so that when defective connections are detected, the system can immediately switch to redundant connections without complex runtime decision-making, thus managing complexity while improving yield
Solution Approach 2:
The patent introduces an intermediary rerouting circuit that sits between the cores and the I/O connections. This intermediary contains logic that monitors connection status and automatically switches traffic from defective connections to redundant ones, isolating the complexity of defect management from the core functionality while maintaining high yield
2Reliability
If the number of inter-die I/O connections is increased to include redundant connections, then defective connections can be avoided through rerouting, but the manufacturing cost increases
Solution Approach 1:
The patent changes the parameter of connection multiplicity by implementing multiple redundant I/O connections between dice. By increasing the number of available connection paths, the system can tolerate defects in individual connections while maintaining overall functionality, thus improving reliability despite the increased manufacturing cost of additional connection infrastructure
3Reliability
If testing of I/O connections is performed after MCM assembly, then defective connections can be identified and avoided, but the productivity of the manufacturing process decreases
Solution Approach 1:
The patent performs the testing action preliminarily, either during the fabrication process or at power-up before the MCM enters normal operational mode. By completing the testing and configuration of redundant connections in advance, the patent avoids the need for time-consuming testing and rerouting during operation, thus minimizing the impact on manufacturing productivity while still achieving high yield through defect identification and avoidance
Data Source
AI summary
A multichip module (MCM) has redundant I/O connections between its dice. That is, the number of inter-die I/O connections used is larger than the number of connections ordinarily used to provide connectivity between the dice. Defective connections are discovered through testing after MCM assembly and avoided, with signals being rerouted through good (e.g., not defective) redundant connections. The testing can be done at assembly time and the results stored in nonvolatile memory. Alternatively, the MCM can perform the testing itself dynamically, e.g., at power up, and use the test results to configure the inter-die I/O connections.