Post-Package Repair Protection Circuit for Semiconductor Memory
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Solution Overview
Problem
Semiconductor memory devices face issues with defective rows that become inaccessible after packaging, leading to potential unintended changes during post-package repair (PPR) operations due to uncontrolled ACT commands and signals.
Innovation Solution
Incorporating an ACT mask circuit that suppresses further activations of ACT signals when in PPR mode, and a PPR function circuit to monitor internal signals and prevent simultaneous fuse blow operations, ensuring controlled PPR operations and protecting the memory device from inadvertent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the memory device operates in PPR mode to repair defective rows, then the device can redirect addresses from defective rows to redundant rows, but the device may inadvertently perform illegal commands that cause unintended changes to the device
Solution Approach 1:
The patent applies preliminary anti-action by implementing an ACT mask circuit that proactively prevents illegal ACT commands from being executed during PPR mode. The circuit masksthe ACT signal path before any unintended changes can occur, thereby preventing the harmful effect of illegal commands while maintaining the beneficial PPR functionality
Solution Approach 2:
The patent introduces an intermediary ACT mask circuit between the command decoder and the memory array. This intermediary component monitors and controls ACT signal activation during PPR mode, allowing legitimate PPR operations while blocking illegal commands that could cause unintended changes to the device
2Productivity
If multiple ACT signals are activated simultaneously during PPR operations, then more defective rows can be repaired, but fuse blow operations may occur simultaneously causing damage to the memory device
Solution Approach 1:
The patent applies preliminary action by implementing a PPR function circuit that monitors internal PPR signals and detects when multiple fuse blow operations are attempted simultaneously. The circuit takes preliminary protective action by disabling further PPR operations once simultaneous fuse blow is detected, preventing damage before it occurs
Solution Approach 2:
The patent implements feedback through the PPR function circuit that continuously monitors the state of internal PPR signals. When the feedback indicates that multiple fuse blow operations are occurring simultaneously, the circuit responds by disabling the PPR function, thereby preventing the harmful effect while allowing controlled parallel repair operations
Data Source
AI summary
Apparatuses and methods for post-package repair (PPR) protection. A device may enter a PPR mode to repair one or more memory addresses by blowing fuses. However, fuses may be incorrectly blown if the device receives row activation (ACT) signals while in the PPR mode. A PPR mask circuit may provide a PPR mask signal if an ACT signal is received while the memory is in the PPR mode. The PPR mask signal may suppress further ACT signals from being provided. In some embodiments, the memory may also include a PPR function circuit, which may monitor one or more signals used as part of PPR operations. If these signals are in an illegal state, the PPR function circuit may suppress PPR operations to prevent damage to the fuse array.