DRAM Row Repair Using Dynamic Spare Row Mapping
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Solution Overview
Problem
Existing DRAM repairing techniques are limited by a lack of sufficient spare rows, leading to permanent errors and the need for manual replacement of faulty DRAMs/DIMMs, as current methods cannot effectively manage multi-bit errors and correctable errors beyond a threshold.
Innovation Solution
A method and system that dynamically increase the number of spare rows in DRAMs by reserving memory space using a BIOS boot menu, identify faulty rows, classify them as correctable or uncorrectable, and map correctable rows to available spare rows, updating error information and translation tables, and copy data to spare rows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional PPR techniques are used with limited spare rows, then manufacturing complexity is reduced, but reliability deteriorates when all spare rows are exhausted
Solution Approach 1:
The patent implements dynamic spare row management where the system transitions from static traditional PPR to a dynamic approach using multiple spare row pools and runtime mapping. The memory controller dynamically selects from multiple spare row pools based on fault location and type, and the mapping tables are updated in real-time during operation, allowing the system to adapt to different failure scenarios and maximize the utilization of available spare capacity.
Solution Approach 2:
The patent segments the spare row resource into multiple pools (first spare row pool, second spare row pool, third spare row pool) with different characteristics and capacities. Each pool can be independently managed and allocated to different bank groups or fault types. This segmentation allows the system to optimize the use of each pool according to specific requirements, thereby improving overall reliability without requiring a single large complex spare row structure.
2Reliability
If the number of spare rows is increased to repair more faulty rows, then reliability is improved, but manufacturing complexity and device cost increase
Solution Approach 1:
The patent creates a universal spare row management system where multiple spare row pools serve multiple functions: the first pool handles standard repairs, the second pool provides additional capacity, and the third pool offers backup capability. The mapping tables and selection logic are designed to be universal, working across different bank groups and fault types. This multi-functionality allows the system to achieve high reliability with a structured approach rather than simply increasing the total number of spare rows indiscriminately.
Solution Approach 2:
The patent changes the parameters of spare row management by introducing multiple pools with different capacities and allocation rules. Instead of using a single pool with fixed parameters, the system adjusts parameters dynamically - selecting different pools based on fault characteristics, updating mapping tables with new parameters, and adapting the allocation strategy. This parameter-based approach allows flexible optimization of reliability versus complexity trade-offs.
3Reliability
If manual replacement is performed when spare rows are exhausted, then reliability is maintained, but productivity and time efficiency deteriorate
Solution Approach 1:
The patent implements preliminary action by pre-configuring multiple spare row pools and establishing mapping tables before faults occur. The system proactively reserves spare capacity in advance and sets up the infrastructure for rapid fault response. When faults are detected, the pre-established pools and mapping mechanisms enable immediate repair operations without requiring manual intervention or system downtime, thus maintaining both reliability and productivity.
Solution Approach 2:
The patent enables self-service repair capability where the memory controller automatically detects faults, selects appropriate spare rows from the pools, updates mapping tables, and completes the repair process without external intervention. The system serves itself by monitoring its own health status and autonomously executing repair operations using the multi-pool spare row structure, eliminating the need for manual replacement and associated downtime.
4Productivity
If dynamic spare row management is implemented, then productivity and adaptability are improved, but device complexity increases
Solution Approach 1:
The patent introduces intermediary structures - the error information table and mapping tables - that mediate between the complex multi-pool spare row system and the fault repair process. These intermediary tables store and organize fault information, spare row allocations, and mapping relationships, simplifying the management complexity by providing structured interfaces. The mapping tables act as intermediaries that translate fault locations to appropriate spare rows, reducing the complexity of direct management while enabling efficient automated repair operations.
Data Source
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AI summary
Various example embodiments are directed to a method, device, and system for repairing a Dynamic Random Access Memory (DRAM) memory device. The method includes reserving a memory space within the DRAM memory device, the reserved memory space including a plurality of spare rows, identifying one or more faulty rows within the DRAM memory device using at least one memory testing method, updating an error information table based on information of a respective classified correctable faulty row, in response to an error count for the respective classified correctable faulty row exceeding a desired threshold value, mapping the respective classified correctable faulty row to an available spare row of the plurality of spare rows, storing the mapping of the respective correctable faulty row and the mapped spare row in a row repair translation table, and copying data stored in the respective correctable faulty row into the mapped spare row.