Die-Based Rank Remapping for Memory Packages With Defective Dies
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Solution Overview
Problem
In memory devices with multiple dies, if one die is defective, the entire package is often discarded, reducing the available pool of high-density memory devices and increasing production costs due to the need to discard otherwise usable dies.
Innovation Solution
Implement a die-based rank controller that remaps memory addresses from nonfunctional dies to functional dies, enabling continued operation of the memory device by correlating or mapping rank selections to viable dies, thereby avoiding nonfunctional ranks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a die-based rank controller with remapping capability is implemented, then the reliability and usability of memory devices with defective dies is improved, but the device complexity increases due to additional control logic and storage elements
Solution Approach 1:
A die-based rank controller is introduced as an intermediary component between the memory address interface and the memory dies. The controller includes a storage element that stores mapping information correlating rank selections to specific dies, and logic that uses this mapping to redirect memory accesses away from defective dies to functional dies, thereby resolving the contradiction by adding controlled complexity that enables reliability improvement
2Productivity
If rank remapping is implemented to avoid nonfunctional dies, then the productivity and effective yield of memory production is improved, but the manufacturing precision requirements increase due to the need for accurate die functionality testing and mapping
Solution Approach 1:
The system performs preliminary testing of individual die functionality during manufacturing and stores the results in the controller's storage element as mapping information. This preliminary action identifies which dies are functional before the memory device is deployed, enabling the remapping logic to automatically route accesses to functional dies and thereby improve effective yield while managing manufacturing precision requirements through advance characterization
Data Source
AI summary
This document describes apparatuses and techniques for die-based rank management for a memory system. In various aspects, a die-based rank controller (controller) can determine which memory dies of a memory device are not functional to store data and correlate rank selections of a memory system to ranks of other memory dies (e.g., functional memory dies). The controller may store information that indicates the correlation or mapping of the rank selections to the ranks of the other memory dies to enable access to those ranks of the memory system. In some aspects, the controller receives a command to access the memory device with a rank selection, and the controller enables access to a corresponding rank based on the information. By so doing, aspects of die-based rank management enable memory packages with non-functional memory dies to be used instead of discarded, which can increase production utilization or lower manufacturing costs.