Die-Scope Proximity Disturb Remapping for NVM
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In non-volatile memory, the reduction in physical isolation between storage elements leads to defects such as high read and write error rates due to disturb coupling, which existing methods mitigate at the cost of increased complexity, cost, or performance.
Innovation Solution
A die-scope proximity disturb and defect remapping scheme that remaps defective storage elements to spare locations while minimizing the introduction of new proximal disturb relationships, using a subslice element status map and substitution data structure to identify and redirect user subslice elements with high error rates to available spare subslice elements within the same or across dice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If storage elements are forced closer together to achieve smaller products, then product size is reduced, but physical isolation between storage elements decreases leading to increased disturb coupling and error rates
Solution Approach 1:
The memory array is divided into multiple sub-arrays, and defective storage elements are remapped to spare elements within the same sub-array. This segmentation ensures that remapped elements remain physically close to their original neighbors, maintaining similar disturb coupling characteristics while avoiding the introduction of new disturb relationships with distant elements.
Solution Approach 2:
The patent creates a mapping structure that copies the physical neighbor relationships from the original array layout to the remapped spare elements. By preserving the same neighbor set for remapped elements as for the original defective elements, the system maintains identical disturb coupling patterns without introducing new harmful interactions.
2Device complexity
If defect remapping is performed without considering proximal disturb relationships, then defect remediation is simplified, but new proximal disturb relationships are introduced increasing complexity
Solution Approach 1:
The system pre-identifies spare storage elements within each sub-array and establishes mapping relationships before defects occur. The mapping structure is prepared in advance, storing the physical addresses and neighbor relationships of spare elements, so that when defects are detected, remapping can be performed quickly without complex real-time calculations.
Solution Approach 2:
The remapping operation is constrained to operate locally within each sub-array rather than globally across the entire memory array. This local approach ensures that remapped elements remain within the same physical region and maintain the same neighbor relationships, preserving local disturb coupling characteristics while simplifying the remapping process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively manages defects and disturb coupling, maintaining performance by reducing error rates and minimizing the introduction of new disturb relationships, while being flexible and adaptable to changing error conditions over the lifetime of the memory device.
Implementation Method 1
For media that use a thermal process to encode the state of the storage element, such as phase change media, thermal effects propagate to surrounding storage elements. This document refers to these propagated thermal effects as disturb coupling.
Data Source
AI summary
Techniques for remapping portions of an array of non-volatile memory (NVM) resident on a die, in which the die is one of a plurality of NVM dice forming a memory device. A processing device partitions the NVM into a plurality of subslice elements comprising respective physical portions of non-volatile memory having proximal disturb relationships. The NVM has a first portion of the subslice elements allocated as user subslice elements and a second portion as spare subslice elements and the processing device performs an error analysis to identify a predetermined number of subslice elements having highest error rates for a memory domain on the die. For the identified subslice elements having the highest error rates, the processing device remaps user subslice elements to spare subslice elements that were not identified as having the highest error rates to remove subslice element or elements having highest error rates from a user space of the NVM.