Memory Row Access Count Updates for Row Hammer Mitigation
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Solution Overview
Problem
As memory components decrease in size, the density of memory cells increases, leading to an elevated rate of data degradation in nearby cells due to repeated access, known as 'row hammering, which can result in information loss if not adequately addressed.
Innovation Solution
Implementing an access count update (ACU) mechanism that tracks access counts for each row using ACU command codes to identify aggressor rows and perform targeted refresh operations, adjusting access counts to mitigate row hammering effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory components decrease in size to increase density, then storage capacity increases, but data degradation rate in nearby cells increases due to row hammering
Solution Approach 1:
The patent segments the access count tracking by implementing separate counters for victim rows and aggressor rows. This segmentation allows the system to independently monitor and manage access patterns for different row types, enabling targeted refresh operations that address row hammering effects without affecting overall memory performance.
Solution Approach 2:
The patent implements preliminary action by performing access count updates and refresh operations before data degradation becomes critical. The system proactively identifies rows with high access counts and refreshes them in advance, preventing data loss rather than reacting after degradation occurs.
2Reliability
If access count tracking is implemented to identify aggressor rows, then targeted refresh operations can be performed, but device complexity increases
Solution Approach 1:
The patent merges the access count update functionality with existing memory access operations. The access count update commands are integrated into the normal memory access flow, allowing the system to track and refresh rows without requiring separate dedicated hardware or complex control mechanisms.
Solution Approach 2:
The patent implements universal access count update commands that can handle multiple operations (increment, decrement, initialize) through a single unified command structure. This multi-functionality reduces the need for multiple specialized commands and simplifies the overall control logic.
3Measurement precision
If access counts are frequently updated to track row access patterns, then row hammering can be detected, but processing time increases
Solution Approach 1:
The patent implements periodic action by updating access counts at specific intervals or under certain conditions rather than continuously. The system periodically refreshes counters and performs access count updates only when necessary, reducing the time overhead while maintaining accurate detection of row hammering patterns.
Data Source
AI summary
Embodiments of the disclosure are drawn to apparatuses, systems, and methods for performing access count update (ACU) operations based on a value of an ACU command code. A memory may activate a word line. An access count value and an ACU command code may be read from counter memory cells and ACU command memory cells associated with the active word line. Based on the value of the ACU command code, an operation may be performed on the access count value. Based on the value of the ACU command code, the access count value may be changed in a first direction, changed in a second direction, or initialized. Using the ACU command code to preserve a portion of the access count value when a word line is refreshed may decrease the likelihood of information decay.