Semiconductor Memory Bank Refresh Control for Data Retention
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Solution Overview
Problem
As the integration of memory in semiconductor devices increases, the coupling effect between word lines leads to word line disturbance, causing data degradation in memory cells, especially those connected to frequently activated word lines, due to increased activation frequency.
Innovation Solution
Implementing an additional refresh operation for memory banks with higher activation numbers, alongside normal refresh operations, to mitigate data degradation and reduce current consumption by selectively performing extra refreshes only on banks with higher activation frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the distance between word lines is reduced to increase integration degree, then memory integration increases, but coupling effect between adjacent word lines increases causing data degradation
Solution Approach 1:
The patent performs preliminary detection of word line activation frequency and proactively applies additional refresh operations to frequently activated word lines before data degradation occurs. The refresh control block monitors activation patterns and preemptively refreshes vulnerable memory cells, preventing the coupling effect from causing data loss.
Solution Approach 2:
The patent applies different refresh strategies to different word lines based on their individual activation frequencies. Instead of uniform refresh across all banks, the system identifies specific frequently activated word lines and applies targeted additional refresh operations only to those regions, optimizing both data retention and power consumption.
2Reliability
If additional refresh operations are performed on frequently activated banks, then data degradation is prevented, but current consumption increases
Solution Approach 1:
The patent applies additional refresh operations selectively only to banks with frequently activated word lines, rather than performing uniform refresh across all banks. The refresh control block identifies specific banks requiring additional refresh based on activation frequency detection, thereby preventing data degradation in vulnerable areas while avoiding unnecessary current consumption in already-stable banks.
Solution Approach 2:
The patent performs partial additional refresh operations on specific banks that exhibit high activation frequency, rather than applying excessive refresh to all banks. This partial action approach provides sufficient refresh coverage for vulnerable memory cells while minimizing overall current consumption by limiting additional refresh operations to only where needed.
3Reliability
If uniform refresh operation is performed on all banks, then data retention is maintained, but current consumption increases unnecessarily
Solution Approach 1:
The patent transitions from uniform refresh across all banks to localized selective refresh based on actual activation frequency patterns. The refresh control block detects which specific banks experience frequent word line activation and applies additional refresh operations only to those banks, maintaining data retention reliability while significantly reducing unnecessary current consumption in banks with low activation frequency.
Solution Approach 2:
The system enables banks to self-identify their refresh needs through the activation frequency detection mechanism. Banks with high activation frequencies automatically trigger additional refresh operations through the refresh control block, while banks with low activation frequencies naturally receive only standard refresh operations, eliminating the need for centralized uniform refresh control.
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 prevents data degradation in memory cells by enhancing refresh operations for frequently activated word lines while minimizing additional current consumption by targeting only those banks with higher activation frequencies.
Implementation Method 1
a counting block suitable for counting the activation number of the respective banks, and selecting a bank having the activation number larger than or equal to a given number
Implementation Method 2
the amount of charges charged in the cell capacitors CAPL−1 and CAPL+1 is affected so that the data of the memory cells CL−1 and the CL+1 may be degraded
Implementation Method 3
a coupling effect between adjacent word lines increases
Implementation Method 4
as electromagnetic waves, which are generated while the word line toggles between the activated state and the deactivated state, introduce/discharge electrons into/from the cell capacitors of the memory cells connected with adjacent word lines
Data Source
AI summary
A semiconductor memory device includes a plurality of banks; a counting block suitable for counting the activation number of the respective banks, and selecting a bank of which the activation number is larger than or equal to a given number; and a refresh control block suitable for performing a normal refresh operation on the banks in response to a refresh command, and performing an additional refresh operation N times on the selected bank, N being a positive integer.