Multi-bit Memory Read Compensation for Coupling-Induced Margin Loss
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Solution Overview
Problem
Multi-bit memory cells experience reduced read margin due to electric field coupling/F-poly coupling, leading to difficulties in accurately determining the data state of programmed memory cells, which conventional remedies often address by increasing the size and layout area of memory cell arrays.
Innovation Solution
A read operation method that compensates for read data from selected memory cells by considering the data states of adjacent memory cells affected by electric field coupling/F-poly coupling, using a memory controller to determine if compensation is needed and applying it to ensure accurate data state discrimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electric field coupling/F-poly coupling occurs between adjacent memory cells during programming, then programming efficiency is improved, but threshold voltage distributions expand and read margin is reduced
Solution Approach 1:
The patent implements a feedback mechanism where the memory controller reads data from adjacent memory cells to determine their data states, then uses this information to compensate for threshold voltage shifts in the selected memory cell. This feedback loop allows the system to detect and correct the harmful effects of electric field coupling, maintaining read margin while preserving programming efficiency.
Solution Approach 2:
The patent changes the parameter of threshold voltage by introducing compensation values based on the data states of adjacent cells. When electric field coupling causes threshold voltage expansion, the system adjusts the read threshold voltage parameter using compensation data from neighboring cells, thereby restoring accurate read margin without affecting the programming process.
2Reliability
If conventional remedies increase the size and layout area of memory cell arrays, then read margin is improved, but device area increases
Solution Approach 1:
The patent introduces an intermediary approach where the memory controller acts as a mediator between adjacent memory cells. Instead of physically separating cells to reduce coupling, the controller uses software-based compensation algorithms that process data from adjacent cells to correct threshold voltage shifts, thereby improving read margin without increasing physical area.
Solution Approach 2:
The patent replaces the mechanical approach of increasing physical spacing or area to reduce coupling effects with an electronic/software-based solution. The memory controller uses algorithms to compensate for electric field coupling effects, substituting physical redesign with computational correction to maintain read margin while preserving compact layout.
3Manufacturing precision
If smaller ISPP programming increments are used, then threshold voltage distribution accuracy is improved, but programming time increases
Solution Approach 1:
The patent applies preliminary action by reading data from adjacent memory cells before finalizing the read operation of the selected cell. This preliminary reading allows the system to pre-determine compensation values that will be applied during the actual read, ensuring accurate threshold voltage discrimination without requiring extended programming cycles.
Solution Approach 2:
The patent uses partial action by reading only the necessary data from adjacent cells (rather than all cells in the array) to determine compensation values. This selective reading provides sufficient information to correct threshold voltage shifts while minimizing the time overhead, balancing precision requirements with programming cycle efficiency.
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 improves read margin and reliability in multi-bit memory systems by accurately determining the programmed state of memory cells, even when threshold voltage distributions are expanded due to coupling, without increasing the size of memory cell arrays.
Implementation Method 1
electric field coupling or F-poly coupling
Implementation Method 2
electrical charge accumulates on the floating gate FG of memory cell MCB as it is programmed
Data Source
AI summary
Provided is a read operation for a N-bit data non-volatile memory system. The method includes determining in relation to data states of adjacent memory cells associated with a selected memory cell in the plurality of memory cells whether read data obtained from the selected memory cell requires compensation, and if the read data requires compensation, replacing the read data with compensated read data.