NOR Flash Memory Cell Verification Current Control
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Solution Overview
Problem
Conventional NOR flash memory devices face issues with inadvertent elevation of wordline voltage during program verification operations, leading to erroneous interpretation of threshold voltages across memory cells, especially when a large number of cells require verification.
Innovation Solution
The method involves controlling the supply of current from sense amplifiers to memory cells based on the value of programmed data, enabling current supply only for cells requiring verification and disabling it for those that do not, to prevent voltage increases and ensure accurate program verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If program verification is performed simultaneously across a large block of memory cells, then verification throughput is improved, but voltage elevation on source lines causes measurement precision to deteriorate
Solution Approach 1:
The patent segments the verification process by dividing the block of memory cells into multiple sub-blocks or groups. Instead of verifying all cells simultaneously across the entire block, the verification is performed in segmented portions, allowing current to be distributed and controlled more effectively, thereby preventing excessive voltage elevation on source lines while maintaining reasonable verification throughput
Solution Approach 2:
The patent applies local quality by selectively enabling verification for specific memory cells or regions within the block based on their individual requirements. Rather than uniformly verifying all cells, the system identifies and verifies only those cells that need verification, applying different verification strategies to different local regions, thus reducing overall current consumption and preventing voltage elevation in areas where it is not needed
2Reliability
If current is supplied to all memory cells during program verification, then verification coverage is improved, but current consumption increases causing voltage elevation and erroneous threshold voltage interpretation
Solution Approach 1:
The patent applies partial action by supplying current only to the extent necessary for verification. Instead of providing full current to all memory cells in the block, the system provides partial current only to those specific cells that require verification, avoiding excessive current consumption that would cause voltage elevation while still achieving sufficient verification coverage
Solution Approach 2:
The patent employs feedback mechanisms to dynamically control current supply during verification. The system monitors the state of memory cells and adjusts current supply accordingly, providing current only when and where verification is actually needed based on feedback from previous programming operations or cell state detection, thereby optimizing the balance between verification coverage and current consumption
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 prevents voltage elevation on source lines, thereby ensuring accurate program verification results and avoiding errors in identifying the intended program states of memory cells.
Implementation Method 1
controlling the supply of current from a sense amplifier to the memory cell in relation to the value of the programming data
Data Source
AI summary
A NOR flash memory device and related programming method are disclosed. The programming method includes programming data in a memory cell and, during a program verification operation, controlling the supply of current from a sense amplifier to the memory cell in relation to the value of the programmed data. Wherein a program verification operation is indicated, current is provided from the sense amplifier to the memory cell. Where a program verification operation is not indicated, current is cut off from the sense amplifier.