Flash Memory Programming Method Narrowing Threshold Voltage Distribution
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Solution Overview
Problem
Non-volatile memory arrays, such as flash memory, face issues with threshold voltage distribution margins being too wide, leading to read errors due to variations in physical properties of memory cells, which are exacerbated by neighbor and coupling effects during conventional programming methods.
Innovation Solution
A programming method involving two sequential programming operations: a first programming command followed by a second programming command, which helps to narrow the threshold voltage distribution margin by eliminating leakage currents and reducing charge interference between adjacent cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single programming operation is used, then programming speed is maintained, but threshold voltage distribution margin becomes wide leading to read errors
Solution Approach 1:
The programming operation is divided into two sequential programming operations instead of one single operation. The first programming operation programs the target memory cell, and the second programming operation re-programs the same target cell. This segmentation allows the threshold voltage distribution to be narrowed through the combined effect of both operations, improving manufacturing precision without sacrificing programming speed
Solution Approach 2:
The first programming operation serves as a preliminary action that prepares the memory cell for the second programming operation. By performing the first programming operation first, the memory cell is pre-configured in a way that enables the second operation to further narrow the threshold voltage distribution margin, thereby improving the final precision of threshold voltage control
2Reliability
If memory cells are programmed with same data, then data storage is achieved, but physical property variations cause threshold voltage differences
Solution Approach 1:
The second programming operation acts as a feedback mechanism that compensates for the threshold voltage variations caused by physical property differences among memory cells. By re-programming the target cell with the same data in the second operation, the system corrects the threshold voltage deviations, ensuring more uniform threshold voltages across all cells storing the same data
Data Source
AI summary
A programming method applied to a memory is provided. The memory includes a number of memory cells. The method includes the following steps. A target cell of the memory cells is programmed in response to a first programming command. The target cell is programmed in response to a second programming command.