Flash Memory Multi-Plane Programming Disturbance Control
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Solution Overview
Problem
Conventional NAND-type flash memory devices experience program disturbance during multi-plane programming, where program and pass voltages are applied to all planes, including program-passed planes, leading to increased threshold voltages and potential read errors.
Innovation Solution
A flash memory device with a voltage generator circuit producing program, pass, and high voltages, and control logic that interrupts these voltages to program-passed planes based on verification results, preventing undue stress and disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If program and pass voltages are applied to all planes during multi-plane programming, then programming operation can be performed across multiple planes simultaneously, but program disturbance occurs in program-passed planes causing threshold voltage increase and read errors
Solution Approach 1:
The patent segments the plane set into program-passed planes and program-failed planes based on verification results. Control logic then selectively applies program and pass voltages only to program-failed planes, while interrupting voltage application to program-passed planes. This segmentation resolves the contradiction by maintaining multi-plane programming capability while preventing program disturbance in successfully programmed planes.
Solution Approach 2:
Instead of applying program and pass voltages to all planes (excessive action), the patent applies these voltages only to the subset of planes that actually need programming (partial action). The control logic determines which planes are program-failed and restricts voltage application to only those planes, thereby avoiding unnecessary stress on program-passed planes while maintaining overall programming efficiency.
2Reliability
If program operation is repeated until all planes pass verification, then all planes can be ensured to be programmed normally, but program-passed planes suffer from repeated voltage application causing soft programming and threshold voltage shift
Solution Approach 1:
The patent extracts program-passed planes from the set of planes receiving program and pass voltages. After verification identifies which planes have successfully programmed, the control logic removes program-passed planes from the voltage application group, applying these voltages only to program-failed planes. This extraction eliminates the harmful effect of repeated voltage application on already-successful planes while ensuring program-failed planes receive necessary programming stress.
Solution Approach 2:
The patent implements a feedback mechanism where verification results from each plane are fed back to the control logic, which then adjusts voltage application accordingly. The control logic uses verification feedback to determine whether to continue applying program and pass voltages to each plane, interrupting voltage application to program-passed planes and maintaining it for program-failed planes. This feedback-based control resolves the contradiction by dynamically adjusting voltage application based on actual programming status.
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
The solution effectively reduces program disturbance by preventing the application of program and pass voltages to program-passed planes, ensuring accurate data reading and reducing errors during multi-plane programming.
Implementation Method 1
memory cells may be programmed or erased by use of the Fowler-Nordheim (FN) tunneling current
Data Source
AI summary
A flash memory device that includes a voltage generator circuit configured to generate a program voltage, a pass voltage, and a high voltage; a plurality of planes configured to perform a program operation in response to the program, pass, and high voltages and to verify the program operation, respectively; and control logic configured to control the planes in response to verification results from the planes, wherein the control logic controls the planes so as to interrupt the program and pass voltages or the high voltage from being applied to program-passed planes.