Flash Memory Programming Voltage Sequences
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Solution Overview
Problem
Existing nonvolatile memory devices face challenges in efficiently programming memory cells, particularly in preventing program disturbances and improving boosting efficiency in program-inhibited channels during the programming operation.
Innovation Solution
The method involves applying a local voltage to a first unselected word line, followed by a local voltage to a second unselected word line, and then a pass voltage to the first unselected word line, with specific voltage control sequences to optimize the programming process, including applying a program voltage to the selected word line after the pass voltage is reached, to minimize program disturbances and enhance boosting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional programming voltage is applied to the selected word line, then the programming operation can be performed, but program disturbances occur in program-inhibited channels
Solution Approach 1:
The patent segments the voltage application process into distinct phases: first applying local voltages to specific unselected word lines (WL3, WL5) to create potential barriers, then applying pass voltage to other unselected word lines, and finally applying the programming voltage to the selected word line. This segmentation allows different regions of the memory array to be controlled independently, enabling programming of selected cells while protecting program-inhibited channels from disturbances.
Solution Approach 2:
The patent applies preliminary local voltages to unselected word lines before applying the programming voltage to the selected word line. By pre-establishing potential barriers through local voltage application to WL3 and WL5, the patent prepares the memory array to prevent carrier injection into program-inhibited channels, thereby eliminating program disturbances before they can occur.
2Productivity
If the programming operation is performed without optimized voltage control, then the process is simple, but the boosting efficiency in program-inhibited strings is poor
Solution Approach 1:
The patent employs dynamic voltage control where the voltage levels and application timing are continuously optimized during the programming process. The controller dynamically adjusts the voltage sequence: applying local voltages to WL3 and WL5 first, then pass voltage to WL1 and WL2, and finally programming voltage to WL4. This dynamic approach maximizes boosting efficiency by ensuring proper voltage conditions are established at each stage, while the automated controller manages the complexity of the voltage sequence.
Data Source
AI summary
A programming method of a nonvolatile memory device is provided including: applying a local voltage to a first unselected word line; applying a local voltage to a second unselected word line, after the local voltage is applied to the first unselected word line; and applying a pass voltage to the first unselected word line, after the local voltage is applied to the second unselected word line. Related devices and systems are also provided herein.