Flash Memory Dummy Word Line for Program Disturb
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Solution Overview
Problem
In NAND flash memory systems, unintended programming of unselected cells, known as 'program disturb,' occurs due to the application of program voltage to all cells connected to a word line, leading to inefficiencies and potential errors in data storage.
Innovation Solution
The introduction of a dummy word line between the source side select element and the first word line, allowing a program voltage to be applied only to the selected non-volatile storage element while an intermediate voltage is applied to the dummy word line, effectively isolating and reducing the risk of unintended programming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If program voltage is applied to all cells connected to a word line for programming, then programming operation can be performed, but unintended programming of unselected cells occurs causing program disturb
Solution Approach 1:
The patent segments the word line structure by introducing a dummy word line between the source side select element and the first word line. This segmentation allows independent voltage control of different cell groups, enabling selective programming while preventing program disturb in unselected cells through isolated voltage application.
Solution Approach 2:
The dummy word line acts as an intermediary element that mediates between the source side select element and the first word line. By applying intermediate voltage to this intermediary structure, the patent controls the potential distribution to prevent harmful GIDL effects in unselected cells while maintaining programming capability in selected cells.
2Manufacturing precision
If program voltage is applied to selected non-volatile storage element, then accurate programming can be achieved, but Gate Induced Drain Leakage occurs in unselected cells
Solution Approach 1:
The patent applies different voltage levels to different spatial regions: high program voltage to the selected cell's word line for accurate programming, and intermediate voltage to the dummy word line region to suppress GIDL. This local differentiation of voltage quality eliminates harmful leakage while maintaining programming precision.
Solution Approach 2:
The dummy word line structure provides preliminary protection against GIDL by establishing an intermediate voltage potential before the harmful leakage can occur in unselected cells. This preventive measure counteracts the harmful electric field effects before they can cause damage.
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 solution reduces Gate Induced Drain Leakage (GIDL) and minimizes program disturb, enhancing the accuracy and efficiency of programming operations by isolating the channel of unselected cells, thereby improving data storage reliability.
Implementation Method 1
This solution reduces Gate Induced Drain Leakage (GIDL) and minimizes program disturb, enhancing the accuracy and efficiency of programming operations by isolating the channel of unselected cells
Data Source
AI summary
Method and system for memory devices is provided. The system includes a plurality of non-volatile storage elements connected in a string between a source side element and a drain side element; a plurality of bit lines, wherein each bit line is connected to a plurality of non-volatile storage elements; and a plurality of word lines, the plurality of word lines include a dummy word line between a source side select element and a first word line that is connected to a first non-volatile storage element to be programmed, wherein a program voltage is applied to the first non-volatile storage element connected to the first word line and an intermediate voltage is applied to a second non-volatile storage element connected to the dummy word line.