Memory Device Dummy Word Line Segmentation
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Solution Overview
Problem
In semiconductor memory devices with high aspect ratios, incomplete etching leads to issues like slow programming, charge loss, and charge gain due to electrical connections between conductor layers, which affect the gate coupling ratio and raw bit error rate.
Innovation Solution
The method involves forming groups of word lines and dummy word lines on a substrate, where both are applied operational voltages simultaneously to maintain the same potential, even if connections occur due to etching limitations, thereby preventing potential drops and improving programming efficiency and error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of the memory cell is reduced to achieve high density, then the storage capacity increases, but the critical dimension of the floating gate becomes limited and incomplete etching occurs
Solution Approach 1:
The patent divides the word line structure into multiple segments by introducing dummy word lines between adjacent word lines. This segmentation prevents incomplete etching from causing electrical connections between adjacent conductor layers, as each dummy word line acts as an isolated segment that maintains proper electrical isolation even when etching is imperfect.
Solution Approach 2:
Dummy word lines serve as intermediary structures between adjacent word lines. These intermediary elements prevent direct electrical connection between word lines through incomplete etching, acting as a mediator that maintains proper electrical isolation while allowing the overall device to achieve high density.
2Device complexity
If conventional word line structures are used, then the device structure is simple, but slow programming, charge loss, and charge gain occur due to incomplete etching
Solution Approach 1:
The word line structure is segmented into alternating word lines and dummy word lines. This segmentation isolates electrical issues to individual segments, preventing charge loss or gain from affecting the entire word line structure. Each segment can be independently controlled and maintained at proper potentials.
Solution Approach 2:
Different regions of the device have different structures - actual word lines for data operations and dummy word lines for isolation. This local differentiation allows the device to maintain simple operation protocols while having enhanced reliability in critical areas where incomplete etching might occur.
3Ease of operation
If voltages are applied to word lines with incomplete etching, then electrical operations can be performed, but potential drops occur and interference between word lines increases
Solution Approach 1:
Adjacent word lines and dummy word lines are maintained at the same potential through simultaneous voltage application. This equipotential condition prevents potential drops and eliminates electric field differences that would cause charge leakage or interference between adjacent word lines, even when incomplete etching creates conductive paths.
Solution Approach 2:
The patent applies preliminary protective action by establishing equipotential conditions before electrical operations occur. By ensuring adjacent lines are at the same potential beforehand, the design prevents harmful effects like charge loss or word line interference from occurring during normal operation.
Data Source
AI summary
A memory device and a method for operating the same are provided. The memory device includes a substrate, a plurality of word lines, and a plurality of dummy word lines. The word lines and the dummy word lines are located on the substrate. At least one side of each dummy word line is adjacent to the word line. At least one word line and at least one dummy word line form a group. The method for operating the memory device includes the following. At least one group is selected, and the group is operated. A first operational voltage is applied to the word line of the group. A second operational voltage is applied to the dummy word line of the group.