Nitride Memory Read Voltage Biasing to Suppress Coupling Interference
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Solution Overview
Problem
Miniaturization of nitride-based memory cells leads to coupling interference issues, causing threshold voltage shifts and narrowing operation windows due to close proximity of word lines, which affects data storage and retrieval operations.
Innovation Solution
Applying specific voltage configurations to adjacent word lines during reading operations, including a first positive voltage to one side and a second positive voltage to the other side of the selected memory cell, along with appropriate gate, source/drain, and substrate voltages, to reduce coupling interference and maintain stable threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cell size is miniaturized to increase storage density, then storage capacity is improved, but coupling interference between adjacent word lines increases causing threshold voltage shifts
Solution Approach 1:
The patent applies preliminary anti-action by applying positive voltages to adjacent word lines before and during the read operation of the selected memory cell. This preemptive action creates a protective electric field that counteracts the coupling interference from neighboring word lines, preventing threshold voltage shifts before they occur. The method proactively neutralizes the harmful electrostatic influence rather than reacting to it after the fact.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the voltage parameters of adjacent word lines during read operations. Specifically, positive voltages (Vp1 and Vp2) are applied to adjacent word lines WL(i-1) and WL(i+1) when reading from selected word line WL(i). This parameter modification changes the electric field distribution to compensate for miniaturization effects, maintaining threshold voltage stability despite reduced cell dimensions.
2Length of moving object
If spacing between adjacent word lines is reduced to enable miniaturization, then device density is improved, but coupling interference increases resulting in threshold voltage shifts
Solution Approach 1:
The patent uses an intermediary approach by introducing controlled positive voltages on adjacent word lines as a mediating mechanism. These voltage applications create an intermediate electric field state that shields the selected memory cell from harmful coupling effects. The adjacent word lines act as intermediaries that, when properly biased, reduce the direct electrostatic coupling between the selected cell and its neighbors, thereby mitigating interference despite close spacing.
Solution Approach 2:
The patent applies parameter changes by modifying the voltage parameters of adjacent word lines to compensate for reduced spacing. When word lines are closely spaced, the patent applies positive voltages Vp1 and Vp2 to adjacent word lines during read operations, changing the electric field parameters to maintain adequate isolation. This dynamic parameter adjustment ensures that coupling interference remains controlled even when physical spacing is minimized for density improvements.
3Reliability
If positive voltage is applied to adjacent word lines to reduce coupling interference, then threshold voltage stability is improved, but additional voltage control complexity is introduced
Solution Approach 1:
The patent applies segmentation by dividing the voltage control function into distinct segments: the selected word line receives the primary read voltage, while adjacent word lines receive separate positive bias voltages (Vp1 and Vp2). This segmented approach allows independent control of each word line's voltage state, simplifying the overall control logic by treating interference mitigation as a separate, standardized function that can be implemented through dedicated voltage sources rather than complex interdependent control circuits.
Data Source
AI summary
An operation method of a non-volatile memory is provided. The operation method is that a reading operation is performed to a selected nitride-based memory cell, a first positive voltage is applied to a word line adjacent to one side of the selected memory cell and a second positive voltage is applied to another word line adjacent to the other side of the selected memory cell. The operation method of this present invention not only can reduce a coupling interference issue but also can obtain a wider operation window.