Non-volatile Memory Voltage Boosting for Read Speed
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Solution Overview
Problem
Non-volatile memory read operations are hindered by the slow boosting of voltage on unselected word lines to a pass voltage, which affects the effectiveness and speed of data retrieval in 3D flash memory devices.
Innovation Solution
A method involving a first voltage with a greater slope applied to unselected word lines, which rises to a predetermined voltage higher than the pass voltage, and then transitions to a second voltage with a lower slope, ensuring the unselected word lines reach a voltage greater than 85% of the pass voltage efficiently, utilizing a comparator and drive circuits to manage the voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a voltage is supplied to unselected word lines to boost their voltage to pass voltage during read operation, then the memory cells can be turned on for correct read operation, but the voltage boosting is too slow due to magnitude or duration of supplied voltage
Solution Approach 1:
The patent applies periodic action by using a two-stage voltage boosting process. First, a first voltage with a first slope is applied to rapidly charge the unselected word lines. Then, a second voltage with a second slope is applied to complete the charging to pass voltage. This periodic application of different voltages resolves the contradiction by achieving both fast initial boosting and reliable final voltage level.
Solution Approach 2:
The patent changes voltage parameters (magnitude and slope) in two stages. The first voltage has a higher magnitude and steeper slope for rapid initial charging. The second voltage has lower magnitude and gentler slope for precise final charging to pass voltage. This parameter change strategy enables both fast voltage boosting and reliable read operation.
2Speed
If a high voltage is applied to unselected word lines to rapidly boost voltage, then voltage boosting speed increases, but overcharging may occur leading to incorrect operation
Solution Approach 1:
The patent segments the voltage boosting process into two distinct stages. The first stage applies a high voltage with steep slope for rapid charging up to a first threshold. The second stage applies a lower voltage with gentler slope to complete charging to pass voltage. This segmentation prevents overcharging while maintaining fast boosting speed.
Solution Approach 2:
The patent uses feedback control by monitoring the voltage on unselected word lines and switching between first and second voltages based on whether the pass voltage is reached. This feedback mechanism ensures accurate voltage control, preventing overcharging while achieving rapid voltage boosting.
3Reliability
If the duration of voltage supply to unselected word lines is extended to ensure sufficient charging, then voltage magnitude can be adequate, but the read operation time increases
Solution Approach 1:
The patent uses periodic action with two distinct voltage application phases. The first phase applies high voltage for a short duration to achieve rapid initial charging. The second phase applies lower voltage to complete the charging process. This reduces the total time compared to using only low voltage throughout, while ensuring sufficient charging.
Solution Approach 2:
The patent performs preliminary action by applying the first voltage with steep slope to rapidly charge the unselected word lines to a significant portion of pass voltage before applying the second voltage. This preliminary high-voltage charging reduces the remaining charging time, resolving the contradiction between voltage sufficiency and operation time.
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 approach accelerates the voltage rise on unselected word lines to the pass voltage, enhancing the speed and accuracy of read operations in non-volatile memory, preventing overcharging and ensuring timely data retrieval.
Implementation Method 1
applying a first voltage rising at a first slope to unselected word lines among a plurality of word lines to charge the unselected word lines
Implementation Method 2
electrons move between channels and floating gates of memory cells through an FN tunneling mode when a program (write) operation is performed
Data Source
AI summary
The present application discloses a non-volatile memory and an operating method of the non-volatile memory. The non-volatile memory includes a plurality of memory cells, and unselected word lines connected with the memory cells. The method includes applying a first voltage rising at a first slope to unselected word lines to charge the unselected word lines, and stopping applying the first voltage to the unselected word lines in response to that the first voltage rises to a predetermined voltage. The predetermined voltage is higher than a pass voltage of a plurality of memory cells connected with the unselected word lines.