Memory Device Block Word Line Voltage Control
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Solution Overview
Problem
In memory devices, the potential difference between word lines and channels increases after a sensing operation, leading to shifting of threshold voltage distributions in memory cells, which can result in uncorrectable errors and memory cell degradation.
Innovation Solution
A memory device and method that control the voltage level applied to a block word line to reduce the potential difference by applying a turn-on voltage only during specific idle states after a recovery operation, thereby preventing the increase in word line potentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensing operation is performed on selected memory cells, then data can be read from the memory device, but the potential difference between word lines and channels increases causing threshold voltage distribution shifting
Solution Approach 1:
The patent applies preliminary anti-action by discharging the block word line before the sensing operation completes and before the recovery operation begins. This preemptive discharge prevents the potential difference from building up to harmful levels, thereby counteracting the threshold voltage distribution shifting before it can occur. The block word line is discharged to a reference voltage level during an idle state that is detected between the sensing and recovery operations.
2Manufacturing precision
If word lines are discharged after sensing operation, then potential difference is reduced, but recovery operation for channels is required which increases operation time
Solution Approach 1:
The patent implements preliminary action by performing the block word line discharge during the idle state that naturally occurs between the sensing operation and the recovery operation. This timing allows the discharge to happen without extending the critical sensing or recovery operation times, as the discharge utilizes the existing idle period. The idle state sensor detects when no operation is being performed on the memory cell array to trigger the discharge at this optimal moment.
3Stability of the object's composition
If turn-on voltage is continuously applied to block word line, then word line potentials are maintained, but potential difference with channels increases causing memory cell stress
Solution Approach 1:
The patent applies dynamics by making the block word line voltage state dynamic rather than static. The block word line alternates between being charged (during active operations) and discharged (during idle states) based on real-time operational conditions. The idle state sensor continuously monitors the operational state and dynamically adjusts the block word line voltage accordingly, switching between charged and discharged states to optimize both stability and stress reduction.
4Manufacturing precision
If block word line is discharged during idle state, then potential difference is reduced preventing threshold voltage shifting, but requires additional control circuitry
Solution Approach 1:
The patent implements universality by designing the idle state sensor and block word line control circuitry to serve multiple functions. The idle state sensor not only detects idle states for block word line discharge control but also provides status information for overall device operation management. The block word line controller integrates multiple control functions including discharge timing, voltage level management, and coordination with the sensing and recovery operations, thereby reducing the need for separate dedicated circuits for each function.
Data Source
AI summary
A memory device, and a method of operating the same, includes a memory cell array coupled to a plurality of word lines, wherein each word line is coupled to a plurality of memory cells. The memory device also includes a peripheral circuit configured to perform a sensing operation of sensing selected memory cells coupled to a selected word line selected from among the plurality of word lines. The memory device further includes control logic configured to control the peripheral circuit apply a turn-on voltage to a block word line coupled to the selected word line when the sensing operation is terminated and when potentials of the plurality of word lines are increased due to a recovery operation for channels of the plurality of memory cells after the plurality of word lines have been discharged.