Memory Device GIDL Hole Injection for Program Disturb Mitigation
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Solution Overview
Problem
Memory devices face challenges in improving electrical characteristics during program operations, particularly in maintaining channel potential levels of unselected strings, which can lead to program disturb phenomena.
Innovation Solution
The memory device employs a peripheral circuit and control logic to generate Gate Induced Drain Leakage (GIDL) at the channel under source or drain select transistors of unselected strings during hole injection operations, thereby increasing the channel potential level and mitigating program disturb issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional program operations are performed without hole injection, then the program operation speed is maintained, but the channel potential level of unselected strings decreases causing program disturb phenomena
Solution Approach 1:
The patent utilizes the Gate Induced Drain Leakage (GIDL) effect, which is typically considered a harmful leakage phenomenon, to generate holes that are injected into the channel of unselected strings. This converts the harmful GIDL effect into a beneficial mechanism for maintaining channel potential levels and preventing program disturb, thereby improving program operation reliability.
Solution Approach 2:
The hole injection operation is performed as a preliminary action before subsequent program operations on unselected strings. By injecting holes into the channel in advance, the channel potential level is maintained at an appropriate level, preventing program disturb phenomena from occurring during later programming operations.
2Reliability
If hole injection operation is performed to increase channel potential level, then program disturb phenomena are reduced, but the device operation complexity increases
Solution Approach 1:
The patent merges the hole injection operation with the existing program verify operation by performing hole injection when the program verify result indicates failure. This integration allows the hole injection to be incorporated into the standard program operation flow without requiring completely separate operational sequences, thereby managing device complexity while improving reliability.
3Reliability
If GIDL is generated at source select transistor channel, then channel potential is increased, but energy consumption increases
Solution Approach 1:
The patent applies GIDL generation locally at specific positions - either at the source select transistor channel or at the drain select transistor channel of unselected strings in program inhibit mode. By confining the GIDL effect to specific localized regions rather than applying it universally across all strings, the energy consumption is minimized while still achieving the desired channel potential stabilization where needed.
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 enhances the electrical characteristics of memory devices by stabilizing channel potential levels, reducing program disturb phenomena, and improving overall program operation reliability.
Implementation Method 1
the control logic controls the operation of the peripheral circuit to generate Gate Induced Drain Leakage (GIDL) at a channel under a source select transistor of each of the plurality of strings during the hole injection operation
Data Source
AI summary
A memory device includes a memory cell array including a plurality of strings, a peripheral circuit coupled to the memory cell array and configured for sequentially performing a program voltage apply operation, a program verify operation, and a hole injection operation on the plurality of strings, and a control logic configured for controlling an operation of the peripheral circuit, wherein the control logic controls the operation of peripheral circuit to generate Gate Induced Drain Leakage (GIDL) at a channel under a select transistor of each of the plurality of strings during the hole injection operation.