Suspended Gate Non-Volatile Memory for Data Retention
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Solution Overview
Problem
Standard non-volatile memories, such as flash memory, face data retention issues due to charge loss from floating gates caused by tunnel oxide leakage, detrapping, and mobile ions, leading to a need for improved data retention mechanisms.
Innovation Solution
A suspended gate non-volatile memory design where a carrier storage node is normally separated from the substrate by a tunnel oxide, with a movable suspended structure that contacts the tunnel oxide during operations, suppressing leakage current and enhancing data retention through a metal gate suspended over a substrate by supporting arms, controlled by pull-in/pull-out voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a floating gate structure is used in standard non-volatile memory, then data storage capability is achieved, but charge loss occurs due to tunnel oxide leakage, detrapping, and mobile ions
Solution Approach 1:
The patent extracts the floating gate from direct contact with the tunnel oxide by introducing a suspended structure with supporting arms. The gate is physically separated from the substrate, removing it from the harmful environment that causes charge loss while maintaining its data storage function.
Solution Approach 2:
The patent introduces an intermediary suspended structure consisting of supporting arms that hold the gate away from the tunnel oxide. This intermediary structure acts as a mediator, allowing the gate to maintain its function while being isolated from the sources of charge loss.
2Reliability
If a suspended gate structure is used to reduce leakage current, then data retention is improved, but device complexity increases due to supporting arms and movable structure
Solution Approach 1:
The patent employs a dynamic suspended gate structure that can move between different positions. The gate is supported by elastic arms that allow controlled movement, enabling the structure to adapt its position based on operational requirements while maintaining simplicity through the use of elastic mechanical elements.
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
The suspended gate structure improves data retention by minimizing leakage current and reducing floating gate coupling, enabling high-performance operation with reduced parasitic capacitance and floating gate interference, thus enhancing the overall performance of memory cells and arrays.
Implementation Method 1
contacting the tunnel oxide suppresses leakage current through the tunnel oxide
Implementation Method 2
Pull-in voltage on a pull-in/pull-out gate causes the suspended structure to deflect toward the substrate, and pull-out voltage on the pull-in/pull-out gate causes the suspended structure to deflect away from the substrate
Data Source
AI summary
A carrier storage node such as a floating gate is formed on a moving electrode with a control gate to form a suspended gate non-volatile memory, reducing floating gate to floating gate coupling and leakage current, and increasing data retention.