Curved Floating Gate Electrode for Semiconductor Memory
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Solution Overview
Problem
Conventional semiconductor memory devices face challenges in increasing capacity beyond miniaturization limits, particularly in ensuring reliability in stacked-type designs where interconnects and semiconductor members intersect, leading to potential electrical field concentration and tunneling insulating film deterioration.
Innovation Solution
The semiconductor memory device incorporates a floating gate electrode with a semi-circular shape and a curvature radius that is larger at the corner facing the semiconductor member than at the corner facing the interconnect, preventing electric field concentration and using a tunneling insulating film and block insulating film to stabilize electron storage and improve data holding characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a stacked-type semiconductor memory device is used to increase capacity beyond miniaturization limits, then storage capacity is improved, but electric field concentration occurs at corner portions of the floating gate electrode, leading to tunneling insulating film deterioration and reduced reliability
Solution Approach 1:
The floating gate electrode is designed with a curved lateral surface instead of sharp corners. The corner portions facing the semiconductor member are formed with a curvature radius larger than other portions, which prevents electric field concentration and reduces deterioration of the tunneling insulating film during write and erase operations.
Solution Approach 2:
Different portions of the floating gate electrode have different curvature radii. The corner portions facing the semiconductor member have a larger curvature radius to prevent electric field concentration, while other portions have smaller curvature radii. This local differentiation optimizes both storage capacity and reliability.
2Quantity of substance
If the floating gate electrode has sharp corners to maximize electron storage, then storage capacity is improved, but electric field concentration occurs causing tunneling insulating film breakdown
Solution Approach 1:
The floating gate electrode is designed with a curved lateral surface instead of sharp corners. The corner portions facing the semiconductor member are formed with a curvature radius larger than other portions, which prevents electric field concentration and reduces deterioration of the tunneling insulating film during write and erase operations.
Solution Approach 2:
The curvature radius of the floating gate electrode's corner portions is specifically controlled to be larger than other portions. This parameter change in the geometric shape prevents electric field concentration while maintaining adequate electron storage capacity.
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 design enhances electron storage capacity, operational margin, and data holding characteristics while maintaining high reliability by preventing electric field concentration and reducing tunneling insulating film deterioration during writing and erasing operations.
Implementation Method 1
A curvature radius of a corner portion facing the semiconductor member in the first electrode is larger than a curvature radius of a corner portion facing the first interconnect in the first electrode
Data Source
AI summary
A semiconductor memory device includes a semiconductor member extending in a first direction, a first interconnect extending in a second direction crossing the first direction, and a first electrode disposed between the semiconductor member and the first interconnect. A curvature radius of a corner portion facing the semiconductor member in the first electrode is larger than a curvature radius of a corner portion facing the first interconnect in the first electrode.