Semiconductor Memory Charge Accumulating Layer Corner Field Control
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Solution Overview
Problem
Concentration of electric fields at corners in semiconductor memory devices can lead to malfunctions, such as reading memory cells as ON states when they should be OFF, due to the formation of unintended electron channels.
Innovation Solution
Incorporating regions with high oxygen concentrations in the charge accumulating layers, such as aluminum oxide or aluminum oxynitride, at the ends of the charge accumulating layers to suppress the effects of fringe electric fields and prevent unintended electron channel formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional charge accumulating layers (silicon nitride or floating gate) are used, then data storage capability is achieved, but electric field concentration at corners causes unintended electron channel formation and read malfunctions
Solution Approach 1:
The charge accumulating layer is divided into regions with different compositions: a first region with aluminum oxide or aluminum oxynitride having high oxygen concentration and negative fixed charges at the corners, and a second region with different composition in the intermediate area. This local differentiation suppresses electric field concentration at corners while maintaining data storage functionality in the intermediate region.
Solution Approach 2:
The charge accumulating layer uses a composite structure combining aluminum oxide and aluminum oxynitride materials with different oxygen concentrations. The first region contains aluminum oxide or aluminum oxynitride with high oxygen concentration to provide negative fixed charges, while the second region has different composition, creating a composite material system that simultaneously addresses electric field control and charge storage.
2Reliability
If uniform charge accumulating layer composition is used, then manufacturing simplicity is maintained, but electric field distribution becomes uneven causing corner effects
Solution Approach 1:
The charge accumulating layer employs local quality variation by creating a first region at the corners with aluminum oxide or aluminum oxynitride containing oxygen at concentrations of 5 at% or more (preferably 10 at% or more, more preferably 20 at% or more) to generate negative fixed charges, while the second region in the intermediate area has different composition. This localized compositional control achieves uniform electric field distribution without requiring complex overall structure changes.
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 effectively prevents the formation of unintended electron channels, ensuring accurate read operations and maintaining the semiconductor memory device's functionality by utilizing materials with negative fixed charges to counteract the electric field concentration at corners.
Implementation Method 1
utilizing materials with negative fixed charges to counteract the electric field concentration at corners
Data Source
AI summary
A semiconductor memory device includes: a first and a second electrodes aligned in a first direction; a first semiconductor layer provided between the first and the second electrodes; a second semiconductor layer provided between the first semiconductor layer and the second electrode; a first charge accumulating layer provided between the first electrode and the first semiconductor layer; and a second charge accumulating layer provided between the second electrode and the second semiconductor layer. At least one of the first and the second charge accumulating layers include: a first and a second regions including nitrogen, aluminum, and oxygen and having different positions in a second direction; and a third region provided between the first and the second regions in the second direction. Oxygen is not included in the third region or a concentration of oxygen in the third region is lower than that in the first and the second regions.