3D Memory Charge Trapping Segmentation and Nesting
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently forming monolithic NAND strings with effective charge trapping and retention, particularly in the integration of alternating insulating and conductive layers and the use of silicon nitride and oxygen-containing dielectric materials for charge storage.
Innovation Solution
A method for forming a three-dimensional memory device with a stack structure comprising alternating insulating and conductive layers, where charge trapping material portions made of silicon nitride and oxygen-containing dielectric compounds are integrated, enabling efficient charge storage and retention by modulating nitrogen concentration for enhanced trapping capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a monolithic NAND string structure with alternating insulating and conductive layers is formed, then device integration density is improved, but manufacturing complexity increases
Solution Approach 1:
The charge storage layer is segmented into vertically isolated portions at different levels, with insulating material separating adjacent charge storage regions. This segmentation enables independent charge trapping at each level while maintaining manufacturing feasibility through modular layer formation.
Solution Approach 2:
The patent implements a nested structure where charge storage layers are positioned within alternating insulating and conductive layers. The tunneling dielectric layer surrounds the semiconductor channel, and charge storage material is positioned adjacent to the tunneling dielectric, creating concentric nested layers that maximize space utilization.
2Reliability
If silicon nitride and oxygen-containing dielectric materials are used for charge storage, then charge trapping capability is improved, but material integration difficulty increases
Solution Approach 1:
Different materials are used at different locations within the charge storage layer. Silicon nitride is positioned at specific vertical levels where high charge trapping is required, while oxygen-containing dielectric materials are used in other regions. This local material optimization achieves superior charge trapping while managing manufacturing complexity through selective material deposition.
Solution Approach 2:
The charge storage layer is formed as a composite structure combining silicon nitride and oxygen-containing dielectric materials. This composite approach leverages the high charge trapping capability of silicon nitride while using oxygen-containing dielectrics for structural stability and interface quality, achieving reliable charge storage with manageable manufacturing processes.
3Duration of action of stationary object
If vertically isolated charge storage regions are formed, then charge retention is improved, but process steps increase
Solution Approach 1:
The alternating stack of insulating and conductive layers is formed prior to creating the memory stack structure. This preliminary formation of the layered stack with pre-positioned insulating material enables subsequent selective removal and charge storage layer formation without requiring additional complex process steps, achieving vertically isolated charge storage regions efficiently.
Solution Approach 2:
Sacrificial insulating material is temporarily incorporated into the alternating stack during preliminary formation, then selectively removed after the memory stack structure is formed. This extraction approach enables the creation of vertically isolated charge storage regions with proper spacing without requiring direct deposition of complex multi-layer structures.
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 solution enhances charge trapping and retention characteristics, improving the performance and reliability of three-dimensional NAND memory devices by utilizing compositionally modulated charge storage layers with silicon nitride and oxygen-containing dielectric materials.
Implementation Method 1
charge trapping material portions made of silicon nitride and oxygen-containing dielectric compounds are integrated, enabling efficient charge storage and retention
Implementation Method 2
enhances charge trapping and retention characteristics, improving the performance and reliability of three-dimensional NAND memory devices by utilizing compositionally modulated charge storage layers
Data Source
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AI summary
A memory opening can be formed through an alternating stack of insulating layers and sacrificial material layers provided over a substrate. Annular etch stop material portions are provided at each level of the sacrificial material layers around the memory opening. The annular etch stop material portions can be formed by conversion of surface portions of the sacrificial material layers into dielectric material portion, or by recessing the sacrificial material layers around the memory opening and filling indentations around the memory opening. After formation of a memory stack structure, the sacrificial material layers are removed from the backside. The annular etch stop material portions are at least partially converted to form charge trapping material portions. Vertical isolation of the charge trapping material portions among one another around the memory stack structure minimizes leakage between the charge trapping material portions located at different word line levels.