3D Memory Stack Insulation Structure for Hydrogen Diffusion Control
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Solution Overview
Problem
Current semiconductor memory devices face challenges in maintaining reliable insulation layers and precise control over the thickness of these layers, which can lead to defects and reduced reliability in memory cell arrays due to processing variations and hydrogen diffusion issues.
Innovation Solution
The implementation of a stacked body structure with alternating insulation and conductive layers, where silicon nitride and silicon oxide layers are used to form slits and contacts, with silicon nitride serving as an etching stopper to control layer thickness and terminate dangling bonds, enhancing insulation and contact formation precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional insulation layers are used in NAND flash memory, then manufacturing is simpler, but insulation reliability deteriorates due to processing variations and hydrogen diffusion
Solution Approach 1:
The patent applies composite materials by stacking multiple insulation layers with different material compositions (first insulation layer with silicon nitride, second insulation layer with silicon oxide) to achieve superior insulation reliability. This composite structure compensates for processing variations and prevents hydrogen diffusion better than conventional single-material insulation layers.
Solution Approach 2:
The insulation structure is segmented into multiple distinct layers with different functions - the first insulation layer provides primary insulation and etching stopper functionality, while the second insulation layer provides additional insulation and hydrogen barrier properties. This segmentation allows each layer to be optimized for its specific function, improving overall reliability.
2Manufacturing precision
If conventional single-layer insulation is used, then manufacturing precision is easier to control, but insulation layer thickness precision deteriorates due to processing variations
Solution Approach 1:
By using composite insulation layers with different material properties, the patent achieves better thickness precision. The first insulation layer (silicon nitride) has different etching rates and deposition characteristics than the second insulation layer (silicon oxide), allowing each layer to be independently optimized for thickness control despite processing variations.
Solution Approach 2:
The patent changes material parameters by selecting insulation layers with different compositions and properties. This allows independent optimization of deposition conditions for each layer, improving thickness precision by compensating for processing variations through material selection rather than relying solely on process control.
3Reliability
If conventional insulation structures are used, then device structure is simpler, but hydrogen diffusion control deteriorates leading to memory cell defects
Solution Approach 1:
The composite insulation structure uses silicon nitride in the first layer and silicon oxide in the second layer, creating a multi-functional barrier against hydrogen diffusion. This composite approach provides superior hydrogen blocking capability compared to conventional single-layer structures, preventing memory cell defects while maintaining structural integrity.
Solution Approach 2:
The stacked insulation layers act as intermediary barriers between the memory cell structures and the external environment. The first insulation layer serves as an immediate barrier, while the second insulation layer provides an additional protective layer, collectively preventing hydrogen diffusion that would otherwise reach and damage memory cells.
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 improves the reliability of semiconductor memory devices by maintaining precise insulation layer thickness and reducing defects, while also effectively managing hydrogen diffusion to enhance memory cell performance.
Implementation Method 1
silicon nitride serving as an etching stopper to control layer thickness
Implementation Method 2
silicon nitride serving as an etching stopper to control layer thickness and terminate dangling bonds
Implementation Method 3
effectively managing hydrogen diffusion to enhance memory cell performance
Data Source
AI summary
According to one embodiment, a semiconductor memory device includes a stacked body, memory pillars, first and second insulation layers and an isolation region. The stacked body above a substrate includes conductive layers isolated from each other and stacked along a first direction crossing the substrate surface. The memory pillars extend through the stacked body along the first direction. The first insulation layer is provided above the memory pillars. The isolation region is provided higher than upper surfaces of the memory pillars in the stacked body along the first direction, and isolates the stacked body in a second direction crossing the first direction. The second insulation layer is provided on the first insulation layer and a side wall of the isolation region.