3D Memory Channel Formation After Word Line Replacement
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Solution Overview
Problem
Current methods for forming three-dimensional memory devices face challenges in efficiently creating memory openings and filling structures with vertical semiconductor channels and memory films, particularly in achieving precise and reliable electrical conductivity and structural integrity.
Innovation Solution
The method involves forming an alternating stack of insulating and sacrificial material layers, creating memory openings, replacing sacrificial layers with conductive layers, and forming memory opening fill structures with a metallic fill material and tubular metallic liners, which includes a halogen outgassing process to remove trapped halogen and improve structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sacrificial material layers are replaced with electrically conductive layers after forming memory openings, then electrical conductivity is improved, but structural integrity during processing deteriorates
Solution Approach 1:
The patent applies preliminary action by forming the memory opening fill structure (containing the vertical semiconductor channel and memory film) before replacing the sacrificial material layers with electrically conductive layers. This sequence ensures that the memory structure is established while the sacrificial materials provide structural support, preventing collapse during subsequent processing steps. The sacrificial layers act as temporary structural elements that are removed and replaced only after the memory opening is filled.
2Manufacturing precision
If memory opening fill structure is formed before replacing sacrificial layers, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The patent uses the sacrificial material layers as intermediary structures that facilitate precise formation of the memory opening fill structure. The sacrificial layers serve as temporary templates and structural supports during the formation process, enabling precise alignment of the vertical semiconductor channel and memory film. After the fill structure is formed, the sacrificial layers are removed and replaced with electrically conductive layers, completing the process while maintaining precision.
3Reliability
If metallic fill material with tubular metallic liners is used, then electrical conductivity is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent applies segmentation by dividing the electrically conductive layer into multiple functional components: a metallic fill material layer providing bulk conductivity and tubular metallic liners providing surface conductivity and interface protection. This segmented structure allows each component to be optimized independently - the fill material for volumetric conductivity and the liners for surface quality and adhesion - thereby achieving high electrical conductivity while managing manufacturing complexity through modular deposition processes.
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 enhances the filling of backside recesses with self-aligned tubular metallic liners, reduces resistivity, and minimizes halogen outgassing damage, resulting in improved electrical conductivity and structural reliability of the memory device.
Implementation Method 1
which includes a halogen outgassing process to remove trapped halogen and improve structural integrity
Data Source
AI summary
A method of forming a three-dimensional memory device includes forming an alternating stack of insulating layers and sacrificial material layers over a substrate, forming a memory opening extending through the alternating stack, forming a sacrificial memory opening fill structure in the memory opening, replacing the sacrificial material layers with electrically conductive layers, removing the sacrificial memory opening fill structure selective to the electrically conductive layers, and forming a memory opening fill structure the memory opening after replacing the sacrificial material layers with electrically conductive layers and after removing the sacrificial memory opening fill structure. The memory opening fill structure includes a memory film and a vertical semiconductor channel.