3D Memory Backside Trenches with Doped Bridge Support
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Solution Overview
Problem
Three-dimensional memory devices with backside trenches are prone to deformation or collapse during the replacement of sacrificial material layers with electrically conductive layers, which can lead to structural instability and device failure.
Innovation Solution
Incorporating doped semiconductor bridge structures within the backside trenches to provide structural support and stability during the replacement process, formed by implanting boron into semiconductor trench fill structures and selectively etching the sacrificial material layers while maintaining the doped semiconductor bridges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If backside trenches are used to separate alternating stacks, then device integration density is improved, but structural stability deteriorates during sacrificial material replacement
Solution Approach 1:
A doped semiconductor bridge structure is introduced as an intermediary element within the backside trench to provide mechanical support. The bridge structure comprises a doped semiconductor material that maintains structural integrity during the sacrificial material replacement process, preventing deformation and collapse of the trench while allowing the trench to exist for device integration purposes.
Solution Approach 2:
The backside trench structure is transformed into a composite system by combining the doped semiconductor bridge material with the trench fill material. This composite structure provides both the structural support needed to prevent collapse and the trench configuration needed for device integration, resolving the contradiction between stability and integration density.
2Stability of the object's composition
If doped semiconductor bridge structures are added to backside trenches, then structural stability is improved, but device complexity increases
Solution Approach 1:
The semiconductor material in the bridge structure is doped to alter its electrical and mechanical properties. By changing the doping parameters, the material gains enhanced structural stability while maintaining compatibility with existing semiconductor fabrication processes, thus adding functionality without proportionally increasing complexity.
Solution Approach 2:
The doped semiconductor bridge structures are formed in advance during the fabrication process, before the sacrificial material replacement step. This preliminary action ensures structural support is already in place when needed, preventing deformation during subsequent processing steps and simplifying the overall process control.
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 doped semiconductor bridge structures effectively reduce deformation and enhance the structural integrity of the three-dimensional memory device, ensuring stable operation and reliability by providing support during the conversion of sacrificial layers to conductive layers.
Implementation Method 1
a backside trench fill structure located within the backside trench and comprising at least one bridge structure including a doped semiconductor material
Implementation Method 2
formed by implanting boron into semiconductor trench fill structures
Data Source
AI summary
A vertically alternating sequence of continuous insulating layers and continuous sacrificial material layers is formed over a substrate, and memory opening fill structures including vertical stacks of memory elements are formed through the vertically alternating sequence. Backside trenches are formed to divide the vertically alternating sequence into a plurality of alternating stacks of insulating layers and sacrificial material layers. A set of one or more bridge structures including a doped semiconductor material is formed within each of the backside trenches. The sacrificial material layers are replaced with electrically conductive layers while the sets of at least one bridge structure are present within the backside trenches.