3D Memory Barrier Films Block Fluorine Diffusion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fluorine diffusion between word lines and insulating layers in three-dimensional memory devices can lead to reliability issues, such as void formation and electrical shorts, due to the adverse impact on the insulating layers and material migration.
Innovation Solution
A method involving the use of a barrier layer stack, specifically a combination of a polycrystalline titanium nitride (TiN) layer and a tungsten layer, where the TiN layer is oxidized to form an amorphous titanium oxide or oxynitride layer, effectively blocking fluorine diffusion and enhancing the structural integrity of the memory device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorine-containing materials are used in word lines, then electrical conductivity is improved, but fluorine diffusion causes void formation and electrical shorts in insulating layers
Solution Approach 1:
A titanium nitride barrier layer is introduced as an intermediary between the fluorine-containing word line material and the insulating layers. This barrier layer effectively blocks fluorine diffusion while allowing the device to maintain electrical conductivity and structural integrity.
Solution Approach 2:
The patent uses a composite structure combining titanium nitride barrier layer with fluorine-containing conductive material (such as tungsten deposited from WF6). This composite approach allows the device to benefit from both the fluorine-containing material's electrical properties and the titanium nitride's diffusion-blocking properties.
2Reliability
If barrier layers are added to block fluorine diffusion, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent optimizes the thickness of the titanium nitride barrier layer to a specific range (1-10 nm) to achieve effective fluorine blocking while minimizing the increase in device complexity. By carefully controlling this parameter, the barrier function is achieved with minimal additional structural complexity.
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 significantly reduces fluorine diffusion, minimizes damage to adjacent layers, and improves the electrical conductivity and structural stability of the memory device, leading to enhanced reliability and performance.
Implementation Method 1
the TiN layer is oxidized to form an amorphous titanium oxide or oxynitride layer
Implementation Method 2
effectively blocking fluorine diffusion
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Memory stack structures are formed through an alternating stack of insulating layers and sacrificial material layers. Backside recesses are formed by removal of the sacrificial material layers selective to the insulating layers and the memory stack structures. A barrier layer stack including a crystalline electrically conductive barrier layer and an amorphous barrier layer is formed in the backside recesses prior to formation of a metal fill material layer.