Amorphous Barrier Layer for 3D Memory Fluorine Diffusion
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Solution Overview
Problem
Fluorine diffusion between word lines and insulating layers in three-dimensional memory devices can lead to void formation, material migration, and electrical shorts, compromising the reliability of these devices.
Innovation Solution
Incorporating an amorphous electrically conductive barrier layer, such as titanium oxide or titanium oxynitride, between the metal fill material and insulating layers to prevent fluorine diffusion, combined with a metal fill material like tungsten, which is deposited using a fluorine-containing precursor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal fill material layer is deposited using a fluorine-containing precursor, then the metal fill material achieves low resistivity and good electrical conductivity, but fluorine diffusion occurs into insulating layers causing voids, material migration, and electrical shorts
Solution Approach 1:
An amorphous barrier layer is introduced as an intermediary between the metal fill material layer and the insulating layers. This barrier layer selectively blocks fluorine diffusion from the metal fill material into the insulating layers while maintaining electrical conductivity. The amorphous structure of the barrier layer provides a dense, grain-boundary-free path that prevents fluorine migration, thereby resolving the contradiction between achieving low resistivity through fluorine-containing precursors and preventing harmful fluorine diffusion.
Solution Approach 2:
The invention uses a composite structure consisting of the metal fill material layer combined with the amorphous barrier layer. The composite material system leverages the electrical conductivity of the metal fill material while the amorphous barrier layer component provides fluorine diffusion blocking. This composite approach allows simultaneous achievement of low resistivity and prevention of fluorine-induced reliability issues.
2Object-affected harmful factors
If crystalline barrier layers are used to prevent fluorine diffusion, then fluorine blocking is achieved, but grain boundaries in the crystalline structure facilitate fluorine migration and reduce barrier effectiveness
Solution Approach 1:
The invention changes the structural parameter of the barrier layer from crystalline to amorphous. This parameter change eliminates grain boundaries, which are present in crystalline structures and serve as diffusion pathways for fluorine. The amorphous structure provides a more uniform, dense matrix that effectively blocks fluorine migration, thereby improving barrier effectiveness and preventing fluorine-induced reliability issues.
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 amorphous barrier layer effectively suppresses fluorine diffusion, enhancing the reliability and performance of three-dimensional memory devices by reducing grain boundaries and minimizing the risk of electrical shorts, while maintaining low resistivity and large grain sizes for the metal fill material.
Implementation Method 1
An electrically conductive amorphous barrier layer is formed in the backside recesses. A metal fill material layer is formed within remaining volumes of the backside recesses. The amorphous barrier layer effectively suppresses fluorine diffusion
Data Source
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. An electrically conductive, amorphous barrier layer can be formed prior to formation of a metal fill material layer to provide a diffusion barrier that reduces fluorine diffusion between the metal fill material layer and memory films of memory stack structures. The electrically conductive, amorphous barrier layer can be an oxygen-containing titanium compound or a ternary transition metal nitride.