3D Memory Conductive Layers with Molybdenum Liners
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently integrating molybdenum-containing conductive liners and metal fill portions to enhance memory stack structures, particularly in achieving optimal threshold voltage control and programming efficiency.
Innovation Solution
A three-dimensional memory device is designed with an alternating stack of insulating and electrically conductive layers, where each conductive layer comprises a molybdenum-containing conductive liner directly on a blocking dielectric layer and a metal fill portion made of a different metal, such as tungsten, to form memory stack structures with vertical semiconductor channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a molybdenum-containing conductive liner is used directly on the blocking dielectric layer, then threshold voltage control and programming efficiency are improved, but the cost increases due to expensive molybdenum-containing precursor gases
Solution Approach 1:
The conductive liner is segmented into two distinct layers: a molybdenum-containing liner layer (first conductive material) and a metal fill layer (second conductive material). This segmentation allows the expensive molybdenum layer to be limited to a thin barrier layer, while the bulk conductivity is provided by the cheaper metal fill, thus reducing overall cost while maintaining threshold voltage control functionality.
Solution Approach 2:
The molybdenum-containing liner layer acts as an intermediary between the blocking dielectric layer and the metal fill layer. It provides the necessary diffusion barrier and interface quality for optimal threshold voltage control, while the metal fill layer serves as the bulk conductive material, separating the conflicting requirements of interface quality and cost efficiency.
2Reliability
If a molybdenum-containing conductive liner is used directly on the blocking dielectric layer, then programming efficiency is improved, but the manufacturing complexity increases
Solution Approach 1:
The conductive liner formation process is segmented into two sequential steps: first depositing the molybdenum-containing liner layer, then filling with metal. This segmentation transforms a complex single-step process into two simpler, more controllable steps, each optimized for its specific material and function.
Solution Approach 2:
The molybdenum-containing liner layer is formed in advance as a preliminary step before metal fill deposition. This preliminary action prepares the interface with optimal properties for subsequent metal filling, ensuring programming efficiency while simplifying the overall process through clear sequential steps.
3Reliability
If the conductive liner is formed directly on the blocking dielectric layer, then diffusion barrier properties are improved, but material usage efficiency decreases
Solution Approach 1:
The molybdenum-containing material is applied with local quality differentiation: a thin liner layer (0.5-5 nm) provides the diffusion barrier at the critical interface, while the bulk volume is occupied by cheaper metal fill material. This local quality optimization minimizes expensive molybdenum usage while maintaining diffusion barrier functionality.
Solution Approach 2:
The conductive liner is formed as a composite structure combining molybdenum-containing material and metal fill material. This composite approach leverages the superior diffusion barrier properties of molybdenum at the interface while using abundant, cost-effective metal materials for the bulk conductive function, optimizing both performance and material efficiency.
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 configuration improves the threshold voltage control and programming efficiency by providing a diffusion barrier and reducing resistivity, while minimizing the use of expensive molybdenum-containing precursor gases, thus enhancing the overall performance and cost-effectiveness of the memory device.
Implementation Method 1
The molybdenum-containing conductive liner is located directly on a blocking dielectric layer
Implementation Method 2
providing a diffusion barrier and reducing resistivity
Data Source
AI summary
An alternating stack of insulating layers and sacrificial material layers is formed over a substrate. Memory stack structures are formed through the alternating stack. Each of the memory stack structures includes a memory film and a vertical semiconductor channel. Backside recesses are formed by removing the sacrificial material layers selective to the insulating layers and the memory stack structures. Electrically conductive layers are formed in the backside recesses. Each of the electrically conductive layers includes a molybdenum-containing conductive liner and a metal fill portion including a metal other than molybdenum.