3D Memory Contact Structure Layout for Void-Free Trench Filling
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Solution Overview
Problem
Planar memory cells face challenges in scaling due to process and fabrication limitations, leading to density constraints and increased costs, while 3D memory architectures offer a solution by enabling higher density but require complex etching processes that can result in voids and material damage.
Innovation Solution
The formation of contact recesses before trenches allows for optimized deposition of conductive materials, minimizing voids and material damage, and simplifying the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to form contact structures in 3D memory devices, then trenches can be formed to enable vertical connections, but voids and material damage occur during the filling process
Solution Approach 1:
The method forms contact recesses in the stack structure before forming the trenches. This preliminary action creates a prepared interface that ensures proper material deposition and prevents void formation during the subsequent trench filling process, thereby maintaining material integrity while achieving precise contact structure formation
Solution Approach 2:
The contact structure formation is divided into distinct segments: first forming contact recesses, then forming trenches, and finally filling with conductive material. This segmentation allows each step to be optimized independently, preventing the void and material damage issues that occur when using conventional single-step etching processes
2Manufacturing precision
If planar process technology is improved to scale memory cells to smaller sizes, then manufacturing precision can be maintained, but fabrication costs increase and density approaches upper limits
Solution Approach 1:
The patent transitions from planar memory cell architecture to three-dimensional vertical architecture. By stacking conductive layers and dielectric layers vertically to form a multi-layer stack structure, the invention achieves higher memory density without requiring further reduction in lateral feature sizes, thereby avoiding the increased fabrication costs associated with extreme planar scaling
3Manufacturing precision
If trenches with width smaller than contact recesses are formed, then even filling is achieved minimizing voids, but additional patterning steps are required
Solution Approach 1:
Contact recesses are formed as a preliminary structure before trench formation. The contact recesses serve as a template that guides the subsequent trench etching process, ensuring that the trenches have the precise width needed for uniform material filling. This preliminary patterning action eliminates the need for additional complex patterning steps while achieving the desired trench dimensions
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 ensures even filling of trenches, reduces fabrication costs, and minimizes the 'F' attack and puddle effect, enhancing the reliability and efficiency of 3D memory devices.
Implementation Method 1
patterning the etch mask and the stack structure via the one or more contact recesses to form one or more trenches
Implementation Method 2
filling each of the one or more trenches with a conductive material to form one or more contact structures
Data Source
AI summary
In certain aspects, a three-dimensional (3D) memory device includes a stack structure including interleaved conductive layers and dielectric layers and having a core array region and a staircase region in a plan view, one or more channel structures each extending through the core array region of the stack structure, and one or more contact structures each extending through the stack structure, wherein each of the one or more contact structures includes a head portion and a body portion, and a width of the head portion of the respective contact structure is larger than that of the body portion of the respective contact structure.