Trench-Embedded Stacked Structure for 3D Memory Tilting
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Solution Overview
Problem
Three-dimensional non-volatile memory devices face challenges in manufacturing due to the tilting of stacked structures and increased level differences between regions, leading to difficulties in contact plug formation and potential failures.
Innovation Solution
A semiconductor device with a stacked structure formed in a trench, where a first stacked structure includes alternately layered conductive and insulating materials, and a second stacked structure with exposed conductive layers along stepped sidewalls, supporting a semiconductor pillar and reducing contact plug heights, thereby preventing tilting and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are stacked vertically to increase integration density, then storage capacity is improved, but the stacked structure tilts during manufacturing
Solution Approach 1:
The stacked structure is divided into multiple alternating layers of first material layers (e.g., conductive materials like tungsten or polysilicon) and second material layers (e.g., insulating materials like silicon oxide or silicon nitride). This segmentation provides internal structural support that prevents tilting while maintaining vertical stacking for high density.
Solution Approach 2:
The stacked structure uses composite materials with different mechanical properties - conductive layers provide structural rigidity while insulating layers provide support and electrical isolation. This composite construction enhances overall structural stability and prevents tilting during manufacturing processes.
2Quantity of substance
If stacked structures are formed in cell regions, then integration density is improved, but level difference between cell region and peripheral region increases
Solution Approach 1:
The stacked structure is formed locally in the cell region using alternating material layers with different heights and properties. The first material layers extend to different heights than the second material layers, creating a stepped configuration that allows selective contact formation while managing level differences between cell and peripheral regions.
3Ease of manufacture
If level difference between regions is reduced, then contact plug height is improved, but manufacturing complexity increases
Solution Approach 1:
The contact formation process is segmented into multiple steps corresponding to different material layers. First contact plugs are formed through first contact holes to reach first material layers, and second contact plugs are formed through second contact holes to reach second material layers. This segmentation simplifies each individual contact formation step while accommodating the overall complex stacked structure.
Data Source
AI summary
A semiconductor device includes a trench formed in a substrate, a first stacked structure formed in the trench and including a plurality of first material layers and a plurality of second material layers stacked alternately on top of each other, and a transistor located on the substrate at a height corresponding to a top surface of the first stacked structure.