3D Memory Cell Contact Alignment for Dense Vertical Transistors
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Solution Overview
Problem
Planar memory cells face density limitations and fabrication challenges as feature sizes approach a lower limit, leading to increased costs and complexity in scaling.
Innovation Solution
Implementing a 3D memory architecture with vertical transistors and a hard mask for self-alignment during trench formation, using low-leakage materials like metal oxide semiconductor for channel layers and simplifying the source node contact process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If planar memory cells are scaled to smaller sizes by improving process technology and fabrication process, then memory density is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent transitions from planar (2D) memory cell architecture to three-dimensional (3D) memory architecture. The memory stack includes vertically stacked components such as bit lines, word lines, and memory cells arranged in multiple layers, enabling increased storage density without proportionally increasing fabrication complexity. This dimensional transition allows continued scaling while maintaining process feasibility.
2Quantity of substance
If feature sizes of memory cells approach a lower limit, then memory density approaches upper limit, but planar process and fabrication techniques become challenging and costly
Solution Approach 1:
The patent employs a three-dimensional memory architecture with vertically stacked memory cells, bit lines, and word lines. This stack-based design enables continued memory density improvement by adding vertical layers rather than reducing lateral feature sizes, thereby avoiding the fabrication challenges and costs associated with extreme miniaturization of planar structures.
3Quantity of substance
If 3D memory architecture is implemented to address density limitation, then memory density is improved, but device structure complexity increases
Solution Approach 1:
The 3D memory architecture is segmented into distinct functional layers including bit line structures, word line structures, and memory cell regions arranged in a stack. Each layer performs a specific function and can be independently optimized. The bit lines extend in a first direction while word lines extend in a second direction perpendicular to the first, creating a modular structure that manages complexity through functional segmentation.
Solution Approach 2:
The gate structures in the 3D memory architecture serve multiple functions: they act as control electrodes for memory cell operation, provide structural support for the vertical stack, and enable routing connections between different memory layers. This multi-functionality reduces the need for separate dedicated structures, thereby managing overall device complexity while maintaining high density.
Data Source
AI summary
A semiconductor device includes a first gate structure and a second gate structure extending in a first direction and a second direction, a first isolation structure deposited between the first gate structure and the second gate structure extending in the first direction and the second direction, a first semiconductor structure deposited between the first gate structure and the first isolation structure extending in the first direction, a first contact structure deposited on the first semiconductor structure, a first dielectric layer deposited on the first gate structure, and a second dielectric layer deposited on the first isolation structure. A first center of the first end of the first contact structure in a third direction is perpendicular to the first direction. The second direction aligns with a second center of the first semiconductor structure in the third direction.