Memory Cell Trench Layout for Reliable Gate Electrode Control
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Solution Overview
Problem
As semiconductor devices become more integrated, ensuring reliable connection between conductive patterns in semiconductor memory devices has become increasingly complex, particularly in maintaining effective control of gate electrodes.
Innovation Solution
The semiconductor memory device incorporates a design with multiple trenches and device isolation layers in a substrate, featuring direct and buried contacts, and fins, where the widths and depths of the trenches vary, and the device isolation layers have a tapered shape, enhancing control over the gate electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the degree of integration of semiconductor devices is increased, then the size of electronic devices is reduced, but the complexity of manufacturing process increases
Solution Approach 1:
The substrate is divided into multiple regions with different trench configurations. First trenches are formed in first regions while second trenches are formed in second regions, allowing different manufacturing approaches in different areas to optimize both integration density and manufacturing complexity
Solution Approach 2:
Different trench width and depth configurations are applied to different regions of the substrate. The first trenches have different dimensions than the second trenches, enabling local optimization of device performance and manufacturing ease in specific areas
2Reliability
If multiple trenches with different widths and depths are formed, then the control of gate electrode is improved, but the device structure becomes more complex
Solution Approach 1:
The trench structure is segmented into first trenches and second trenches with different dimensions, each serving specific functional requirements. This segmentation allows independent optimization of gate control characteristics without requiring a completely complex unified structure
Solution Approach 2:
The width and depth parameters of trenches are varied between first and second trenches to achieve different electrical characteristics. By changing these geometric parameters, the gate electrode control is optimized while maintaining a manageable structural complexity
3Reliability
If device isolation layers are formed in all trenches, then the electrical isolation is improved, but the manufacturing process becomes more complex
Solution Approach 1:
Device isolation layers are selectively formed only in second trenches, while first trenches rely on substrate isolation or other isolation mechanisms. This segmented approach to isolation provides sufficient electrical isolation without requiring uniform isolation layer formation in all trenches, thereby simplifying the manufacturing process
Data Source
AI summary
Provided is a semiconductor memory device. The semiconductor memory device includes a plurality of trenches including a plurality of first trenches in a substrate and a plurality of second trenches between ones of the plurality of first trenches, and a plurality of device isolation layers. A first height of a lowermost surface of a direct contact in a vertical direction may be higher than a second height of a lowermost surface of a buried contact in the vertical direction, relative to a lower surface of the substrate.