Memory Cell Trench Contact Layout for 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 due to the need for precise control of gate electrodes.
Innovation Solution
The semiconductor memory device incorporates a unique structure with multiple trenches and device isolation layers, along with direct and buried contacts, and fins, to enhance the reliability of gate electrode control. This structure includes first and second trenches with different widths and depths, and device isolation layers made of silicon oxide or silicon nitride, which are tapered to ensure effective isolation and contact formation.
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 the manufacturing process increases
Solution Approach 1:
The substrate is divided into multiple trenches (first trenches and second trenches) with different widths and depths, creating segmented isolation regions. This segmentation allows for differentiated control of gate electrodes and conductive patterns in different areas, managing manufacturing complexity through structured division while maintaining high integration density.
Solution Approach 2:
Different regions of the substrate are given different properties through the trench structure - first trenches have greater width and depth than second trenches, creating local variations in isolation characteristics. This local quality differentiation enables precise control of electrical properties and mechanical stress in specific areas, facilitating reliable connections in high-density integration.
2Reliability
If multiple trenches with different widths and depths are formed, then the isolation effectiveness is improved, but the manufacturing precision requirements increase
Solution Approach 1:
Device isolation layers are formed in the trenches before active region formation and contact fabrication. This preliminary isolation structure establishes the foundational geometry and electrical separation early in the manufacturing process, providing a stable reference framework that guides subsequent processing steps and reduces cumulative precision errors.
Solution Approach 2:
The first trenches and second trenches are designed with asymmetric dimensions - different widths and depths - to create distinct isolation characteristics for different functional regions. This asymmetric design optimizes electrical isolation and mechanical stress distribution while the structured asymmetry provides clear process control parameters that simplify manufacturing precision management.
3Reliability
If direct contacts and buried contacts are formed at different heights, then the gate electrode control is improved, but the device structure complexity increases
Solution Approach 1:
The contact structure utilizes vertical dimensionality by forming direct contacts and buried contacts at different height levels within the trench structure. This multi-level vertical arrangement enables independent electrical connections to different regions of the active areas, providing enhanced gate electrode control and electrical isolation without requiring additional lateral space, thus managing structural complexity through vertical stratification.
Data Source
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Figure 2A
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.