Buried Word Line Isolation Layout for Reduced Cell Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor devices face challenges in improving word line interference between adjacent cells, which affects the reliability and integration of the semiconductor device.
Innovation Solution
A semiconductor device structure is developed with a buried word line and a device isolation layer that includes alternating first and second regions with different intervals, where the second region is formed by a stack structure of insulating layers, reducing word line interference by minimizing the area of the field gate electrode facing the active gate electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform device isolation layer is used to define active regions, then the manufacturing process is simple, but word line interference between adjacent cells increases
Solution Approach 1:
The device isolation layer is segmented into multiple regions with different intervals. Specifically, first regions have a first interval and second regions have a second interval that is larger than the first interval. This segmentation allows different portions of the isolation layer to serve different functions: the first regions provide standard isolation, while the second regions with larger intervals reduce word line interference between adjacent cells.
Solution Approach 2:
Different regions of the device isolation layer are given different local properties through varying the intervals between active regions. The first regions maintain a standard interval for normal device operation, while the second regions are specifically designed with a larger interval to locally reduce capacitive coupling and word line interference in critical areas between adjacent cells.
2Reliability
If the interval between active regions is increased to reduce word line interference, then the reliability improves, but the integration density decreases
Solution Approach 1:
Rather than uniformly increasing the interval between all active regions, the patent segments the device isolation layer into first regions with standard intervals and second regions with enlarged intervals. This allows the interval to be increased only where necessary to reduce word line interference, while maintaining tighter spacing in other areas to preserve overall integration density.
Solution Approach 2:
The interval between active regions is optimized locally rather than globally. Second regions have larger intervals specifically where word line interference is a problem, while first regions maintain smaller intervals to maximize integration density. This local optimization approach addresses interference issues without sacrificing overall device integration.
3Reliability
If a simple single-layer isolation structure is used, then the manufacturing process is easier, but the ability to control word line interference is insufficient
Solution Approach 1:
The device isolation layer is fabricated as a segmented structure with first regions and second regions having different intervals. This segmentation provides the necessary control over word line interference while using standard semiconductor fabrication techniques such as selective epitaxial growth or selective deposition, making the manufacturing process manageable despite the increased structural complexity.
Solution Approach 2:
The isolation layer is formed with different local properties through selective growth or deposition processes. By controlling the growth conditions or deposition parameters in different regions, the patent achieves different interval dimensions in first and second regions, providing precise control over word line interference while using established manufacturing techniques.
Data Source
AI summary
Present invention provides a method of fabricating a semiconductor device capable of improving word line interference between adjacent cells. A semiconductor device comprises: a device isolation layer defining active regions on a substrate and including a first region and a second region, the active regions being spaced apart in a first direction by the first region having a first interval and by the second region having a second interval being larger than the first interval; a gate trench extending in the first direction to cross the active regions and the first and second regions; and a buried word line gap-filling the gate trench, wherein the first region disposed below the gate trench is formed by the first insulating layer, and wherein the second region disposed below the gate trench is formed by a stack structure of the first insulating layer and a second insulating layer.