Memory Guard Ring Layout to Limit Dislocation Line Extension
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Solution Overview
Problem
Semiconductor memory devices face reliability issues due to crystal defects originating from the guard ring, which can lead to electrical interference and device malfunctioning.
Innovation Solution
The semiconductor memory device incorporates a branch interconnection in the gate electrode of dummy transistors to intentionally create a stress concentration point, relaxing distortion in the guard ring line and reducing the extension of dislocation lines, thereby minimizing crystal defects and maintaining device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guard ring surrounds an element formation region, then electrical isolation and device protection are improved, but crystal defects and dislocation lines originate from the guard ring, worsening device reliability
Solution Approach 1:
An element isolation region is introduced as an intermediary structure between the circuit region and the guard ring. This isolation region acts as a buffer that prevents direct interaction between the guard ring and the circuit region, thereby blocking the propagation of dislocation lines and crystal defects from the guard ring to the functional circuit elements while maintaining the electrical isolation function of the guard ring.
Solution Approach 2:
The structure is segmented by dividing the space between the circuit region and guard ring into a separate element isolation region. This segmentation creates distinct functional zones: the circuit region for device operation, the element isolation region for defect buffering, and the guard ring for electrical isolation. The segmentation allows the guard ring to fulfill its protective function without directly generating harmful crystal defects in the circuit region.
2Reliability
If a guard ring is used for electrical isolation, then device protection is improved, but distortion in the guard ring line extends to critical regions, worsening device reliability
Solution Approach 1:
The element isolation region serves as a mediator that absorbs and isolates the distortion generated in the guard ring. By placing this isolation region between the guard ring and the circuit region, the distortion in the guard ring line is prevented from extending to critical regions, thereby maintaining the structural stability of the circuit region while preserving the guard ring's electrical isolation function.
Solution Approach 2:
The harmful distortion effect is extracted and contained within the element isolation region. The isolation region effectively separates the distortion source (guard ring) from the sensitive area (circuit region), allowing the guard ring to maintain its protective function while its negative effects (distortion extension) are confined to a non-critical area.
3Reliability
If dummy transistors are added with branch interconnections, then stress concentration points are created to reduce dislocation extension, but device complexity increases
Solution Approach 1:
The gate electrode structure of dummy transistors is modified locally by adding branch interconnections at specific positions. This local modification creates stress concentration points that effectively reduce dislocation extension without requiring a complete redesign of the entire device structure. The branch interconnections are strategically placed to generate the necessary stress distribution, maintaining simplicity while achieving the reliability improvement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the extension of dislocation lines to critical regions, enhancing the reliability of the semiconductor memory device by mitigating distortion and preventing device malfunctioning.
Implementation Method 1
incorporates a branch interconnection in the gate electrode of dummy transistors to intentionally create a stress concentration point, relaxing distortion in the guard ring line and reducing the extension of dislocation lines
Data Source
AI summary
A semiconductor memory device includes: a semiconductor substrate having a surface extending in an X direction and a Y direction; a circuit region formed on the semiconductor substrate and having at least one side extending in the Y direction; a guard ring line extending along the Y direction and opposed to the one side of the circuit region in the X direction; an element isolation region extending along the Y direction and formed between the one side of the circuit region and the guard ring line; and a dummy transistor disposed on an upper surface of the element isolation region. The dummy transistor includes: a main interconnection extending in the Y direction; and a branch interconnection extending from the main interconnection in the X direction.