Source/Drain Isolation Structure for Epitaxial Merge Prevention
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Solution Overview
Problem
As semiconductor devices continue to shrink, adjacent transistors' epitaxial source/drain features merge, leading to electrical shorting and performance degradation or device failures due to insufficient spacing and process variations.
Innovation Solution
Implementing isolation structures between source/drain components using etching-stop layers, material layers, and patterning processes to separate merged source/drain features, followed by deposition of isolation structures to prevent electrical bridging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device geometry is scaled down to increase functional density, then productivity and production efficiency are improved, but manufacturing precision deteriorates due to insufficient spacing between adjacent transistors causing epitaxial source/drain merging
Solution Approach 1:
The patent divides the merged source/drain structure into separate regions by forming isolation structures (trenches filled with dielectric material) between adjacent transistors. This segmentation physically separates the epitaxial source/drain regions that would otherwise merge during scaling, allowing continued miniaturization while maintaining electrical isolation and manufacturing precision.
2Area of stationary object
If spacing between adjacent transistors is reduced to increase functional density, then area utilization is improved, but reliability deteriorates due to electrical shorting between merged source/drain features
Solution Approach 1:
The patent introduces isolation structures as intermediary elements between adjacent source/drain regions. These isolation structures (comprising trenches filled with dielectric material) act as mediators that prevent direct electrical contact between merged source/drain features, thereby maintaining electrical isolation and reliability even when transistors are placed in close proximity for high density.
3Device complexity
If conventional fabrication methods are used without additional isolation structures, then device complexity is reduced, but manufacturing precision deteriorates due to inability to prevent epitaxial merging
Solution Approach 1:
The patent performs preliminary actions by forming isolation structures before completing the source/drain formation process. The trenches are etched and filled with dielectric material in advance, creating physical barriers that guide the subsequent epitaxial growth and prevent merging. This preliminary structuring enables precise source/drain separation without requiring complex real-time control during epitaxial processing.
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
Prevents electrical shorting between transistors, improving device yield and performance by ensuring physical and electrical separation of source/drain components.
Implementation Method 1
an isolation structure is disposed between the first source/drain structure and the second source/drain structure
Implementation Method 2
epitaxial source/drain features between adjacent transistors to merge into one another
Data Source
AI summary
A first source/drain structure is disposed over a substrate. A second source/drain structure is disposed over the substrate. An isolation structure is disposed between the first source/drain structure and the second source/drain structure. The first source/drain structure and a first sidewall of the isolation structure form a first interface that is substantially linear. The second source/drain structure and a second sidewall of the isolation structure form a second interface that is substantially linear. A first source/drain contact surrounds the first source/drain structure in multiple directions. A second source/drain contact surrounds the second source/drain structure in multiple directions. The isolation structure is disposed between the first source/drain contact and the second source/drain contact.