Asymmetric Fin FET Source/Drain Structure for Short Channel Effect
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Solution Overview
Problem
The down-scaling of integrated circuit devices leads to a short channel effect, reducing their reliability due to electrical shorts between adjacent source/drain regions as the distance between them decreases.
Innovation Solution
The design incorporates fin active regions with asymmetrically shaped source/drain regions and a gate structure that includes a gate electrode, gate insulating layer, and gate capping layer, with specific materials and epitaxial growth processes to prevent electrical shorts by increasing the separation distance between adjacent source/drain regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between adjacent source/drain regions is reduced to increase integration density, then productivity and integration density are improved, but electrical shorts occur between adjacent source/drain regions reducing reliability
Solution Approach 1:
The source/drain regions are designed with asymmetric cross-sectional shapes rather than symmetric shapes. Specifically, the cross-section perpendicular to the first direction has an asymmetric shape with respect to a center line in the second direction, creating unequal sidewall profiles that prevent direct alignment and electrical contact between adjacent source/drain regions when viewed from the top, thus preventing shorts while maintaining high integration density
Solution Approach 2:
The solution moves the separation mechanism from the planar (top-down) view to the vertical cross-sectional view. By creating asymmetric profiles in the vertical dimension, the patent ensures that adjacent source/drain regions are separated when viewed in cross-section, even though they may appear close or aligned when viewed from the top, thus preventing electrical shorts through a different dimensional approach
2Volume of moving object
If down-scaling is performed to make devices smaller, then device size is reduced improving integration, but short channel effect increases reducing reliability
Solution Approach 1:
The asymmetric cross-sectional shape of source/drain regions creates unequal sidewall profiles that extend differently in the vertical direction. This asymmetry allows for better control of the channel length and reduces the short channel effect by creating a more favorable electric field distribution in the channel, even as device dimensions are scaled down
Data Source
AI summary
An integrated circuit device includes: a first fin active region extending in a first direction parallel to a top surface of a substrate; a second fin active region extending in the first direction and spaced apart from the first fin active region in a second direction different from the first direction; a gate line intersecting the first and second fin active regions; a first source/drain region on one side of the gate line in the first fin active region; and a second source/drain region on one side of the gate line in the second fin active region and facing the first source/drain region, wherein a cross-section of the first source/drain region perpendicular to the first direction has an asymmetric shape with respect to a center line of the first source/drain region in the second direction extending in a third direction perpendicular to the top surface of the substrate.