Active Fin Buffer Structure for Leakage Control in FinFETs
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Solution Overview
Problem
In the fabrication of finFETs, the active fin's width increase from top to bottom leads to current concentration at the upper portion and leakage currents at the lower portion, exacerbated by the scaling down of the fin, which increases leakage currents.
Innovation Solution
An active pattern structure is developed with a lower active pattern protruding vertically from the substrate, a buffer structure including aluminum silicon oxide or silicon doped with aluminum, and an upper active pattern with a width increasing from the top to the bottom, where the buffer's minimum width is equal to or less than the upper active pattern's width, reducing the contact area and thus leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the active fin width increases from top to bottom due to patterning process characteristics, then the upper portion current concentration is improved, but leakage currents increase in the lower portion
Solution Approach 1:
The active fin is segmented into two distinct portions: a lower active fin portion and an upper active fin portion. The lower portion has a first width while the upper portion has a second width that is narrower than the first width. This segmentation allows different regions to serve different functions - the wider lower portion provides structural support and reduces leakage, while the narrower upper portion concentrates current for effective operation.
Solution Approach 2:
Different width characteristics are applied to different portions of the active fin structure. The lower active fin portion has a larger width optimized for reducing leakage currents and providing mechanical stability, while the upper active fin portion has a smaller width optimized for current concentration and active device performance. This local quality variation resolves the contradiction between current concentration and leakage prevention.
2Length of moving object
If the active fin is scaled down to improve device miniaturization, then device size is reduced, but leakage currents increase in the lower portion
Solution Approach 1:
By segmenting the active fin into lower and upper portions with different widths, the invention allows the overall fin size to be scaled down while maintaining an optimized width profile. The lower portion can be sufficiently wide to prevent leakage even in scaled-down devices, while the upper portion is appropriately sized for the scaled device dimensions, thus maintaining current concentration effectiveness.
Solution Approach 2:
The width parameter of the active fin is changed along its vertical extent, creating a gradient structure. This parameter variation allows the fin to maintain optimal electrical characteristics across different scale dimensions, preventing leakage currents from increasing as devices are scaled down.
3Object-generated harmful factors
If the contact area between lower and upper active patterns is reduced to minimize leakage currents, then leakage currents decrease, but the structural stability may be affected
Solution Approach 1:
The active fin is divided into lower and upper portions with a defined interface between them. This segmentation creates a controlled contact area that is sufficient for structural stability while being minimized enough to reduce leakage currents. The clear distinction between portions allows optimization of both structural and electrical properties.
Solution Approach 2:
The contact interface between lower and upper active fin portions is designed with specific local characteristics - sufficient area for mechanical stability but controlled and minimized to reduce leakage pathways. This local quality optimization at the interface resolves the contradiction between structural stability and leakage prevention.
Data Source
AI summary
An active pattern structure includes a lower active pattern protruding from an upper surface of a substrate in a vertical direction substantially perpendicular to an upper surface of the substrate, a buffer structure on the lower active pattern, at least a portion of which may include aluminum silicon oxide, and an upper active pattern on the buffer structure.