Fin-Shaped TFT Channel Structure for Higher Driving Current
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Solution Overview
Problem
Thin film transistors (TFTs) used in back-end-of-line (BEOL) integration face challenges with small driving currents due to limited contact area between source and drain electrodes and the semiconductor channel, and rotating the device structure to increase contact area can lead to misalignment issues.
Innovation Solution
The formation of a fin-shaped semiconductor channel layer that contacts the sidewalls of the source and drain electrodes, extending both vertically and horizontally over fin structures, increases the contact area without increasing the device size and maintains effective alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the device structure is rotated to increase contact area between source/drain electrodes and semiconductor channel, then the driving current is improved, but misalignment issues occur
Solution Approach 1:
The patent transitions from a planar contact geometry to a three-dimensional fin-shaped channel structure. The semiconductor channel is formed with vertical fins that extend upward from the substrate, allowing the source and drain electrodes to contact the channel along the fin sidewalls. This vertical dimension multiplication of contact area enables improved driving current without requiring device rotation, thereby maintaining alignment precision.
Solution Approach 2:
The semiconductor channel is segmented into multiple vertical fin structures rather than a single planar layer. Each fin provides an additional contact surface between the source/drain electrodes and the channel. This segmentation of the channel into discrete vertical elements increases the total contact area and enhances driving current while preserving the horizontal alignment relationship between components.
2Power
If the contact area between source/drain electrodes and semiconductor channel is increased, then the driving current is improved, but the device size increases
Solution Approach 1:
The patent utilizes the vertical dimension by forming fin-shaped channels that extend upward from the substrate. The source and drain electrodes contact the channel along the vertical fin sidewalls, effectively multiplying the contact area without expanding the horizontal device footprint. This vertical expansion of contact area enables improved driving current while maintaining a compact device layout.
Solution Approach 2:
The semiconductor channel is formed as a thin film that is patterned into vertical fin structures. These thin film fins provide large surface area for electrode contact within a small horizontal footprint. The thin film nature allows conformal coverage of the fin sidewalls by the source and drain electrodes, maximizing contact area without increasing device size.
Data Source
AI summary
A transistor device including source and drain electrodes, a fin structure extending between and contacting respective sidewalls of the source and drain electrodes, a semiconductor channel layer over the upper surface and side surfaces of the fin structure and including a first and second vertical portions over the side surfaces of the fin structure, and the first and second vertical portions of the semiconductor channel layer both contact the respective sidewalls of the source electrode and the drain electrode, a gate dielectric layer over the semiconductor channel layer, and a gate electrode over the gate dielectric layer. By forming the semiconductor channel layer over a fin structure extending between sidewalls of the source and drain electrodes, a contact area between the semiconductor channel and the source and drain electrodes may be increased, which may provide increased driving current for the transistor device without increasing the device size.