Oxide TFT Side-Contact Active Layer for Low Leakage Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Oxide semiconductor thin film transistors face issues with process errors during conductorization, require improved ON-current characteristics, and need to prevent leakage currents in the OFF-state.
Innovation Solution
The thin film transistor design includes a first active layer between the source and drain electrodes, with specific contact points and a bi-layer structure of oxide semiconductor layers to enhance mobility and prevent leakage currents, and a second active layer to support the first layer and suppress leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oxide semiconductor thin film transistor uses conventional conductorization process, then the fabrication can be completed, but process errors occur during conductorization
Solution Approach 1:
The patent extracts the conductorization step from the conventional fabrication process by directly forming source and drain electrodes on the oxide semiconductor active layer without intermediate conductorization treatment. This eliminates the conductorization process and its associated errors, allowing the active layer to be directly electrically connected to the electrodes through optimized contact geometry.
Solution Approach 2:
Instead of conductorizing the oxide semiconductor to make it conductive, the patent inverts the approach by directly depositing conductive electrode materials onto the oxide semiconductor active layer. This reverses the conventional sequence where the semiconductor is modified first, then electrodes are added, achieving both electrical connection and avoiding process errors.
2Ease of manufacture
If the active layer is disposed above the source and drain electrodes, then the fabrication process is conventional, but alignment errors occur and more contact holes are needed
Solution Approach 1:
The patent inverts the conventional top-down approach where the active layer is formed first and electrodes are aligned on top. Instead, it uses a bottom-up approach where source and drain electrodes are formed first, followed by direct deposition of the active layer onto the electrodes, eliminating alignment errors and reducing contact hole requirements.
Solution Approach 2:
The patent transitions from a planar fabrication approach requiring precise 2D alignment to a sequential deposition approach where the active layer is formed in a third dimension directly on the electrode surfaces. This dimensional change eliminates the need for precise lateral alignment between layers.
3Ease of manufacture
If the oxide semiconductor thin film transistor uses conventional structure, then the fabrication is straightforward, but leakage current occurs in OFF-state
Solution Approach 1:
The patent applies local quality by creating specific contact geometries where the active layer contacts only the side surfaces of the source and drain electrodes, not their top surfaces. This localized contact configuration reduces the active area prone to leakage while maintaining necessary electrical connections, effectively suppressing OFF-state leakage current.
4Power
If the active layer thickness is increased to improve ON-current, then the charge transfer is enhanced, but the leakage current increases
Solution Approach 1:
The patent uses local quality by restricting active layer contact to specific side surface regions of the electrodes rather than full surface contact. This localized contact geometry allows sufficient charge transfer for high ON-current through the necessary contact areas while minimizing the total active area that could contribute to leakage, thus decoupling the ON-current and leakage current relationship.
Data Source
AI summary
A thin film transistor, a fabricating method of the thin film transistor and a display device comprising the thin film transistor are provided. The thin film transistor can include a source electrode and a drain electrode disposed on a substrate and spaced apart from each other with a gap area formed therebetween, a first active layer disposed in the gap area between the source electrode and the drain electrode, and a gate insulating layer covering the source electrode, the first active layer and the drain electrode. The thin film transistor can further include a gate electrode disposed on the gate insulating layer and overlapping the first active layer. The first active layer can be in contact with a side of the source electrode and a side of the drain electrode.