Thin Film Transistor Mobility Enhancement Layer
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Solution Overview
Problem
Thin film transistors are prone to active layer damage during etching, leading to reduced device characteristics due to a decreased contact area between the source/drain and active layers, which in turn reduces carrier mobility.
Innovation Solution
Incorporating a mobility enhancement layer above or below the active layer in the thin film transistor structure, utilizing a low electronegativity element to form vacancies and enhance carrier mobility, thereby increasing carrier density and reducing subgap density at tail states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an etch stop layer is used to protect the active layer during etching, then the active layer is protected from damage, but the contact area between the source/drain layer and active layer is reduced
Solution Approach 1:
The patent introduces a mobility enhancement layer as an intermediary component between the active layer and source/drain layer. This layer serves multiple functions: it protects the active layer during etching processes while simultaneously enhancing carrier mobility through its specific material composition, thereby resolving the contradiction between protection and contact area reduction
Solution Approach 2:
The mobility enhancement layer is formed using composite material composition (such as ITO with specific doping elements) that combines the protective function against etching damage with the electrical function of enhancing carrier mobility, thus addressing both the protection requirement and the contact area constraint
2Reliability
If the contact area between source/drain layer and active layer is reduced, then the etch stop layer protection is improved, but the carrier mobility is reduced
Solution Approach 1:
The mobility enhancement layer acts as a mediator that decouples the protection function from the electrical performance function. It provides etch protection to the active layer while its specific material properties (low electronegativity, vacancy formation) actively enhance carrier mobility, thus resolving the contradiction between protection and mobility
3Manufacturing precision
If the carrier mobility of the active layer is enhanced, then the device characteristics are improved, but the structure complexity increases
Solution Approach 1:
The mobility enhancement layer is designed to perform multiple functions simultaneously: it serves as an etch stop layer protecting the active layer, enhances carrier mobility through its material composition, and provides a platform for source/drain layer formation. This multi-functionality reduces the need for separate protective layers, thereby limiting the increase in structure complexity while achieving improved device characteristics
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
The mobility enhancement layer effectively enhances carrier mobility from 10 cm2V−1s−1 to 80 cm2V−1s−1, improving device characteristics by increasing carrier density and reducing defects in the active layer.
Implementation Method 1
utilizing a low electronegativity element to form vacancies and enhance carrier mobility
Data Source
AI summary
A thin film transistor disposed on a substrate is provided. The TFT includes a gate layer, an insulation layer, a carrier transmission layer, a passivation layer, a first source/drain layer, and a second source/drain layer. The gate layer is disposed on the substrate. The insulation layer is disposed on the gate layer. The carrier transmission layer is disposed on the insulation layer. The carrier transmission layer includes an active layer and a mobility enhancement layer. The passivation layer is disposed on the active layer. The first source/drain layer is disposed on the active layer. The second source/drain layer is disposed on the active layer. The mobility enhancement layer includes a first element. The active layer includes a second element. The electronegativity of the first element is smaller than that of the second element to enhance the carrier mobility of the active layer.