Bottom-Gate Thin Film Transistor Oxygenation Interface
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Solution Overview
Problem
Conventional bottom-gate thin film transistors face issues with poor adhesion and crystallinity between microcrystalline silicon films and silicon nitride gate insulating layers, leading to asymmetric brightness in display panels due to the low adhesion and poor interface quality.
Innovation Solution
Incorporating an oxygenation surface treatment to increase the oxygen concentration at the interface between the silicon nitride gate insulating layer and the microcrystalline silicon layer, ranging between 1020 and 1025 atoms/cm3, to enhance adhesion and crystallinity, using PECVD with specific gas ratios and forming conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a microcrystalline silicon film is formed on a silicon nitride gate insulating layer to solve threshold voltage shifts, then the display panel brightness symmetry is improved, but the adhesion between the microcrystalline silicon film and gate insulating layer deteriorates due to low adhesion and poor interface quality
Solution Approach 1:
An oxygenation surface treatment is performed on the silicon nitride gate insulating layer before forming the microcrystalline silicon film. This preliminary action modifies the surface chemistry of the gate insulating layer, creating oxygen-containing groups that enhance adhesion to the subsequently deposited microcrystalline silicon film, thereby preventing peeling while maintaining brightness symmetry
Solution Approach 2:
The oxygen concentration at the contact interface between the gate insulating layer and microcrystalline silicon layer is controlled within a specific range (10^20 to 10^25 atoms/cm³). By optimizing this parameter through oxygenation treatment, the patent achieves both improved adhesion and maintained brightness symmetry without the peeling issues of conventional approaches
2Stability of the object's composition
If a microcrystalline silicon film is formed on a silicon nitride gate insulating layer, then the threshold voltage shift problem is addressed, but the crystallinity of the thin film interface deteriorates resulting in poor overall microcrystalline silicon film crystallinity
Solution Approach 1:
The oxygenation surface treatment is applied to the silicon nitride gate insulating layer before microcrystalline silicon film deposition. This preliminary modification creates a surface with improved crystalline structure and oxygen-containing groups that serve as nucleation sites, enabling the formation of high-quality crystalline microcrystalline silicon film with proper threshold voltage characteristics
Solution Approach 2:
By controlling the oxygen concentration at the interface (10^20 to 10^25 atoms/cm³) through oxygenation treatment, the patent optimizes the crystalline structure of the microcrystalline silicon film. This parameter control ensures both threshold voltage stability and high crystallinity, avoiding the amorphous or porous film formation seen in conventional processes
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 oxygenation surface treatment significantly improves the crystallinity and adhesion of the microcrystalline silicon film, resulting in enhanced stability and characteristics of the thin film transistor, as evidenced by reduced threshold voltage shifts and improved Raman spectrum and bias-temperature-stress test results.
Implementation Method 1
performing an oxygenation surface treatment for a surface of the silicon nitride layer
Implementation Method 2
when plasma enhanced chemical vapor deposition (PECVD) is employed to form the microcrystalline silicon film
Data Source
AI summary
A bottom-gate thin film transistor includes a gate electrode, a gate insulating layer and a microcrystalline silicon layer. The gate electrode is disposed on a substrate. The gate insulating layer is made up of silicon nitride and disposed on the gate electrode and the substrate. The microcrystalline silicon layer is disposed on the gate insulating layer and corresponds to the gate electrode, in which a contact interface between the gate insulating layer and the microcrystalline silicon layer has a plurality of oxygen atoms, and concentration of the oxygen atoms ranges between 1020 atoms/cm3 and 1025 atoms/cm3. A method of fabricating a bottom-gate thin film transistor is also disclosed herein.