Oxide Semiconductor TFT Electrostatic Capacity via Hydrogen Diffusion
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Solution Overview
Problem
Conventional thin film transistors (TFTs) using amorphous silicon or poly-silicon as active layers face limitations in mobility and threshold voltage uniformity, and the use of oxide semiconductors as active layers in TFTs struggles to achieve high electrostatic capacity due to the metal-insulator-metal (MIM) capacitor structure, making it difficult to manufacture efficient organic light emitting displays, especially on large area substrates.
Innovation Solution
A method involving the formation of a gate electrode, oxide semiconductor active layer, and capacitor electrodes separated by insulating layers, with hydrogen treatment to enhance the conductivity of the oxide semiconductor, allowing for improved electrostatic capacity and efficient organic light emitting display manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If oxide semiconductor is used as the active layer in TFT, then the TFT can be manufactured at low temperature (no more than 300°C), but the capacitor can only be realized by MIM structure with thick insulating layer, making it difficult to achieve high electrostatic capacity per unit area
Solution Approach 1:
The patent changes the dielectric material parameter from conventional inorganic materials to organic insulating materials, which have higher permittivity. This allows the capacitor to achieve higher electrostatic capacity per unit area while maintaining compatibility with low-temperature oxide semiconductor TFT manufacturing processes
Solution Approach 2:
The patent uses composite material structure combining oxide semiconductor active layer with organic insulating material dielectric layer. The organic insulating material serves as both the dielectric for high-capacity capacitor and the insulating layer for TFT, resolving the contradiction between low-temperature processing and high electrostatic capacity
2Ease of manufacture
If amorphous silicon is used as the active layer, then the manufacturing process is simple, but the mobility is low making it difficult to realize high-speed driving circuits
Solution Approach 1:
The patent changes the semiconductor material parameter from amorphous silicon to oxide semiconductor, which inherently provides higher carrier mobility while maintaining low-temperature processing capability. This resolves the contradiction between manufacturing simplicity and driving circuit speed
3Speed
If poly-silicon is used as the active layer, then the mobility is high, but the threshold voltage is not uniform requiring additional compensation circuits
Solution Approach 1:
The patent changes the semiconductor material parameter from poly-silicon to oxide semiconductor, which provides both high carrier mobility and uniform threshold voltage characteristics. This eliminates the need for compensation circuits while maintaining high-speed performance
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
This method enables the production of organic light emitting displays with enhanced electrostatic capacity and conductivity, overcoming the limitations of conventional TFTs and allowing for high-quality, large-area substrate manufacturing.
Implementation Method 1
bathing the additional insulating layer in a solution including hydrogen, where the hydrogen diffuses into the oxide semiconductor material of the capacitor
Data Source
AI summary
An organic light emitting display is disclosed. The display has a pixel which includes a transistor and a capacitor. The active layer of the transistor and at least one of the electrodes of the capacitor comprise a semiconductor oxide.