Thin Film Transistor Light-Shielding Layer Using Transparent Conductive Oxide
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Solution Overview
Problem
Existing thin film transistors face issues with light-induced deterioration due to the use of non-transparent metal light-shielding layers, which require different etching rates and masks, leading to increased processing costs and reduced light reliability.
Innovation Solution
A thin film transistor with a light-shielding layer made of the same material as the semiconductor layer, using transparent conductive oxides like zinc oxide (ZnO), indium zinc oxide (IZO), or indium tin oxide (ITO), which absorbs light and minimizes exposure to the semiconductor layer, allowing for simplified processing and improved insulating properties with a thinner buffer layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a non-transparent metal light-shielding layer is used, then light shielding effectiveness is improved, but processing complexity increases due to requiring different etching rates and masks
Solution Approach 1:
The patent applies homogeneity by making the light-shielding layer and semiconductor layer consist of the same material (transparent conductive oxide). This eliminates the need for different etching rates and separate masks, as both layers can be patterned using the same photolithography process, thereby reducing processing complexity while maintaining light shielding effectiveness
Solution Approach 2:
The transparent conductive oxide layer serves multiple functions: it acts as both the light-shielding layer and the semiconductor layer material. This multi-functionality eliminates the need for separate material systems and processing steps for light shielding and semiconductor formation, resolving the contradiction between light shielding effectiveness and processing complexity
2Object-affected harmful factors
If a non-transparent metal light-shielding layer is used, then light shielding is achieved, but manufacturing cost increases due to additional masks and processing steps
Solution Approach 1:
The patent merges the light-shielding function and semiconductor layer formation by using the same transparent conductive oxide material for both. This consolidation eliminates the need for separate masks and processing steps for light shielding, directly reducing manufacturing cost while maintaining effective light shielding
Solution Approach 2:
By using homogeneous material (transparent conductive oxide) for both light shielding and semiconductor functions, the patent eliminates material compatibility issues and reduces the number of processing steps required, thereby lowering manufacturing cost
3Reliability
If a thick buffer layer is used with non-transparent metal light-shielding layer, then sufficient insulation is achieved, but device area increases
Solution Approach 1:
The patent changes the material parameter of the light-shielding layer from non-transparent metal to transparent conductive oxide. This material change enables the buffer layer to be made thinner because the transparent conductive oxide provides both insulation and light shielding functions, reducing device area while maintaining insulation reliability
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 solution enhances light reliability and reduces manufacturing costs by eliminating the need for additional masks and ensuring that light is absorbed by the light-shielding layer, thereby maintaining transistor properties and reducing power consumption.
Implementation Method 1
transparent conductive oxides like zinc oxide (ZnO), indium zinc oxide (IZO), or indium tin oxide (ITO), which absorbs light and minimizes exposure to the semiconductor layer
Data Source
AI summary
Disclosed is a thin film transistor and a method of fabricating the same which includes a light-shielding layer made of the same material as a semiconductor layer on a substrate, wherein the light-shielding layer absorbs light incident upon the semiconductor layer, thereby preventing deterioration in characteristics of the thin film transistor caused by exterior light.