Thin Film Transistor Light-Blocking Pattern for UV Protection
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Solution Overview
Problem
Thin film transistors in display devices are prone to reliability issues due to external light exposure, which deteriorates the semiconductor layer's electrical characteristics, necessitating a solution to prevent this degradation.
Innovation Solution
A thin film transistor substrate is designed with a light-blocking pattern, typically made of silicon-germanium alloy or titanium oxide, positioned between the base substrate and the active pattern, extending to cover the gate and active areas, and formed using the existing gate electrode and semiconductor pattern as a mask, without requiring an additional mask, thus enhancing the light-blocking ability and maintaining the display device's opening ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light-blocking layer is added to protect the channel layer from external light, then the reliability of the thin film transistor is improved, but the device structure becomes more complex and the manufacturing process becomes more difficult
Solution Approach 1:
The light-blocking pattern is merged with the gate electrode structure by using the gate electrode as a mask during the formation process. The gate electrode serves dual purposes: as an electrical component and as a patterning mask for the light-blocking layer, thereby combining multiple functions into a single structural element and reducing overall device complexity.
Solution Approach 2:
The gate electrode serves itself as a mask for forming the light-blocking pattern. Instead of requiring a separate mask layer or additional patterning steps, the gate electrode's own structure is utilized to define the pattern of the light-blocking layer, making the system self-sufficient and reducing manufacturing complexity.
2Reliability
If a light-blocking layer is added to prevent external light from reaching the channel layer, then the electrical characteristics of the semiconductor layer are protected, but the manufacturing process requires additional steps and materials
Solution Approach 1:
The gate electrode serves itself as a mask for forming the light-blocking pattern. Instead of requiring a separate mask layer or additional patterning steps, the gate electrode's own structure is utilized to define the pattern of the light-blocking layer, making the system self-sufficient and reducing manufacturing complexity.
Solution Approach 2:
The light-blocking layer is formed preliminarily during the gate electrode formation process. By utilizing the gate electrode as a mask before completing the full device structure, the light-blocking pattern is established in advance, avoiding the need for separate later patterning steps and simplifying the overall manufacturing sequence.
3Reliability
If the light-blocking pattern is made larger than the active pattern to ensure complete coverage, then the protection against external light is improved, but the opening ratio of the display device is reduced
Solution Approach 1:
The light-blocking pattern is applied locally and selectively only in regions where light blocking is necessary (under and around the active pattern), rather than uniformly across the entire substrate. This localized approach ensures adequate protection while preserving the opening ratio in display regions where light transmission is desired.
Solution Approach 2:
The light-blocking pattern uses materials with specific optical properties (such as ITO or IGZO with appropriate thickness) that selectively block harmful wavelengths while maintaining transparency in the visible range, effectively changing the optical characteristics locally to achieve both protection and display 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
The light-blocking pattern effectively prevents external light from reaching the channel layer, thereby reducing the deterioration of the thin film transistor's electrical characteristics and increasing its reliability by blocking UV rays and other external light sources.
Implementation Method 1
a light-blocking pattern disposed between the base substrate and the active pattern... effectively prevents external light from reaching the channel layer, thereby reducing the deterioration of the thin film transistor's electrical characteristics and increasing its reliability by blocking UV rays and other external light sources
Data Source
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AI summary
A thin film transistor substrate includes a base substrate, an active pattern disposed on the base substrate, a gate insulation pattern disposed on the active pattern, a gate electrode disposed on the gate insulation pattern and overlapping the channel, and a light-blocking pattern disposed between the base substrate and the active pattern and having a size greater than the active pattern. The active pattern includes a source electrode, a drain electrode, and a channel disposed between the source electrode and the drain electrode.