Thin Film Transistor With Segmented Active Pattern For Leakage Current Reduction
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Solution Overview
Problem
Thin film transistors in transparent display devices experience increased leakage current due to light irradiation on the back surface of the display panel, which affects the channel layer characteristics and off-current levels.
Innovation Solution
A thin film transistor design incorporating a first and second blocking layer, with the active pattern having different thicknesses and specific overlapping regions, and contact parts to block light incident on the substrate, minimizing light exposure to the channel and drain-channel contact areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the display panel uses a transparent structure allowing light irradiation on the back surface, then the display device achieves transparency and aesthetic appearance, but light exposure to the channel layer causes increased leakage current and degraded transistor performance
Solution Approach 1:
The active pattern is divided into multiple thickness regions: a first part with greater thickness and a second part with lesser thickness. This segmentation allows different portions of the active pattern to serve different functions - the thicker first part provides better light blocking capability, while the thinner second part maintains electrical performance, thus resolving the contradiction between transparency and leakage current stability.
Solution Approach 2:
Different regions of the active pattern are given different thicknesses to optimize local properties. The first part (with greater thickness) is positioned where light blocking is most needed, while the second part (with lesser thickness) is positioned to maintain electrical conductivity. This local differentiation allows the structure to simultaneously achieve light transparency and leakage current stability.
2Ease of manufacture
If the active pattern is made with uniform thickness to simplify manufacturing, then the fabrication process becomes easier, but the transistor cannot effectively block light-induced leakage current
Solution Approach 1:
The active pattern is segmented into thickness regions that can be formed through controlled doping processes. The segmentation is achieved by varying doping conditions across different regions of the active pattern, which is a standard semiconductor manufacturing technique. This approach maintains manufacturing feasibility while achieving the light-blocking function.
Solution Approach 2:
The thickness parameter of the active pattern is varied across different regions to achieve the desired light-blocking effect. By changing the thickness parameter locally, the structure can block light-induced leakage current while still being manufacturable using conventional semiconductor processing techniques that control layer thickness and doping profiles.
3Reliability
If blocking layers are added to prevent light exposure to the channel region, then leakage current is reduced, but the device structure becomes more complex
Solution Approach 1:
The light-blocking function is merged with the active pattern itself rather than being implemented as a separate blocking layer. By integrating the light-blocking capability into the active pattern through thickness variation, the structure achieves both transistor functionality and light blocking without adding separate blocking layers, thus reducing overall device complexity.
Solution Approach 2:
The active pattern is given multiple functions: it serves as the conductive path for current flow and simultaneously acts as a light-blocking structure through its varied thickness. This multi-functionality eliminates the need for separate dedicated blocking layers, reducing device complexity while maintaining reliable off-current stability.
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 design effectively reduces leakage current in thin film transistors even when light is irradiated onto the back surface of the display panel, maintaining stable off-current levels.
Implementation Method 1
the first blocking layer partially overlaps with the source region and the channel region... the drain-channel contact part is covered by the first blocking layer to block light that is incident onto a surface of the substrate
Data Source
AI summary
A thin film transistor includes a first blocking layer disposed on a substrate, and an active pattern disposed on the first blocking layer. The active pattern includes a source region, a drain region, and a channel region disposed between the source region and the drain region. The thin film transistor further includes a gate electrode disposed on the active pattern. The channel region corresponds to a portion of the active pattern overlapped by the gate electrode. The thin film transistor additionally includes a source electrode connected to the source region, and a drain electrode connected to the drain region. The active pattern includes a first part and a second part. The first part partially overlaps with the first blocking layer, and the first part and the second part have different thicknesses from each other.