Double Gate LCD Transistor Light Blocking
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Solution Overview
Problem
In liquid crystal display devices, external light can intrude into the semiconductor layer of thin film transistors, causing optical and thermal stresses that degrade the transistor's characteristics and lead to current leakage, affecting the display's performance and picture quality.
Innovation Solution
A liquid crystal display device with a double gate structure is implemented, where two metal layers are positioned over and under the semiconductor layer, using opaque conductive materials like Mo and Ti, and transparent conductive materials like ITO or IZO, to block light intrusion and enhance electron mobility and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single gate structure is used, then the manufacturing process is simpler, but light can intrude into the semiconductor layer causing optical and thermal stresses that degrade transistor characteristics
Solution Approach 1:
The gate structure is segmented into two separate gates: a lower gate formed on the lower substrate and an upper gate formed on the upper substrate. This segmentation allows each gate to independently block light from its respective side, preventing light intrusion into the semiconductor layer while maintaining manufacturing feasibility through separate formation processes.
Solution Approach 2:
The protection against light intrusion is achieved by adding a vertical dimension to the blocking structure. Instead of a single horizontal barrier, the solution introduces an upper gate on the upper substrate that blocks light from above, complementing the lower gate that blocks light from below, creating a three-dimensional light blocking configuration.
2Area of moving object
If the transistor size is reduced to increase aperture ratio, then the display performance improves, but the transistor becomes more susceptible to light intrusion and degradation
Solution Approach 1:
By segmenting the gate structure into upper and lower gates, the solution provides comprehensive light blocking coverage that scales with reduced transistor size. Each gate independently protects against light from its side, ensuring that even smaller transistors are fully protected from light intrusion while maintaining high aperture ratio.
Solution Approach 2:
The upper and lower gates are positioned beforehand to block light before it can reach the semiconductor layer. This preventive structure cushions the semiconductor layer against optical and thermal stresses by intercepting light at the gate level, protecting the transistor even when scaled down to smaller dimensions.
3Object-affected harmful factors
If opaque conductive materials like Mo and Ti are used for the gates, then light blocking effectiveness is improved, but the manufacturing complexity increases
Solution Approach 1:
The gate formation process is segmented into separate steps for the lower gate and upper gate. Each gate can be formed using standard opaque conductive materials like Mo or Ti through conventional deposition techniques, allowing the use of proven materials and processes while achieving comprehensive light blocking through the segmented structure.
Solution Approach 2:
The light blocking function is distributed across two dimensions (lower substrate and upper substrate) rather than requiring a single complex material layer. This allows the use of standard opaque conductive materials in each gate formation, leveraging existing manufacturing capabilities while achieving superior light blocking through the vertical arrangement.
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 effectively prevents light from entering the semiconductor layer, improving the reliability and performance of thin film transistors, maintaining picture quality over time, and allowing for a smaller transistor size with higher aperture ratio.
Implementation Method 1
an opaque protective layer which is formed on the passivation layer and covers the thin film transistor
Data Source
AI summary
The present disclosure relates to a liquid crystal display device having a protection element for semiconductor layer from externally intruding light and a manufacturing method of the same. The present disclosure suggests a liquid crystal display device comprising a substrate; a data line and a gate line crossing each other on the substrate; a thin film transistor formed at a crossing portion of the data line and the gate line; a passivation layer covering the thin film transistor; and an opaque protective layer forming on the passivation layer and covering the thin film transistor. The liquid crystal display device according to the present disclosure blocks the light intrusion into the semiconductor active layer of the thin film transistor to enhance the electron mobility in the active layer and the reliability of the elements.