TFT Array Substrate Light Absorption Layer Design
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Solution Overview
Problem
In thin film transistor (TFT) devices, light reflection between metal layers affects the performance and lifetime due to the use of metal materials for the gate, source, drain, and light-shielding layers, which causes light to be reflected onto the active layer.
Innovation Solution
A light absorption layer is introduced, typically formed using a black photoresist, either on one side of the light shielding layer close to the active layer or below the source/drain metal layer, to absorb reflected light and prevent it from reaching the active layer, thereby improving device performance without adding new processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal materials are used for gate, source, drain, and light-shielding layer, then electrical conductivity and device performance are improved, but light reflection between metal layers occurs which affects active layer performance and device lifetime
Solution Approach 1:
A light absorption layer is introduced as an intermediary component between the metal layers and the active layer. This layer absorbs the reflected light from metal layers, preventing it from reaching the active layer and causing damage, thereby resolving the contradiction between using metal materials for electrical performance and preventing light reflection harm.
2Object-affected harmful factors
If a light absorption layer is added to prevent light reflection, then protection of the active layer is improved, but device structure complexity increases
Solution Approach 1:
The light absorption layer is merged with existing fabrication processes by utilizing the black photoresist already applied during light-shielding layer formation. The black photoresist serves dual purposes: as an etching mask for pattern formation and as a light absorption layer for protecting the active layer, thereby reducing structure complexity despite adding protective functionality.
3Object-affected harmful factors
If black photoresist is used as light absorption layer, then light reflection is reduced, but additional processing steps are required
Solution Approach 1:
The black photoresist is designed to perform multiple functions: serving as an etching mask for defining the light-shielding layer pattern and simultaneously functioning as a light absorption layer to protect the active layer from reflected light. This multi-functionality eliminates the need for separate light absorption layer fabrication steps, maintaining process simplicity while achieving light reflection reduction.
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 absorption layer effectively reduces light reflection onto the active layer, enhancing the performance and longevity of TFT devices while simplifying the fabrication process and saving costs by not requiring additional processing steps.
Implementation Method 1
a light absorption layer is prepared on one side of the light shielding layer close to the active layer
Data Source
AI summary
A preparation method of a thin film transistor (TFT) array substrate includes a step of providing a substrate to prepare a light shielding layer and a buffer layer in sequence on the substrate; and a step of preparing an active layer, a gate insulation layer, a gate, an interlayer insulation layer, and a source/drain metal layer in sequence on the buffer layer; wherein a light absorption layer is prepared on one side of the active layer. Absorbing light prevents most of the light from being reflected to the active layer by disposing a black photoresist below a source and a drain or over the light shielding layer, thereby improving performance of TFT devices.