Oxide Semiconductor TFT Low Reflecting Layer Stray Light
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Solution Overview
Problem
Conventional oxide semiconductor TFTs fail to adequately prevent visible radiation from entering the semiconductor layer, leading to shifts in threshold value and potential malfunction, especially in display devices using backlights or exposed to external light.
Innovation Solution
A low reflecting layer with low reflectance to visible radiation is introduced between the source/drain electrodes and the oxide semiconductor layer, formed through an oxidation reduction reaction, to reduce stray light incidence and maintain contact without complicating the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a gate electrode is arranged closer to the substrate than the oxide semiconductor layer to prevent light entry, then light blocking function is improved, but the gate electrode still allows stray light reflection and threshold value shift occurs
Solution Approach 1:
A low reflecting layer is introduced as an intermediary component between the source/drain electrodes and the oxide semiconductor layer. This layer mediates the interaction by reducing stray light reflection while maintaining electrical functionality, thereby preventing threshold value shifts without compromising the light blocking capability of the gate electrode structure.
Solution Approach 2:
The low reflecting layer is specifically positioned in regions where stray light reflection occurs (between source/drain electrodes and oxide semiconductor layer) rather than uniformly across the entire device. This localized application addresses the specific problem of stray light reflection without adding unnecessary complexity to the overall structure.
2Reliability
If a low reflecting layer is added to reduce stray light, then threshold value stability is improved, but device structure becomes more complex
Solution Approach 1:
The low reflecting layer is merged with existing electrode structures (source/drain electrodes) rather than being implemented as a completely separate component. This integration approach reduces the overall device complexity by combining multiple functions into a unified structure, thereby improving threshold value stability without significantly increasing structural complexity.
Solution Approach 2:
The low reflecting layer serves multiple functions simultaneously: it reduces stray light reflection, maintains electrical contact between electrodes and oxide semiconductor layer, and potentially provides additional protective functionality. This multi-functionality reduces the need for separate components, thereby improving reliability without proportionally increasing device complexity.
3Object-affected harmful factors
If additional layers are introduced to block light, then light blocking performance is improved, but manufacturing process becomes more complex
Solution Approach 1:
The low reflecting layer is formed preliminarily during the existing manufacturing process sequence, specifically after forming the oxide semiconductor layer and before forming the source/drain electrodes. This preliminary action integrates light blocking functionality into the standard manufacturing flow without requiring additional standalone process steps, thereby improving stray light reduction while maintaining ease of manufacture.
Solution Approach 2:
The manufacturing process utilizes parameter changes (such as sputtering conditions, deposition temperature, or material composition ratios) to form the low reflecting layer with appropriate optical and electrical properties. By controlling process parameters rather than adding fundamentally new process steps, the manufacturing complexity is minimized while achieving the desired light blocking 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
This solution effectively prevents visible radiation from entering the oxide semiconductor layer, reducing threshold value shifts and enhancing the reliability of the TFTs while maintaining productivity.
Implementation Method 1
formed through an oxidation reduction reaction
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3(a)~3(h)
AI summary
A semiconductor device (1001) includes a thin-film transistor (103) including a gate electrode (3a), source and drain electrodes (13as, 13ad), and an oxide semiconductor layer (7), and a source bus line (13s). The source electrode, the source bus line and the drain electrode include a first metallic element and the oxide semiconductor layer includes a second metallic element. When viewed along a normal to its substrate, at least respective portions of the source electrode, the source bus line, and the drain electrode overlap with the oxide semiconductor layer. A low reflecting layer (4s, 4d) which includes the first and second metallic elements and which has a lower reflectance to visible radiation than the source electrode has been formed between the source electrode and the oxide semiconductor layer, between the source bus line and the oxide semiconductor layer, and between the drain line and the oxide semiconductor layer.