Oxide TFT Light Shield via Source Metal Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Active matrix organic light emitting display devices face issues with light sensitivity of oxide TFTs, leading to hot spots, dark spots, reduced boosting efficiency, and increased power consumption, along with the need for multiple masks in manufacturing, which complicates the process and increases costs.
Innovation Solution
The use of a light shield formed from the same metal as the source and drain, acting as both a gate and a light blocker, reduces light exposure to the active layer and simplifies the manufacturing process by reducing the number of masks required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a separate light shield is formed to block light from the oxide TFT, then light exposure is reduced, but the number of masks increases and manufacturing complexity increases
Solution Approach 1:
The patent combines the light shield function with the source/drain electrode structure by forming the light shield using the same metal layer as the source/drain electrode. This integration eliminates the need for a separate light shield structure and reduces the number of manufacturing masks while effectively blocking light from reaching the oxide TFT active layer.
Solution Approach 2:
The source/drain metal layer is given dual functionality: it serves as both the electrical conductor (source/drain electrode) and as the light shield. By making the metal layer thicker or extending it underneath the active layer, it simultaneously performs electrical connection and light blocking functions, reducing manufacturing steps.
2Manufacturing precision
If multiple masks are used in manufacturing, then precise patterning is achieved, but manufacturing efficiency decreases and costs increase
Solution Approach 1:
The patent merges the light shield formation step with the source/drain electrode formation step into a single manufacturing process. By using the same metal deposition and patterning step for both structures, the number of masks is reduced from multiple to fewer steps, improving manufacturing efficiency while maintaining the necessary patterning precision through proper mask design.
3Reliability
If light shields are added to block light, then image quality improves, but device structure becomes more complex
Solution Approach 1:
The light shield is integrated into the existing source/drain electrode structure rather than being added as a separate component. The same metal layer that forms the electrical connection also serves as the light-blocking structure, eliminating the need for additional light shield layers or structures while effectively preventing light-induced degradation of the oxide TFT.
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 approach effectively blocks light from reaching the oxide TFT, enhancing image quality, reducing power consumption, and increasing manufacturing efficiency by minimizing the number of masks needed, thereby improving the overall performance and production efficiency of organic light emitting display devices.
Implementation Method 1
a lower gate, a source, and a drain formed on a substrate and on the same layer; a first gate insulating layer formed to cover the lower gate, the source, and the drain; an active layer formed on the first gate insulating layer... the lower gate of the switching TFT is a light shield that blocks light from being irradiated onto the active layer
Data Source
AI summary
An organic light emitting display device includes a driving thin film transistor (TFT), the driving thin film TFT includes a lower gate, a source, and a drain on a substrate and on the same layer; a first gate insulating layer covering the lower gate, the source, and the drain; an active layer on the first gate insulating layer; a conductive line contacting the source and the drain; a second gate insulating layer on the active layer; and an upper gate on the second gate insulating layer, wherein the lower gate of the driving TFT is a light shield that blocks light from being irradiated onto the active layer, and the lower gate and the source include the same metal.