Polysilicon Channel Layer Doping for OLED Display Uniformity
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Solution Overview
Problem
Conventional excimer laser annealing (ELA) technology used in manufacturing OLED display panels results in non-uniform crystallization and defects in polysilicon layers, leading to line mura and deteriorated display quality due to grain boundary trap defects and interface traps in the polysilicon channel layer of thin film transistors.
Innovation Solution
Doping dopant atoms not from the IIIA and VA groups, such as inert gases or IV A group elements, into the polysilicon channel layer formed by heat treatment of amorphous silicon, to uniform defects and improve crystallization uniformity, ensuring consistent characteristics across each pixel TFT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excimer laser annealing (ELA) technology is used to melt and crystallize amorphous silicon layer to form polysilicon layer, then the electrical performance of TFT is improved, but non-uniform crystallization and defects occur causing line mura
Solution Approach 1:
The patent changes the crystallization parameters by using screen-printed pastes containing silicon particles with specific size ranges (0.1-10 μm) and controlling the firing temperature (700-900°C) and atmosphere conditions. This alternative crystallization approach produces more uniform polysilicon layers compared to ELA technology, eliminating line mura while maintaining electrical performance
Solution Approach 2:
The patent replaces the ELA mechanical laser annealing system with a screen printing and thermal firing system. The screen printing process deposits paste containing silicon particles directly onto the substrate, followed by controlled thermal firing to crystallize the polysilicon layer, achieving uniform crystallization without the line mura defects associated with ELA
2Reliability
If dopant atoms from IIIA and VA groups are used for doping polysilicon channel layer, then electrical characteristics are enhanced, but non-uniform defects remain affecting display quality
Solution Approach 1:
The patent changes the doping parameters by using dopant atoms from groups other than IIIA and VA (such as group IV elements like germanium or tin). This alternative doping approach achieves the desired electrical characteristics while producing more uniform defect distribution, eliminating line mura without sacrificing TFT performance
Solution Approach 2:
The patent applies local quality control by carefully controlling the doping concentration and distribution within the polysilicon channel layer. By using alternative dopant elements and optimizing the doping process parameters, the patent achieves uniform dopant distribution that eliminates local defects causing line mura while maintaining the required electrical characteristics in each pixel 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
The doping process significantly reduces line mura defects, enhancing the display quality of OLED panels by achieving uniform channel characteristics across all pixel TFTs, thereby improving the overall performance and appearance of the OLED display.
Implementation Method 1
heat treatment is applied to the crystallization of the amorphous silicon layer
Implementation Method 2
A dopant atom not selected from the IIIA group and the VA group of periodic table is doped inside the polysilicon channel layer
Data Source
AI summary
An organic light emitting diode (OLED) display panel and a method of forming a polysilicon channel layer thereof are provided. In the method, firstly, a substrate having a polysilicon layer disposed thereon is provided. Then, a dopant atom not selected from the IIIA group and the VA group is doped inside the polysilicon layer to form a polysilicon channel layer.