Flexible OLED Display with Oriented Polycrystalline Silicon Channel
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Solution Overview
Problem
Flexible display devices using LTPS-TFTs face electrical characteristic deterioration and potential failure under bending stress due to high grain boundary density in the LTPS film, leading to poor electrical uniformity and reliability.
Innovation Solution
A manufacturing method for flexible organic light emitting diodes involves depositing an amorphous silicon film on a flexible substrate, followed by excimer laser annealing to form an oriented crystalline polycrystalline silicon film with reduced grain boundary density, which is then patterned to create a channel for the TFT, along with subsequent formation of a gate, source, drain, OLED display layer, and packaging layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LTPS film is used as channel layer with excimer laser annealing, then electrical parameters (threshold voltage, subthreshold swing, mobility) are improved, but grain boundary density increases causing inter-granular fracture under bending stress
Solution Approach 1:
The patent changes the crystallization parameters by controlling laser annealing conditions to achieve larger grain size and fewer grain boundaries in the LTPS film, thereby improving both electrical characteristics and mechanical strength simultaneously
Solution Approach 2:
The patent uses a composite structure combining LTPS crystalline phase with specific grain boundary characteristics, creating a material that maintains good electrical properties while having enhanced mechanical strength to resist bending stress
2Reliability
If LTPS film with uniform grain size is required, then electrical uniformity is improved, but manufacturing complexity increases due to precise laser annealing control
Solution Approach 1:
The patent optimizes laser annealing parameters (energy density, scanning speed, number of passes) to achieve uniform grain size distribution, improving electrical uniformity while maintaining manufacturing feasibility through parameter optimization rather than process complexity
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 method results in a low grain boundary density along the TFT channel direction, enhancing electrical properties and reliability of the TFT and the flexible display device under bending stress, preventing inter-granular fracture and deformation.
Implementation Method 1
excimer laser annealing the amorphous silicon film which has been processed by the first patterning process to form an oriented crystalline polycrystalline silicon film
Implementation Method 2
performing a crystallization treatment on the amorphous silicon film which has been processed by the first patterning process to form an oriented crystalline polycrystalline silicon film
Data Source
AI summary
A flexible organic light emitting diode display and manufacturing method thereof are provided. The method includes: performing a first patterning process on an amorphous silicon film; performing a crystallization treatment on the amorphous silicon film which has been processed by the first patterning process to form an oriented crystalline polycrystalline silicon film; performing a second patterning process on the polycrystalline silicon film to form a channel; and sequentially forming a gate, a source, a drain, an OLED display layer, and a packaging layer over the channel.