Hybrid TFT OLED Display Structure for Over-Etch Control
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Solution Overview
Problem
In organic light emitting display devices, the over-etching of semiconductor patterns during the manufacturing process affects the performance and reliability of thin film transistors, particularly due to differences in etching conditions for various semiconductor materials, leading to inconsistent electrical characteristics and potential display artifacts at low grayscales.
Innovation Solution
The proposed solution involves an organic light emitting display device structure where doping of source and drain regions is omitted, allowing gate, source, and drain electrodes to be disposed in the same layer, reducing the number of masks and etching steps, and using a combination of polycrystalline and oxide semiconductor patterns with conductive patterns and light shield layers to manage etching and improve transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different semiconductor materials are used for different thin film transistors to achieve different electrical characteristics, then the electrical characteristics can be differentiated, but over-etching occurs during the etching process
Solution Approach 1:
The patent applies local quality by forming a protective conductive pattern selectively on specific semiconductor patterns (source/drain regions) that require protection during etching. This localized protective structure allows different parts of the device to have different properties: protected areas maintain their semiconductor material while unprotected areas undergo etching, thus achieving both differentiated electrical characteristics and preventing over-etching.
2Reliability
If doping process is performed to form source and drain regions, then electrical characteristics can be controlled, but the manufacturing process becomes more complex with additional masks and etching steps
Solution Approach 1:
The patent merges the source/drain region formation with the gate electrode layer by forming conductive patterns in the same layer as the gate electrode. This integration eliminates the need for separate doping processes and additional masks, reducing manufacturing complexity while maintaining control over electrical characteristics through the conductive pattern design.
Solution Approach 2:
The patent replaces the conventional doping process (mechanical/chemical implantation) with a conductive pattern formation approach using screen printing or similar deposition methods. This substitution simplifies the manufacturing process by eliminating complex doping equipment and multiple etching steps while achieving the same electrical function.
3Manufacturing precision
If multiple etching steps are performed to create different patterns, then manufacturing precision can be maintained, but the number of masks and process steps increases
Solution Approach 1:
The patent applies preliminary action by forming the protective conductive pattern on semiconductor patterns before the etching process. This pre-formed protective structure ensures that critical areas are protected during subsequent etching steps, maintaining manufacturing precision while reducing the need for multiple separate masking and etching operations.
Data Source
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AI summary
An organic light emitting display device (100) is disclosed that uses a hybrid type thin film transistor. The organic light emitting display device includes a conductive pattern (415, 475) with a higher etch resistance compared to an inorganic thin film in an upper edge of a semiconductor pattern, and is thereby capable of simplifying a manufacturing process of a substrate (401) on which an array of hybrid type thin film transistors each including multiple layers is disposed, and improving the performance of thin film transistors formed on the array substrate (401). The organic light emitting display device (100) can represent a variety of grayscale images at low grayscales as a driving thin film transistor including an oxide semiconductor pattern is designed to have an increased s-factor value.