Hybrid TFT OLED Display Layout to Prevent Semiconductor Over-Etching
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Solution Overview
Problem
In organic light emitting display devices, the over-etching of semiconductor patterns during manufacturing poses a challenge, particularly in forming thin film transistors with different electrical characteristics, leading to instability and inefficiency in grayscale representation and on-off operation.
Innovation Solution
The proposed solution involves an organic light emitting display device structure where the doping process for source and drain regions is omitted, allowing gate, source, and drain electrodes of transistors to be disposed in or on the same layer, reducing the number of masks and preventing over-etching by using conductive patterns and light shield patterns to protect semiconductor patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If doping process is performed to form source and drain regions in thin film transistors, then electrical characteristics of transistors can be controlled, but semiconductor patterns in lower layers are over-etched during manufacturing
Solution Approach 1:
The patent extracts and removes the doping process from the manufacturing flow. Instead of forming source and drain regions through doping, the invention uses undoped semiconductor layers with conductive patterns formed on top, thereby eliminating the over-etching problem while maintaining transistor functionality.
Solution Approach 2:
The patent makes the semiconductor layer serve multiple functions: it acts as both the active channel region and the source/drain region structure, eliminating the need for separate doped source/drain regions. This multi-functional approach simplifies the structure and prevents over-etching.
2Reliability
If multiple layers with different semiconductor materials are formed to achieve different electrical characteristics, then transistor performance can be optimized, but the number of masks and manufacturing complexity increase
Solution Approach 1:
The patent applies local quality by forming conductive patterns with different materials (such as metal patterns) on specific regions of the semiconductor layer. This allows different electrical characteristics to be achieved in different areas without requiring multiple semiconductor layers, thus reducing manufacturing complexity.
Solution Approach 2:
The patent changes the electrical parameters by varying the conductive pattern material and configuration on the semiconductor layer rather than changing the semiconductor material itself. This approach achieves different transistor characteristics while maintaining a single semiconductor layer structure.
3Adaptability or versatility
If doping is used to form source and drain regions, then transistor electrical characteristics can be adjusted, but the S-factor control for grayscale representation becomes difficult
Solution Approach 1:
The patent achieves S-factor control by changing the geometric parameters and material properties of the conductive patterns on the semiconductor layer. By adjusting the width, length, and material of these patterns, precise control over transistor characteristics including S-factor is achieved without doping.
Data Source
AI summary
An organic light emitting display device is disclosed that uses a hybrid type thin film transistor. The organic light emitting display device includes a conductive pattern 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 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. The organic light emitting display device 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.