Organic Thin Film Transistor Patterning via Protective Mask
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Solution Overview
Problem
Organic thin film transistors with pentacene semiconductor layers face challenges in achieving high resolution and minute patterns due to limitations in shadow mask technology, resulting in low mobility and stability, and damage during photoresist removal processes.
Innovation Solution
The use of a first protection layer made of photoacrylate or poly vinyl alcohol as a mask during patterning of the organic semiconductor layer, which remains on the layer post-processing, preventing damage and allowing for precise patterning and improved stability, along with a second protection layer for complete coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shadow mask technology is used for patterning the semiconductor layer, then the fabrication process is simple, but the minimum pattern width is limited to about 40 μm and the minimum pattern interval is about 120 μm, making it difficult to achieve high resolution and minute patterns
Solution Approach 1:
The patent replaces the mechanical shadow mask system with a chemical/photochemical patterning system. Specifically, it uses a photoresist layer that can be exposed and developed to create patterns, substituting the mechanical shadow mask approach with a photochemical process that enables much finer pattern resolution beyond the 40 μm width and 120 μm interval limitations of shadow masks
Solution Approach 2:
The patent changes the patterning parameters by transitioning from shadow mask physical dimensions to photoresist exposure parameters. By controlling exposure dose, development time, and photoresist thickness, the process achieves pattern dimensions much smaller than the 40 μm minimum achievable with shadow masks, enabling high-resolution patterning
2Manufacturing precision
If photoresist removal process is used for patterning, then higher resolution patterns can be achieved, but the semiconductor layer may be damaged during the removal process
Solution Approach 1:
The patent introduces an intermediary protective layer between the photoresist and the semiconductor layer. This protective layer absorbs or mitigates the harmful effects of the photoresist removal process, preventing damage to the semiconductor layer while still allowing the photoresist to serve its patterning function. The intermediary layer acts as a buffer that protects the sensitive semiconductor material during chemical processing
Solution Approach 2:
The patent applies a protective coating on the semiconductor layer before applying the photoresist. This beforehand cushioning ensures that when the photoresist removal process occurs, the semiconductor layer is already protected and will not be damaged by solvents or mechanical stresses during removal, thus maintaining both high resolution patterning and semiconductor layer integrity
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 enables the creation of organic thin film transistors with higher mobility and stability, allowing for the production of flexible and high-resolution devices without damaging the semiconductor layer during processing.
Implementation Method 1
a gate electrode 120 is formed on a substrate 100, and a gate insulating layer 140 is formed on an entire surface of the substrate 100 including the gate electrode 120
Implementation Method 2
a deposition process is performed thereon
Data Source
AI summary
An organic thin film transistor and a method for fabricating the same are disclosed. The method for fabricating the organic thin film transistor includes forming a gate electrode on a substrate. A gate insulating layer is formed on an entire surface of the substrate including the gate electrode, and source and drain electrodes are formed at a predetermined interval from each other on the gate insulating layer. An organic semiconductor layer is formed on the entire surface of the substrate and a first protection layer is formed on the organic semiconductor layer. The first protection layer is patterned and the organic semiconductor layer etched using the remaining first protection layer as a mask. A second protection layer is then formed on the entire surface of the substrate.