TFT Semiconductor Film Thickness Control via Liquid-Philic Layer
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Solution Overview
Problem
The cross-sectional shape of semiconductor layers in TFTs formed by coating methods can lead to undesirable properties due to variations in film thickness, particularly near the center and edges of the aperture, resulting in transistor degradation.
Innovation Solution
An electronic device configuration featuring a substrate with a bank and a liquid-philic layer on the peripheral area, where the semiconductor layer is formed within the aperture and attaches to the central portion and the liquid-philic layer, preventing semiconductor ink from climbing the bank's lateral surface, thus maintaining a consistent film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bank's lateral surface is made liquid-phobic to prevent semiconductor ink from climbing, then the film thickness near the inner edge increases, but the film thickness at the center becomes insufficient
Solution Approach 1:
The patent applies local quality by creating different liquid interaction properties at different locations: the bank lateral surface is made liquid-phobic to repel ink, while a liquid-philic layer is added at the bottom center to attract and retain ink, ensuring adequate film thickness at the center without excessive thickness at the edges
Solution Approach 2:
The liquid-philic layer acts as an intermediary element between the substrate and the semiconductor ink. This intermediate layer with high liquid affinity captures and holds the ink in the central region, preventing the ink from being completely repelled by the liquid-phobic bank walls, thus mediating between the conflicting requirements of edge thickness control and center thickness maintenance
2Quantity of substance
If the semiconductor ink is allowed to climb the bank's lateral surface, then the film thickness near the inner edge increases, but the cross-sectional shape becomes undesirable and degrades transistor properties
Solution Approach 1:
The patent implements local quality by spatially differentiating the liquid interaction properties: liquid-phobic treatment on the bank lateral surfaces prevents unwanted ink climbing and accumulation at edges, while a localized liquid-philic layer at the bottom center encourages appropriate ink retention, thereby achieving desirable cross-sectional shape with controlled material distribution
3Reliability
If the semiconductor layer film thickness is increased at the center, then the transistor properties improve, but the film thickness at the inner edge becomes excessively large
Solution Approach 1:
The patent applies local quality by creating spatially varying liquid interaction properties: the liquid-philic layer is selectively positioned at the bottom center region to attract and concentrate semiconductor ink where adequate thickness is needed for transistor functionality, while the liquid-phobic bank walls prevent excessive ink accumulation at the inner edges, thus achieving balanced film thickness distribution
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 configuration ensures a semiconductor layer with a desirable cross-sectional shape, enhancing the properties and performance of the TFT by maintaining sufficient film thickness in the central area and reducing variations, thereby improving transistor functionality.
Implementation Method 1
a liquid-philic layer formed on a peripheral portion of an area of an upper surface of the substrate, and not overlapping a central portion of the area of the upper surface of the substrate
Implementation Method 2
the bank has a liquid-phobic lateral surface surrounding the aperture
Data Source
AI summary
An electronic device including: a substrate; a bank formed on an upper surface of the substrate, surrounding an area of the upper surface of the substrate, and defining an aperture from which the area is exposed; a liquid-philic layer formed on a peripheral portion of the area, and not overlapping a central portion of the area; a semiconductor layer formed within the aperture, and attaching to at least a portion of the central portion and to an upper surface of the liquid-philic layer; and a pair of electrodes that are in contact with an area of the semiconductor layer, the area of the semiconductor layer not overlapping the liquid-philic layer in plan view. The bank has a liquid-phobic lateral surface surrounding the aperture, and the upper surface of the liquid-philic layer has a higher degree of liquid-philicity than the upper surface of the substrate.