Picosecond Laser Ablation for Organic TFT Conductive Layers
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Solution Overview
Problem
Current methods for patterning metallic conductive pathways in organic electronic devices using laser ablation suffer from thermal damage, burring edge effects, and degradation of underlying layers, particularly when high-resolution and high-throughput processing is required on flexible substrates without high temperature processes.
Innovation Solution
A method employing a single pulsed laser pulse with controlled fluence and pulse duration to selectively remove the upper conductive layer, ensuring minimal degradation of underlying layers by using a self-limiting ablation process that shields the underlying layers from thermal damage and absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nanosecond laser ablation is used to pattern upper conductive layers, then throughput and resolution are improved, but thermal damage and degradation of underlying layers occur
Solution Approach 1:
The patent changes the laser pulse duration parameter from nanosecond to picosecond scale, which fundamentally alters the ablation mechanism. This parameter change enables high throughput patterning while minimizing thermal damage to underlying layers, as the ultrashort pulse duration prevents heat diffusion during the ablation process
Solution Approach 2:
The patent employs periodic pulsed laser action with picosecond duration, where the extremely short pulse width allows multiple pulses to be delivered in rapid succession without cumulative thermal damage. This periodic action maintains high productivity while protecting temperature-sensitive underlying layers
2Use of energy by moving object
If longer pulse duration lasers are used for ablation, then energy delivery is improved, but heat-affected zone and lateral damage increase
Solution Approach 1:
The patent changes the pulse duration parameter to picosecond scale, which fundamentally alters the energy delivery mechanism. The ultrashort pulse delivers sufficient energy for effective ablation while the extremely short duration prevents thermal diffusion, thereby minimizing the heat-affected zone and lateral damage
3Manufacturing precision
If conventional laser ablation is used on multilayer structures, then upper layer patterning is achieved, but underlying electroactive layers are degraded
Solution Approach 1:
The patent changes the laser pulse duration to picosecond scale, which enables precise upper layer patterning while protecting underlying electroactive layers. The ultrashort pulse duration ensures that energy is confined to the target layer during ablation, preventing thermal degradation of temperature-sensitive underlying layers
Solution Approach 2:
The patent uses periodic picosecond pulsed laser action to achieve precise patterning of upper conductive layers. The rapid pulse repetition rate allows efficient material removal while the ultrashort duration of each pulse prevents heat accumulation and protects the integrity of underlying electroactive layers
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 allows for high-resolution, high-throughput patterning of metallic conductive pathways in organic electronic devices without significant degradation of underlying layers, achieving high performance with improved conductivity and reduced contact resistance.
Implementation Method 1
laser ablating said upper conductive layer using a pulsed laser to remove regions of upper conductive layer from said underlying layer for said patterning; and wherein said laser ablating uses a single pulse of said laser to substantially completely remove a said region of said upper conductive layer
Data Source
Figure 1
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AI summary
The present invention relates to methods of fabricating electronic devices such as thin film transistor (TFT) structures using laser ablation for selective patterning. A method of fabricating an organic electronic device, said organic electronic device having a structure including an upper conductive layer and an underlying layer immediately beneath said upper conducting layer and having at least one solution processable semiconducting layer, said upper conducting layer preferably having a thickness of between 10 nm and 200 nm, the method comprising patterning said upper conductive layer of said structure by: laser ablating said upper conductive layer using a pulsed laser to remove regions of upper conductive layer from said underlying layer for said patterning; and wherein said laser ablating uses a single pulse of said laser to substantially completely remove a said region of said upper conductive layer to expose said underlying layer beneath.