Laser Ablation Patterning for Organic Electronic Devices
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Solution Overview
Problem
Current methods for patterning metallic conductive layers in organic electronic devices using laser ablation often result in significant thermal damage and degradation of underlying layers, particularly when using nanosecond lasers, which limits resolution and throughput, and causes issues like burring edges and electrical shorts.
Innovation Solution
A method employing a single pulse of a pulsed laser with controlled fluence and pulse duration to selectively remove the upper conductive layer without damaging the underlying layers, utilizing a dielectric stack for shielding and minimizing heat diffusion, and potentially combining with ultra-short pulse laser ablation for fine tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nanosecond laser ablation is used to pattern upper conductive layers, then material removal efficiency is improved, but thermal damage to underlying layers increases
Solution Approach 1:
The patent divides the laser pulse into multiple sub-pulses within the nanosecond duration, creating a multi-peaked pulse profile. This segmentation allows the laser energy to be delivered in controlled increments, removing material efficiently while preventing excessive heat accumulation that would damage underlying layers.
Solution Approach 2:
The patent employs periodic modulation of the laser pulse intensity, creating oscillating energy delivery patterns. This periodic action enables controlled material removal through repeated thermal cycling, achieving high efficiency while allowing heat dissipation between peaks to protect sensitive underlying structures.
2Productivity
If longer pulse duration is used for ablation, then material removal rate is improved, but heat-affected zone size increases
Solution Approach 1:
The patent dynamically changes the temporal profile parameters of the laser pulse, specifically creating a multi-peaked intensity distribution with varying durations and amplitudes. This parameter optimization allows extended pulse duration for higher removal rates while confining the heat-affected zone through controlled energy distribution in time.
3Productivity
If laser fluence is increased to improve ablation speed, then processing throughput is improved, but lateral thermal damage increases
Solution Approach 1:
The patent uses periodic intensity modulation with multiple peaks of varying fluence. Higher fluence peaks remove material rapidly for high throughput, while lower fluence peaks between them allow heat dissipation and prevent lateral thermal damage, achieving both high speed and precision.
4Manufacturing precision
If conventional laser ablation is used on multilayer structures, then upper layer patterning is achieved, but underlying layer degradation occurs
Solution Approach 1:
The patent segments the laser pulse into multiple controlled sub-pulses, allowing progressive material removal from the upper layer. This segmented approach enables precise patterning while limiting the cumulative thermal energy reaching underlying layers, preserving their integrity.
Solution Approach 2:
The patent incorporates lower fluence sub-pulses between high fluence ablation peaks, which act as cushioning intervals allowing heat dissipation. This beforehand cushioning prevents thermal energy from accumulating and degrading underlying layers while maintaining upper layer patterning quality.
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 high-resolution, high-throughput patterning of metallic layers with minimal degradation of underlying layers, achieving improved device performance by maintaining the integrity of sensitive materials and reducing thermal damage, thus enhancing the fabrication of organic electronic devices like TFTs and diodes.
Implementation Method 1
laser ablating using a pulsed laser to remove regions of upper conductive layer from underlying layer
Implementation Method 2
A route for achieving cost-effective electronics such as large area displays and RFID circuits at higher throughputs than are available using conventional inorganic semiconductor wafer processing is required within organic electronics
Implementation Method 3
utilizing a dielectric stack for shielding and minimizing heat diffusion
Implementation Method 4
This means that a process of ablation using nanosecond (ns) lasers is not as localised as that of shorter pulsed lasers. This often results in there being a considerable level of thermal damage around the ablation site (the heat-affected zone, HAZ)
Data Source
AI summary
A method of fabricating an organic electronic device is provided. The organic electronic device has a structure including an upper conductive layer and an underlying layer immediately beneath said upper conducting layer and having at least one solution process able semiconducting layer. The upper conducting layer preferably has a thickness of between 10 nm and 200 nm. The method includes 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.