Dual-Wavelength Laser Separation for Flexible Device Yield
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Solution Overview
Problem
The existing methods for separating layers in flexible device manufacturing, such as semiconductor and light-emitting devices, often result in high stress at the separation interface, leading to cracks and damage to the functional elements, thereby reducing the yield of the separation process.
Innovation Solution
A method involving the use of two types of laser light, where the first laser light is absorbed by the layer to be separated and the adhesive layer, and the second laser light is absorbed by the separation layer, to create a separation starting point and facilitate the separation process, improving the yield by reducing stress and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical force or single-laser ablation is used for separation, then separation can be achieved, but high stress is applied to the layer to be separated causing cracks and damage to functional elements
Solution Approach 1:
The separation process is divided into multiple stages using different laser wavelengths. The first laser (first wavelength) creates initial separation points and weakens bonds, while the second laser (second wavelength) completes the separation. This segmentation of the separation process reduces the stress applied at any single moment, preventing cracks in the functional layers.
Solution Approach 2:
The patent employs two different laser wavelengths with distinct absorption characteristics. The first wavelength is absorbed by the adhesive layer to initiate separation, while the second wavelength is absorbed by the separation layer to complete the process. By changing the parameter of laser wavelength, the stress is distributed and controlled, avoiding direct high-stress application to the functional elements.
2Productivity
If high stress is applied to achieve separation, then separation can be accomplished, but functional elements may be damaged
Solution Approach 1:
The patent introduces a separation layer as an intermediary between the substrate and the layer to be separated. This separation layer is specifically designed to absorb the second laser wavelength, facilitating separation while protecting the functional elements from direct stress. The intermediary layer acts as a buffer that enables efficient separation without compromising element integrity.
Solution Approach 2:
Before completing the separation, the first laser is used to create initial separation points and weaken the bonding between layers. This preliminary action reduces the overall stress required for final separation, thereby preventing damage to functional elements while maintaining separation efficiency.
3Ease of manufacture
If single-wavelength laser ablation is used, then the process is simple, but it cannot selectively target different layers for optimal separation
Solution Approach 1:
The patent applies different laser wavelengths to different layers based on their specific absorption properties. The first laser wavelength is selectively absorbed by the adhesive layer, while the second wavelength is selectively absorbed by the separation layer. This local quality approach—matching laser wavelength to specific layer properties—enables precise control of the separation interface while maintaining relative process simplicity.
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 enhances the yield of the separation process by reducing stress and preventing cracks in the functional elements, allowing for more efficient transfer of layers to flexible substrates, thereby improving the manufacturing efficiency of lightweight, thin, or flexible devices.
Implementation Method 1
In the first step, the first laser light is absorbed by at least the layer to be separated and the adhesive layer
Implementation Method 2
In the second step, the second laser light is absorbed by at least the separation layer
Implementation Method 3
The separation layer is ablated by laser irradiation, so that separation is generated in the separation layer
Data Source
AI summary
A starting point for separating a separation layer and a layer to be separated is formed in a process member. A first step of irradiating a first portion of the process member with first laser light in a frame-like shape and a second step of irradiating at least part of a region which is irradiated with the first laser light with second laser light are performed. The process member includes a first substrate, the separation layer, the layer to be separated, and an adhesive layer which are stacked in this order. In the first portion, the adhesive layer overlaps with the first substrate with the separation layer and the layer to be separated provided therebetween. In the first step, the first laser light is absorbed by at least the layer to be separated and the adhesive layer. In the second step, the second laser light is absorbed by at least the separation layer.