Semiconductor Light Emitter Trench Passivation for Short-Free Bonding
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Solution Overview
Problem
Conventional semiconductor light emitting devices face issues with bonding material escaping during thermal compression, leading to poor electrical connections, reduced assembly rates, and lighting defects due to inadequate bonding and electrical shorts.
Innovation Solution
The semiconductor light emitting device features a light emitting unit with a first electrode on the bottom and sides, a second electrode on top, and a passivation layer positioned in trenches on the side, along with a connection electrode that maximizes contact area and prevents electrical shorts, ensuring stable attachment to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermal compression is applied to bond the light emitting device to the substrate, then bonding strength is improved, but bonding material escapes around the device causing electrical shorts
Solution Approach 1:
A bonding material retention structure is formed around the light emitting device before thermal compression bonding. This structure prevents bonding material from escaping during the subsequent thermal compression process, thereby eliminating electrical shorts while maintaining strong bonding between the device and substrate.
Solution Approach 2:
The bonding structure is segmented into distinct functional zones: a bonding region for thermal compression bonding, and a retention region with the bonding material retention structure that confines the bonding material. This segmentation allows the bonding material to be contained where needed while permitting effective thermal compression bonding.
2Ease of manufacture
If bonding material is provided on the lower side of the light emitting device, then bonding capability is improved, but bonding material escapes during heat compression reducing assembly reliability
Solution Approach 1:
The bonding material retention structure is preliminarily formed to counteract the harmful effect of bonding material escape during thermal compression. This structure ensures that the bonding material remains confined to the bonding region, maintaining both manufacturing ease and assembly reliability.
Solution Approach 2:
The bonding material retention structure acts as an intermediary element between the bonding material and the surrounding environment. It mediates the thermal compression process by allowing bonding material to be effectively applied while preventing its escape, thus ensuring reliable assembly.
3Manufacturing precision
If the light emitting device is made ultra-small for high resolution displays, then display resolution is improved, but alignment and transfer accuracy becomes more difficult
Solution Approach 1:
The light emitting device structure includes integrated features such as the bonding material retention structure and electrode configurations that enable self-alignment during the transfer process. This self-service mechanism allows ultra-small devices to be accurately positioned without requiring extremely precise external alignment tools or processes.
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 enhances light extraction efficiency, prevents electrical shorts, and improves brightness and reliability by ensuring uniform luminance and stable electrical connections between sub-pixels.
Implementation Method 1
the bonding layer provided on the lower part of the light emitting device is melted by thermal compression and is electrically connected to the electrical wiring of the substrate
Data Source
AI summary
The semiconductor light emitting device may include a light emitting unit, a first electrode on the bottom and side of the light emitting unit, and a second electrode on the top of the light emitting unit, a plurality of trenches on the sides of the light emitting unit, and a passivation layer on a side of the light emitting unit, and an end of the passivation layer may be located in one of the plurality of trenches.