Encapsulated Micro-LED for Fluidic Assembly
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Solution Overview
Problem
Current micro-LED display technologies face challenges such as low efficiency, poor reliability, and high manufacturing costs due to the fragility of micro-LEDs during fluidic assembly, which results in damaged components and defects, especially for gallium nitride-based LEDs with thin epitaxial layers and non-circular shapes.
Innovation Solution
The use of partially encapsulated semiconductor-based inorganic micro-LEDs with a patternable polymer encapsulant that protects the LEDs from collisions and optimizes assembly, allowing for higher speed and yield by decoupling fluidic assembly from emissive element processing, and enabling shape-packaged micro-LEDs to promote self-assembly and alignment on a substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If micro-LEDs are used for direct emission display, then efficiency and dynamic range are improved, but reliability deteriorates due to fragility during fluidic assembly
Solution Approach 1:
The micro-LED assembly process is segmented into two independent stages: first, encapsulation of individual micro-LEDs in protective material; second, fluidic assembly of the encapsulated units. This segmentation protects the fragile micro-LEDs during handling while maintaining their light-emitting functionality.
Solution Approach 2:
The micro-LEDs are encapsulated in protective material before assembly, providing beforehand cushioning against mechanical damage during fluidic assembly. This pre-protection enables the fragile components to withstand the collisions and stresses of high-speed parallel assembly.
2Productivity
If massively parallel fluidic assembly is used, then productivity is improved, but manufacturing precision deteriorates due to component damage and defects
Solution Approach 1:
The micro-LEDs are pre-encapsulated in protective material before assembly, creating robust units that can withstand high-speed fluidic handling. This preliminary protection enables massively parallel assembly without sacrificing precision, as the encapsulated units resist damage during collisions and positioning.
Solution Approach 2:
The encapsulation material serves as an intermediary protective layer between the fragile micro-LED and the mechanical stresses of fluidic assembly. This mediator allows high-speed parallel processing while maintaining assembly precision by absorbing shocks and preventing direct contact damage.
3Reliability
If encapsulation material is added to protect micro-LEDs, then reliability is improved, but device complexity increases
Solution Approach 1:
The encapsulation is implemented as a thin protective film or shell around each micro-LED, providing reliability improvement with minimal added complexity. The thin-film approach protects the component without significantly increasing device size or structural complexity.
Solution Approach 2:
The encapsulation creates a composite structure combining the micro-LED core with a protective material shell. This composite approach enhances reliability while maintaining relatively simple device architecture, as the encapsulation layer integrates seamlessly with the assembly process.
Data Source
AI summary
A method is provided for fabricating an encapsulated emissive element. Beginning with a growth substrate, a plurality of emissive elements is formed. The growth substrate top surface is conformally coated with an encapsulation material. The encapsulation material may be photoresist, a polymer, a light reflective material, or a light absorbing material. The encapsulant is patterned to form fluidic assembly keys having a profile differing from the emissive element profiles. In one aspect, prior to separating the emissive elements from the handling substrate, a fluidic assembly keel or post is formed on each emissive element bottom surface. In one variation, the emissive elements have a horizontal profile. The fluidic assembly key has horizontal profile differing from the emissive element horizontal profile useful in selectively depositing different types of emissive elements during fluidic assembly. In another aspect, the emissive elements and fluidic assembly keys have differing vertical profiles useful in preventing detrapment.