Micro-LED Electrode Layout to Reduce AlGaInP Dice Cracking
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Solution Overview
Problem
Existing micro-LED devices with AlGaInP-based LEDs face significant cracking issues during the laser lift-off (LLO) step due to mechanical fragility and mismatched electrode heights, which are not adequately addressed by prior arts.
Innovation Solution
A micro-LED device design where the light-emitting device structure surrounds the lower electrode, reducing level differences and stress concentration points, with a continuous or cutout configuration to minimize cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the lower electrode and upper electrode are formed separately in different batches, then the manufacturing process is simplified, but the electrode heights cannot match absolutely, causing stress concentration and dice cracking
Solution Approach 1:
The patent introduces a light-emitting device structure as an intermediary element that surrounds the lower electrode. This structure acts as a mediator to bridge the height difference between the separately formed lower and upper electrodes, distributing stress evenly and preventing concentration at the electrode interface, thereby avoiding dice cracking while maintaining the simplified separate formation process
2Ease of manufacture
If the base part connecting upper and lower electrodes is made from GaP material, then the light-emitting function is achieved, but the mechanical strength is extremely low due to high density of crystal dislocations
Solution Approach 1:
The patent segments the base part into two functional components: a light-emitting device structure made from GaP material that surrounds the lower electrode, and a connection structure that provides mechanical support. This segmentation allows the GaP material to fulfill its light-emitting function while the overall structure is designed to compensate for the low mechanical strength of GaP, distributing stress away from the vulnerable base part
3Device complexity
If one side of the lower electrode is not surrounded by the light-emitting device structure, then the manufacturing process is simpler, but the mechanical strength at the opening part is low and the structure is easy to cleave
Solution Approach 1:
The patent applies local quality by making the light-emitting device structure surround the lower electrode on all sides, creating a uniform protective enclosure. This complete surrounding structure provides consistent mechanical support and stress distribution at all critical points around the lower electrode, preventing cleavage that would occur at uncovered opening parts while maintaining manufacturing simplicity
Data Source
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AI summary
The present invention is a micro-LED device characterized by having one side less than 100 µm and a light-emitting device structure with an active layer included of (AlyGa1-y)xIn1-xP (0.4≤x≤0.6, 0≤y≤0.5) sandwiched between a first cladding and a second cladding; and having an upper electrode; and a lower electrode of opposite polarity to the upper electrode; and being a micro-LED device wherein the light-emitting device structure, the upper electrode, and the lower electrode are placed on a first surface of the micro-LED device; the upper electrode is placed on an upper surface of the light-emitting device structure; the lower electrode is placed in a location where the light-emitting device structure is not present; and the light-emitting device structure is placed so that it surrounds the lower electrode. This provides a micro-LED device that can reduce or avoid cracking of micro-LED devices (dices) that have one side less than 100 µm, and have an AlGaInP-based light-emitting device structure and two electrodes of opposite polarity on the same surface.