Micro LED Chip Electrode Structure to Prevent Hollow Formation
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Solution Overview
Problem
The miniaturization of micro light-emitting diode (mLED) structures poses challenges, particularly in the multi-layer structure where different materials' etch selectivity can lead to hollow structures during processing, reducing yield and causing abnormalities.
Innovation Solution
A micro light-emitting chip structure with a dielectric structure featuring an annular sidewall with a variable inner diameter is introduced, which surrounds the electrode and reduces the likelihood of hollow structure formation by ensuring proper material deposition and etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is reduced to increase PPI, then image resolution is improved, but the design and fabrication complexity increases and yield decreases
Solution Approach 1:
The common electrode is divided into multiple segmented electrodes arranged in an array pattern. This segmentation allows for better control of etching processes in miniaturized structures, preventing hollow formation while maintaining high PPI. The segmented design enables independent optimization of each electrode region, reducing fabrication complexity despite high pixel density requirements.
Solution Approach 2:
The dielectric structure is designed with non-uniform thickness, being thicker at the bottom and thinner at the top, creating local quality variations that prevent hollow structure formation. This local thickness adjustment ensures proper material deposition and etching control in different regions of the miniaturized pixel structure, addressing fabrication challenges specific to high-PPI displays.
2Adaptability or versatility
If different materials are used in multi-layer structure, then functional performance is improved, but hollow structures form during etching due to etch selectivity
Solution Approach 1:
The dielectric structure acts as an intermediary element between the electrode and reflective layer. It provides a buffer zone that compensates for etch selectivity differences between materials, preventing hollow formation during the etching process. The dielectric material mediates the interaction between different layers, ensuring uniform material removal despite varying etch rates of adjacent materials.
Solution Approach 2:
The dielectric structure is formed in advance before the reflective layer, creating a pre-formed barrier that prevents hollow structure formation during subsequent etching processes. This preliminary action of depositing the dielectric layer with controlled thickness variation prepares the structure to withstand the etching of different materials without forming hollows.
3Ease of manufacture
If the dielectric structure has uniform thickness, then fabrication is simpler, but hollow structures are more likely to form
Solution Approach 1:
The dielectric structure employs non-uniform thickness distribution, being thicker at the bottom and thinner at the top, to locally prevent hollow structure formation. This local quality variation addresses the reliability issue by ensuring adequate material support where hollows are most likely to form, while maintaining fabrication feasibility through a controlled thickness gradient rather than completely complex variable geometry.
Data Source
AI summary
The micro light-emitting chip structure includes a first-type semiconductor layer, a light-emitting layer, and a second-type semiconductor layer that has an end surface. The micro light-emitting chip structure also includes a first insulating layer, a reflective layer, and a second insulating layer disposed on the second-type semiconductor layer. The micro light-emitting chip structure further includes an electrode and a dielectric structure. The electrode is disposed on the end surface and penetrates the second insulating layer, the reflective layer, and the first insulating layer. The dielectric structure is between the electrode and the reflective layer and surrounds the electrode. The annular sidewall of the dielectric structure has a first end away from the second-type semiconductor layer and a second end close to the second-type semiconductor layer. The inner diameter of the first end is greater than or equal to the inner diameter of the second end.