LED Chip Electrode Structure for DBR Through-Hole Continuity
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Solution Overview
Problem
Conventional flip light-emitting diode chips face issues with electrode discontinuity and fractures due to the formation of through holes in the DBR layer, which affect the reliability and efficiency of the chip.
Innovation Solution
The design includes an insulating layer with through holes and hole-defining walls that extend beyond the electrode surface, ensuring the electrodes are fully covered and avoiding fractures, and uses a DBR layer with specific materials and thickness to enhance reflectance and luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If through holes are formed in the DBR layer to expose electrodes, then electrode accessibility is improved, but electrode discontinuity and fractures occur reducing reliability
Solution Approach 1:
The patent transitions from a planar hole configuration to a three-dimensional protruding structure. The hole-defining wall extends upward from the DBR layer surface, creating a vertical dimension that allows the electrode to wrap around and connect continuously. This dimensional change eliminates the discontinuity problem while maintaining accessibility.
Solution Approach 2:
The hole-defining wall is formed in advance during the DBR layer formation process, before electrode deposition. This preliminary structure preparation ensures that the electrode can be deposited continuously over the protruding wall, preventing fractures that would occur if the hole structure were created after electrode formation.
2Loss of energy
If DBR layer thickness is increased to improve reflectance, then luminous efficiency is improved, but manufacturing complexity and difficulty increase
Solution Approach 1:
Instead of uniformly increasing DBR layer thickness throughout, the patent applies the DBR layer selectively in specific regions. The DBR layer is formed on the light-emitting unit and extends to create the hole-defining wall, but not necessarily across the entire chip area. This localized application maintains high reflectance where needed while reducing overall manufacturing complexity.
Solution Approach 2:
The DBR layer is segmented into functional regions: a base layer on the light-emitting unit for reflectance, and an extended portion forming the hole-defining wall for structural and electrical functions. This segmentation allows optimization of thickness in different regions - thicker where reflectance is needed, thinner or absent where only structural support is required.
3Ease of manufacture
If conventional hole formation is used in DBR layer, then manufacturing process is simple, but electrode fractures reduce yield
Solution Approach 1:
The hole-defining wall structure is created as a preliminary feature during the DBR layer formation process, before electrode deposition begins. This advance preparation ensures that the electrode can be deposited in a single continuous operation over the protruding wall, eliminating the need for complex multi-step electrode formation processes while ensuring high precision and continuity.
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
The solution improves electrode continuity, reduces fractures, and enhances the reliability and luminous efficiency of the light-emitting diode chip by optimizing the electrode formation process.
Implementation Method 1
The DBR is formed as a multilayered structure and includes different dielectric layers that are alternately stacked on one another. Light transmitted into the DBR may undergo a near total reflection in a certain frequency range.
Implementation Method 2
The reflection layer may be made of a metal having a high reflectance (e.g., silver and aluminum), non-metallic material (e.g., distributed Bragg reflection (DBR)) and a combination thereof.
Data Source
AI summary
A light-emitting diode chip includes a light-emitting unit, a first electrode, an insulating layer, and a second electrode. The first electrode is disposed on the light-emitting unit. The insulating layer is disposed on the first electrode and the light-emitting unit, and has a through hole and a hole-defining wall. The hole-defining wall has a top peripheral edge that has two opposite end points. A projection of at least one of the end points of the top peripheral edge on the light-emitting unit falls outside a projection of a top surface of the first electrode on the light-emitting unit. The second electrode is disposed on the insulating layer and fills the through hole to electrically connect to the first electrode.