LED Reflective Sidewall Structure for High Light Extraction
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face challenges in maintaining good optoelectronic characteristics and improving dicing yield as their size decreases, particularly in achieving sufficient reflectivity and light extraction efficiency due to the inclination of side surfaces in semiconductor stacks.
Innovation Solution
The implementation of an insulating reflective structure with alternating layers of different materials and thicknesses on both the main surface and side surface of the semiconductor stack, ensuring a high reflectivity of over 90% for the dominant or peak wavelength within an incident angle of 0° to 30°, which is achieved by carefully designing the thickness and material pairs to compensate for the inclination angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the light-emitting diode device is reduced, then the device becomes more compact and suitable for miniaturization applications, but the optoelectronic characteristics deteriorate and dicing yield decreases
Solution Approach 1:
The patent applies local quality by creating an insulating reflective structure with spatially varying thickness. The structure has a first thickness in the first region and a second thickness in the second region, allowing different areas to serve different functions: the first region provides baseline insulation while the second region with increased thickness provides enhanced light reflection and extraction efficiency, compensating for the reduced device size
Solution Approach 2:
The patent transitions from a uniform two-dimensional structure to a three-dimensional structure by introducing vertical thickness variation in the insulating reflective structure. This dimensional change allows the structure to provide both insulation and enhanced optical reflection functions within a compact footprint, addressing the optoelectronic performance degradation caused by miniaturization
2Ease of manufacture
If a conventional insulating structure is used, then the manufacturing process is simple, but the reflectivity and light extraction efficiency are insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the thickness parameter of the insulating reflective structure. By increasing the thickness in the second region compared to the first region, the structure achieves superior light reflection and extraction efficiency while maintaining manufacturing feasibility through a straightforward multi-layer deposition process
3Illumination intensity
If the thickness of the insulating reflective structure is increased, then the reflectivity improves, but the overall device thickness and manufacturing complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the insulating reflective structure into multiple regions with different thicknesses. The first region has a first thickness while the second region has a second thickness greater than the first thickness. This segmented approach allows the structure to achieve high reflectivity in specific areas without uniformly increasing the overall device thickness
Solution Approach 2:
The patent implements local quality by providing enhanced thickness only in the second region where improved reflection is needed, rather than uniformly increasing thickness across the entire structure. This localized thickening achieves high reflectivity while minimizing the overall device footprint and manufacturing complexity
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 design enhances the light-emitting diode's brightness and reflectivity, maintaining high efficiency even with variations in the inclination angle during manufacturing, while reducing the overall thickness and number of material pairs, thus lowering manufacturing costs and process time.
Implementation Method 1
The second part of the insulating reflective structure has a reflectivity of more than 90% for the dominant wavelength or the peak wavelength within an incident angle of 0° to 30°
Data Source
AI summary
A light-emitting device includes a semiconductor stack, an insulating reflective structure having an opening, and an electrode located on the insulating reflective structure and filled in the opening to electrically connect to the semiconductor stack. The semiconductor stack having includes a main surface, and a side surface inclined to the main surface. The light-emitting device has a dominant wavelength and a peak wavelength. The insulating reflective structure includes: a first part located on the main surface and having a first thickness; and a second part located on the side surface and having a second thickness different from the first thickness. The second part of the insulating reflective structure has a reflectivity of more than 90% for the dominant wavelength or the peak wavelength within an incident angle of 0° to 30°.