Segmented LED Array Architecture to Prevent GaN Wafer Bowing
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Solution Overview
Problem
Manufacturing small addressable light-emitting diode (LED) arrays is costly and difficult due to the need for micron-level precision and the issue of wafer bowing caused by continuous GaN layers, which complicates high-temperature annealing and light extraction.
Innovation Solution
The use of selectively grown (SAG) and etched GaN mesas with trenches and isolation regions, along with a wavelength converting layer, to reduce stress and facilitate easier assembly and improved light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If continuous GaN layers are used in LED arrays, then light emission is achieved, but wafer bowing occurs which complicates high-temperature annealing and light extraction
Solution Approach 1:
The continuous GaN layer is segmented into isolated GaN mesas separated by trenches. This segmentation prevents wafer bowing while maintaining light emission capability, as each mesa acts as an independent light-emitting unit. The isolation regions between mesas eliminate the stress accumulation that causes bowing in continuous layers.
Solution Approach 2:
The problematic continuous GaN layer structure is extracted and replaced with discrete GaN mesas. By removing the continuous nature of the GaN layer and replacing it with isolated mesas surrounded by isolation regions, the wafer bowing issue is eliminated while preserving the essential light-emitting function.
2Manufacturing precision
If micron-level precision is required for small addressable LED arrays, then light emission quality improves, but manufacturing cost and difficulty increase
Solution Approach 1:
The GaN mesas are pre-formed with precise dimensions and positions before final assembly. The isolation regions are created beforehand to define the exact locations of individual LED elements. This preliminary structuring enables micron-level precision to be achieved more easily during manufacturing, as the critical dimensions are established in earlier fabrication steps rather than requiring ultra-precise final assembly.
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 approach reduces manufacturing costs and complexity, enhances light extraction efficiency, and allows for higher temperature annealing, resulting in improved brightness and precision control of LED arrays.
Implementation Method 1
a wavelength converting layer on the epitaxial layer between the first sidewall and the second sidewall
Data Source
AI summary
A device may include a metal contact between a first isolation region and a second isolation region on a first surface of an epitaxial layer. The device may include a first sidewall and a second sidewall on a second surface of the epitaxial layer distal to the first isolation region and the second isolation region. The device may include a wavelength converting layer on the epitaxial layer between the first sidewall and the second sidewall.