LED Submount Recess with Arc-Shaped Sidewall for Light Extraction
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Solution Overview
Problem
LEDs suffer from light loss and reduced light-emitting efficiency due to photons being trapped within the package structure, limiting their luminance and application potential.
Innovation Solution
A silicon submount with a recess having an arc-shaped sidewall is fabricated using a thermal oxidation process and LOCOS technology, allowing for the formation of a recess without lattice direction constraints, and optionally enhanced with ion implantation to create a reflective layer for improved light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional LED packaging structure is used, then manufacturing process is simple, but light loss occurs and light-emitting efficiency is reduced
Solution Approach 1:
The patent applies curvature by forming an arc-shaped sidewall in the recess of the submount structure. This curved geometry is achieved through a multi-step fabrication process involving mask formation, thermal oxidation to create a silicon oxide layer, and selective removal. The arc-shaped sidewall enables photons to escape more effectively by reducing total internal reflection compared to flat surfaces, thereby reducing light loss while maintaining a relatively simple overall package structure.
Solution Approach 2:
The patent implements local quality by creating a recess with arc-shaped sidewall in a specific localized region of the submount, rather than changing the entire package structure. This localized geometric modification is achieved through selective mask formation and oxidation processes that affect only the targeted area, allowing photons to escape efficiently from this specific region while keeping the rest of the package structure simple and manufacturable.
2Productivity
If recess with arc-shaped sidewall is formed, then light extraction efficiency is improved, but fabrication process complexity increases
Solution Approach 1:
The patent applies preliminary action by first forming a mask layer pattern and then performing thermal oxidation to create a silicon oxide layer before final recess formation. This sequence of preliminary steps prepares the structure in advance, allowing the arc-shaped sidewall to be created systematically through controlled oxidation and removal processes, thereby achieving high light extraction efficiency through a structured fabrication approach.
Solution Approach 2:
The fabrication process is segmented into distinct steps: mask formation, thermal oxidation to create silicon oxide layer, selective removal of the oxide layer, and final recess formation. This segmentation of the fabrication process into manageable stages allows for precise control of the arc-shaped sidewall geometry while maintaining overall process feasibility, balancing light extraction efficiency with manufacturing complexity.
3Illumination intensity
If photons are completely radiated to outside, then light-emitting efficiency is maximized, but this cannot be achieved in practice due to loss mechanisms
Solution Approach 1:
The arc-shaped sidewall with curved geometry modifies the optical path of photons generated in the LED chip. The curvature creates varying incident angles for photons striking the sidewall, reducing the occurrence of total internal reflection and enabling more photons to escape. This geometric modification directly addresses photon loss by transforming the radiation pattern, thereby increasing light-emitting luminance and efficiency.
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 approach enhances light-emitting luminance and efficiency by reducing light loss and allowing for adjustable light shape, improving the LED's performance and versatility in packaging.
Implementation Method 1
forming a first silicon oxide layer in the part of the silicon substrate which is exposed; and removing the mask layer and the first silicon oxide layer, so as to form a recess in the silicon substrate
Implementation Method 2
performing an ion implantation process to form a plurality of implantation regions in a part of the sidewall of the recess
Data Source
AI summary
A submount for a light emitting diode and a method for fabricating the same are provided. The method includes the following steps: (a) providing a silicon substrate; (b) forming a mask layer on the silicon substrate to expose a part of the silicon substrate; (c) forming a first silicon oxide layer in the part of the silicon substrate which is exposed; and (d) removing the mask layer and the first silicon oxide layer, so as to form a recess in the silicon substrate.