Vertical LED Device with Roughened Surface for Uniform Current
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Solution Overview
Problem
Conventional horizontal LED devices face issues with hot spots, non-uniform current density, and high fabrication costs due to the sapphire carrier lift-off process, which complicates the production of high-illumination LEDs with uniform current distribution.
Innovation Solution
A method for fabricating a vertical LED device using a n-type semiconductor substrate without a sapphire carrier, employing metal nano balls for a three-dimensional implantation process and chemical etching to roughen surfaces, eliminating the need for a lift-off process and enhancing light-emitting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sapphire carrier lift-off process is used in conventional LED fabrication, then the LED structure can be formed, but the fabrication cost increases and process complexity increases
Solution Approach 1:
The patent extracts and eliminates the sapphire carrier from the LED fabrication process. By growing the LED structure directly on a semiconductor substrate without requiring a sapphire carrier, the complex lift-off process is removed entirely, reducing both fabrication cost and process complexity while maintaining the ability to form the LED structure
Solution Approach 2:
The patent replaces the expensive and complex sapphire carrier system with a simpler, more cost-effective semiconductor substrate approach. The semiconductor substrate serves as a temporary growth platform that can be directly integrated into the final device, eliminating the need for costly sapphire carriers and their associated lift-off processes
2Ease of operation
If horizontal LED configuration is used with turned current path, then electrodes can be arranged on the same side, but hot spots and non-uniform current density occur
Solution Approach 1:
The patent inverts the conventional horizontal LED architecture by adopting a vertical configuration where the current flows perpendicular to the substrate surface rather than laterally. This inversion allows electrodes to be arranged on opposite sides while achieving uniform current density distribution, eliminating hot spots through the vertical current path
3Productivity
If substrate wafer is cut to fabricate individual LED chips, then individual chips can be produced, but the loss due to sawing process increases and total light-emitting area is reduced
Solution Approach 1:
The patent employs segmentation by forming individual LED chips through patterned growth regions on the semiconductor substrate. By using etch-stop layers and selective epitaxial growth, the substrate is divided into discrete chip regions that can be individually separated with minimal material loss, maintaining high total light-emitting area while enabling individual chip production
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 fabrication costs, improves light extraction efficiency, and increases the process window for etching, resulting in a more efficient and cost-effective vertical LED device with uniform current distribution.
Implementation Method 1
A current path can flow in and out of a semiconductor light-emitting layer of the vertical LED without turning in different directions
Implementation Method 2
A three-dimensional implantation process is performed using the first mask pattern and the plurality of metal nano balls collectively as a mask, so that a dopant is implanted into the first-type semiconductor substrate
Implementation Method 3
A three-dimensional implantation process is performed using the first mask pattern and the plurality of metal nano balls collectively as a mask
Data Source
AI summary
The invention provides a light-emitting diode device and a method for fabricating the same. The light-emitting diode device includes a metal substrate. A light-emitting diode structure is bonded on the metal substrate. The light-emitting diode structure includes a first type semiconductor substrate and a second type semiconductor layer. The first type semiconductor layer has a first surface and a second surface opposite to the first surface. The second type semiconductor layer is in contact with the metal substrate. A light-emitting layer is disposed between the first type semiconductor substrate and the second type semiconductor layer. A portion of the second surface and a sidewall adjacent to the second surface are uneven roughened surfaces.