Vertical GaN LED Mechanical Thinning with Stop Layer
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Solution Overview
Problem
Existing methods for manufacturing vertical GaN-based LEDs are inefficient due to inadequate laser lift-off processes and difficulties in differentiating between GaN layers, leading to unreliable and inefficient LED production.
Innovation Solution
A vertical GaN-based LED is fabricated using a conductive substrate with a p-type GaN layer, an active layer, an n-type GaN layer, and a highly doped stop layer, including an AlN/GaN superlattice structure, with stop points formed in the layers to facilitate mechanical thinning and selective etching, allowing for precise removal of the sapphire substrate and formation of an n-electrode on the highly doped stop layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser lift-off process is used to remove sapphire substrate, then substrate removal is achieved, but the process is inadequate and inefficient for manufacturing reliable LED
Solution Approach 1:
The patent extracts and removes the sapphire substrate through a controlled process that separates it from the GaN layers, allowing efficient substrate removal while preserving the integrity of the LED structure. The mechanical thinning process selectively removes the substrate without damaging the underlying GaN layers.
Solution Approach 2:
The patent replaces the laser lift-off process with a mechanical thinning process that uses controlled mechanical removal to eliminate the sapphire substrate. This substitution provides more reliable and efficient substrate removal while maintaining LED quality.
2Ease of manufacture
If traditional etching process is used on GaN layers, then layer removal is achieved, but it is difficult to differentiate the interface between different layers due to similar etching selectivity
Solution Approach 1:
The patent applies local quality by creating a highly doped stop layer with distinct properties (higher doping concentration, different material composition such as AlN/GaN superlattice) that provides unique etching characteristics. This localized modification allows precise identification and differentiation of layer interfaces during the etching process.
Solution Approach 2:
The highly doped stop layer acts as an intermediary layer between the n-type GaN layer and the active layer. It serves as a reference point and interface marker that facilitates precise differentiation during etching and mechanical thinning processes.
3Manufacturing precision
If stop layer with AlN/GaN superlattice structure is introduced, then layer differentiation and substrate removal precision are improved, but device structure complexity increases
Solution Approach 1:
The patent segments the n-type GaN layer by introducing a highly doped stop layer that divides the structure into distinct regions. This segmentation creates clearly defined interfaces and layers that are easier to process and differentiate, despite adding one more layer to the structure.
Solution Approach 2:
The patent uses composite materials by incorporating an AlN/GaN superlattice structure within the highly doped stop layer. This composite structure provides enhanced differentiation capabilities and precise substrate removal interfaces while maintaining overall structural integrity.
Data Source
AI summary
A vertical gallium-nitrate-based LED and method of making a vertical gallium-nitrate-based LED using a stop layer is provided. Embodiments of the present invention use mechanical thinning and a plurality of superhard stop points to remove epitaxial layers with a high level of certainty. According one embodiment, the method of making a vertical LED includes forming a plurality of layers on a sapphire substrate, forming a plurality of stop points in the plurality of layers, removing the sapphire substrate and part of a u-GaN layer using mechanical thinning, wherein the mechanical thinning stops at an end of the plurality of stop points, selectively etching the u-GaN layer and exposing at least a part of the highly doped stop layer, and forming an n-electrode on the highly doped stop layer.