Vertical LED Chip Recess Structure for Heat and Current Spreading
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Solution Overview
Problem
High-power LEDs in horizontal structures face overheating and current-crowding issues due to poor heat dissipation, limiting their current density and brightness, while vertical structures with better heat dissipation materials can handle high current densities but require improved current spread and reliability.
Innovation Solution
A light-emitting diode chip design featuring a semiconductor layer sequence with recesses covered by an insulating layer, where conduction layers are insulated from each other and directly connected to a heat-dissipation base, facilitating uniform current distribution and enhanced heat management through a recess structure that extends from the back side to the front side, allowing for higher current density and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If horizontal structure with sapphire substrate is adopted, then current density is limited, but heat dissipation is poor causing overheating and chip burnout
Solution Approach 1:
The patent inverts the conventional horizontal LED structure to a vertical structure, where the current flows vertically through the semiconductor layers from bottom to top. This inversion allows the use of highly thermally conductive substrates like CuW (copper tungsten) or SiC (silicon carbide) at the bottom, which efficiently conduct heat away from the active region, solving the heat dissipation problem while enabling high current density operation.
Solution Approach 2:
The patent changes the substrate material parameters from sapphire (low thermal conductivity) to CuW or SiC (high thermal conductivity), and modifies the structural orientation from horizontal to vertical. These parameter changes enable the LED to operate at ultra-high current densities (2.5 A/mm² or above) by improving heat dissipation capability and eliminating current-crowding effects.
2Temperature
If vertical structure with high thermal conductivity substrate is adopted, then heat dissipation is improved, but current spread and reliability need further improvement
Solution Approach 1:
The patent applies local quality by creating a current spreading layer with specific material composition and doping characteristics between the substrate and the active region. This layer is locally optimized to provide uniform current distribution across the active area, preventing current crowding at the edges while maintaining efficient heat dissipation through the vertical structure.
Solution Approach 2:
The patent introduces a current spreading layer that extends laterally in another dimension, creating a gradient in electrical properties that guides current flow uniformly across the active region. This dimensional approach to current management enhances reliability by ensuring even current distribution while preserving the vertical heat dissipation pathway.
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 design improves the reliability and efficiency of high-power LEDs by ensuring uniform current distribution and effective heat dissipation, enabling higher current densities and brightness while maintaining chip reliability under high voltage conditions.
Implementation Method 1
an active layer located between the first-type semiconductor layer and the second-type semiconductor layer and configured to generate radiation
Implementation Method 2
a base for support and heat-dissipation
Data Source
AI summary
Disclosed is a light-emitting diode chip. A first electrode and a second electrode of the light-emitting diode chip face towards a front side. A back side of a first conduction layer is directly connected to a front side of a base. A portion of the first conduction layer is at least exposed from the front side to be used for the arrangement of the first electrode. A portion of a second conduction layer is at least exposed from the front side to be used for the arrangement of the second electrode. The exposed first conduction layer and the exposed second conduction layer are of equal height. An insulating layer extending from a recess covers a back side of the second conductive layer.