Vertical LED Chip with Capacitor Structure for Heat Dissipation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High power LED devices with horizontal chip structures are prone to overheating and burnout due to poor heat dissipation and current crowding, while vertical chip structures face challenges with transient high-voltage pulses and electrostatic discharge (ESD).
Innovation Solution
A light-emitting diode (LED) chip design featuring a semiconductor epitaxial structure, an insulating substrate, and metal layers forming a capacitor structure to alleviate these issues, with the insulating substrate made of sapphire and metal layers on opposite surfaces to enhance heat dissipation and protect against ESD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a horizontal chip structure is used on a sapphire substrate, then the device can be manufactured with standard processes, but the heat dissipation is poor and current crowding occurs leading to overheating and burnout
Solution Approach 1:
The patent inverts the conventional horizontal chip structure to a vertical chip structure. The semiconductor epitaxial structure is grown vertically on the sapphire substrate with the light-emitting layer oriented perpendicular to the substrate surface. This vertical orientation fundamentally changes the heat dissipation pathway and current distribution, allowing heat to escape through the top surface while current spreads laterally through the vertical junction, eliminating the current crowding effect that plagues horizontal structures.
Solution Approach 2:
The invention transitions from a two-dimensional horizontal chip layout to a three-dimensional vertical structure. By growing the semiconductor epitaxial layers vertically with multiple quantum wells stacked along the growth direction, the patent adds a vertical dimension to both heat dissipation and current flow pathways. This dimensional change enables simultaneous improvement in heat management and current distribution that cannot be achieved with planar horizontal structures.
2Reliability
If a vertical chip structure is used, then heat dissipation and current distribution are improved, but the device becomes vulnerable to transient high-voltage pulses and electrostatic discharge (ESD)
Solution Approach 1:
The patent incorporates a capacitor structure consisting of first and second metal layers deposited on opposite surfaces of the sapphire substrate, with the substrate acting as the dielectric. This capacitor is integrated into the electrical circuit before ESD or high-voltage pulse events occur, providing preemptive protection. When transient voltage spikes or ESD events occur, the capacitor absorbs the energy surge, preventing it from reaching and damaging the vulnerable vertical LED chip structure.
3Power
If high current density is applied to achieve high power output, then brightness and power are improved, but overheating and burnout occur due to poor heat dissipation
Solution Approach 1:
By inverting the chip structure to vertical orientation, the patent reverses the conventional heat flow pattern. Instead of heat being generated in a planar junction and having to conduct laterally to edge contacts for dissipation, the vertical structure allows heat to conduct directly upward through the vertical junction to the top surface, providing a more efficient and direct thermal pathway that can handle high current density without excessive temperature rise.
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 heat dissipation and current spreading, enabling high current density applications while providing protection against transient high-voltage pulses and ESD, enhancing the durability and reliability of high power LED devices.
Implementation Method 1
a capacitor structure, comprising a first metal layer disposed on one of the two surfaces of the insulating substrate and a second metal layer disposed on the other one of the two surfaces of the insulating substrate
Implementation Method 2
the substrate thereof might be substituted with one made of a material with improved heat dissipation and thermal conductivity (e.g., Si, CuW, etc.)
Data Source
AI summary
A light-emitting diode (LED) chip includes a semiconductor epitaxial structure, an insulating substrate, a first metal layer, and a second metal layer. The semiconductor epitaxial structure includes a first semiconductor epitaxial layer, a second semiconductor epitaxial layer, and a light-emitting layer interposed between the first semiconductor epitaxial layer and the second semiconductor epitaxial layer. The insulating substrate has two opposite surfaces, and the first and second metal layers are respectively disposed on the two surfaces of the insulating substrate. An LED device and an LED lamp including the LED chip are also disclosed.