Semiconductor Light Emitting Device With Metal Substrate And Intermediate Layers
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Solution Overview
Problem
Existing semiconductor light emitting devices face challenges in reliability due to peeling issues during substrate bonding, primarily caused by mismatched thermal expansion coefficients and thermal conductivity between the metal substrate and the growth substrate, leading to potential mechanical damage and diffusion of metals.
Innovation Solution
A semiconductor light emitting device is designed with a metal substrate having a thermal expansion coefficient not exceeding 10×10−6 m/K and thermal conductivity of at least 160 W/m·K, utilizing a sintered impregnated metal with a surface roughness less than the thickness of the intermediate layer to prevent peeling and diffusion, and incorporating specific intermediate layers to enhance adhesion and thermal conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a metal substrate with high thermal conductivity is used for heat dissipation, then heat dissipation performance is improved, but thermal expansion mismatch causes peeling during bonding
Solution Approach 1:
An intermediate layer is introduced between the metal substrate and the nitride semiconductor layer to act as a mediator. This intermediate layer has thermal conductivity of 5-50 W/m·K, which is lower than the metal substrate (160 W/m·K or higher) but provides a gradual thermal transition. The intermediate layer's thermal expansion coefficient is matched to reduce stress, preventing peeling while maintaining effective heat dissipation through the substrate.
2Strength
If the surface roughness of the metal substrate is increased to improve adhesion, then bonding strength is improved, but metal diffusion to the intermediate layer is promoted
Solution Approach 1:
The surface roughness of the metal substrate is precisely controlled within the range of 0.01-10 μm. This parameter optimization provides sufficient adhesion strength through mechanical interlocking while preventing excessive roughness that would cause metal atoms to diffuse into the intermediate layer during bonding and operation. The controlled roughness ensures reliable bonding without promoting harmful metal diffusion.
3Reliability
If the thermal expansion coefficient of the substrate is reduced to match the nitride semiconductor, then peeling is suppressed, but heat dissipation capability is reduced
Solution Approach 1:
The thermal management path is segmented into multiple layers with different thermal properties. The metal substrate provides high thermal conductivity (160 W/m·K or higher) for efficient heat removal, while the intermediate layer provides thermal expansion matching (coefficient closer to nitride semiconductor) to prevent peeling. This segmentation allows each layer to optimize its function without compromising the other.
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 solution effectively suppresses peeling and maintains heat dissipation, resulting in a semiconductor light emitting device with improved reliability and extended lifespan by aligning thermal properties and preventing metal diffusion.
Implementation Method 1
a metal substrate, a stacked body, a first intermediate layer, and a second intermediate layer. The metal substrate has a coefficient of thermal expansion not more than 10×10−6 m/K... The thermal conductivity of the metal substrate is not less than 160 W/m·K
Implementation Method 2
The first intermediate layer is provided between the metal substrate and the second semiconductor layer to contact the metal substrate... incorporating specific intermediate layers to enhance adhesion and thermal conduction
Data Source
AI summary
According to one embodiment, a semiconductor light emitting device includes a metal substrate, a first semiconductor layer, a first semiconductor layer, a second semiconductor layer, a light emitting layer, a first intermediate layer and a second intermediate layer. The substrate has a coefficient of thermal expansion not more than 10×10−6 m/K. The first and second semiconductor layer include a nitride semiconductor. The second semiconductor layer is provided between the substrate and the first semiconductor layer. The emitting layer is provided between the first semiconductor layer and the second semiconductor layer. The first intermediate layer is provided between the substrate and the second semiconductor layer. The second intermediate layer is provided between the first intermediate layer and the second semiconductor layer. a surface roughness of a first surface of the substrate contacting the first intermediate layer is less than a thickness of the first intermediate layer.