Nitride Semiconductor Light Emitting Device Plated Metal Substrate
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Solution Overview
Problem
Existing semiconductor light emitting devices using nitride-based group III-V compound semiconductors face challenges with heat dissipation performance and light extraction efficiency, particularly due to issues with substrate bending, void formation, reduced adhesion force, and metal diffusion during thermo compression bonding and laser lift-off processes.
Innovation Solution
A semiconductor light emitting device is fabricated using a nitride-based III-V compound semiconductor with a plated metal layer as a support substrate, where a seed electrode layer covers the electrode layers to prevent metal diffusion, and isolation grooves are formed to facilitate laser lift-off, allowing for enhanced heat dissipation and reduced process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermo compression bonding is used to bond nitride-based group III-V compound semiconductor to heat dissipation substrate, then heat dissipation performance is improved, but substrate bending, void formation, and reduced adhesion force occur
Solution Approach 1:
A buffer layer is formed on the heat dissipation substrate before bonding the nitride-based group III-V compound semiconductor. This preliminary action prevents substrate bending and void formation during bonding, maintaining both heat dissipation performance and bonding reliability without requiring high-temperature thermo compression bonding.
Solution Approach 2:
The buffer layer acts as an intermediary between the heat dissipation substrate and the nitride-based semiconductor layer. It mediates the bonding process by providing a compliant interface that accommodates thermal expansion differences, preventing adhesion failure while enabling effective heat dissipation.
2Temperature
If laser lift-off method is used to peel off substrate, then heat dissipation performance is improved, but cracking of GaN thin film and support substrate occurs due to reduced adhesion force
Solution Approach 1:
The buffer layer is formed in advance on the heat dissipation substrate to establish a reliable bonding interface before the nitride-based semiconductor is bonded. This preliminary preparation ensures that the bonding strength is sufficient to withstand the mechanical stresses of laser lift-off, preventing GaN thin film cracking while achieving improved heat dissipation.
3Ease of manufacture
If thick metal film is formed by plating to use as substrate, then process steps and cost are reduced, but metal diffusion occurs
Solution Approach 1:
The buffer layer serves as an intermediary barrier between the plated metal film and the nitride-based group III-V compound semiconductor. It prevents metal diffusion into the semiconductor while allowing the plated metal to function as the heat dissipation substrate, combining manufacturing simplicity with compositional stability.
Solution Approach 2:
The invention replaces the conventional approach of using sapphire or SiC substrates with a plated metal substrate supported by a buffer layer. This substitution simplifies the manufacturing process and reduces cost while the buffer layer prevents the metal diffusion problem, enabling effective heat dissipation.
4Ease of manufacture
If sapphire substrate or SiC substrate is used, then crystal growth is feasible, but heat dissipation performance is insufficient
Solution Approach 1:
The substrate system is segmented into two functional components: a heat dissipation substrate (plated metal) and a buffer layer. The buffer layer provides the suitable interface for crystal growth of nitride-based semiconductors, while the plated metal substrate provides superior heat dissipation performance, separating these two functions for optimal performance.
Solution Approach 2:
The invention uses a composite structure combining a plated metal substrate with a buffer layer. This composite material system leverages the excellent heat dissipation properties of metal and the crystal growth compatibility of the buffer layer, achieving both ease of manufacture and superior heat dissipation performance.
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 improves heat dissipation and light extraction efficiency, reduces the risk of cracking and substrate peeling, and lowers fabrication costs by eliminating the need for thermo compression bonding, while maintaining mechanical strength and optical performance.
Implementation Method 1
heating, where the buffer layer has a function of absorbing an expansion stress generated by heating
Implementation Method 2
peeling off the substrate by a laser lift-off method
Data Source
AI summary
A semiconductor light emitting device has a light emitting element, a first electrode layer, a second electrode layer, a seed electrode layer and a plated layer. The light emitting element has a nitride-based III-V compound semiconductor on a substrate. The light emitting element having a light extraction surface. The first electrode layer on the light extraction surface. The second electrode layer is provided on a surface opposite to the light extraction surface of the light emitting element. The seed electrode layer is configured to cover the entire surface of the second electrode layer. The plated layer is provided on the seed electrode layer. The light emitting element has a light emitting layer, a first conductive type semiconductor layer, and a second conductive type semiconductor layer. The light emitting element has a forward tapered shape of a width which gradually narrows in order of the second conductive type semiconductor layer, the light emitting layer and the first conductive type semiconductor layer.