Nitride Layer Laser Lift-Off Using SiC Buffer Thermal Management
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Solution Overview
Problem
Conventional methods for manufacturing nitride semiconductor devices using sapphire substrates face challenges due to poor thermal conductivity of sapphire, leading to heat-induced deterioration of the nitride layer during the laser lift off process, which degrades the physical and optical properties of the nitride layer.
Innovation Solution
A method involving the use of a buffer layer with higher thermal conductivity, such as SiC, to absorb and dissipate heat generated during the laser lift off process, where the intensity of the laser beam is adjusted to ensure decomposition occurs at the interface between the nitride and buffer layers, preventing heat-induced damage to the nitride layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sapphire substrate is used to grow a nitride layer, then the nitride layer can be formed on a substrate, but the poor thermal conductivity of sapphire causes heat-induced deterioration of the nitride layer during laser lift off
Solution Approach 1:
The patent introduces an artificial diamond layer as an intermediate thermal management layer between the sapphire substrate and the nitride layer. This intermediary layer has high thermal conductivity and serves to conduct heat away from the nitride layer during the laser lift off process, preventing heat-induced deterioration while allowing the sapphire substrate to remain as the growth substrate.
Solution Approach 2:
The patent changes the thermal conductivity parameter of the substrate system by introducing an artificial diamond layer with high thermal conductivity. This parameter change allows the system to handle the thermal load during laser lift off without deteriorating the nitride layer, resolving the contradiction between using sapphire as a substrate and avoiding heat damage.
2Ease of manufacture
If the laser beam intensity is increased to remove the nitride layer at the interface, then the lift off process becomes effective, but heat is transferred to the nitride layer causing deterioration
Solution Approach 1:
The artificial diamond layer acts as a thermal intermediary that allows the laser beam to effectively remove the nitride layer at the interface while preventing excessive heat transfer to the nitride layer. The high thermal conductivity of the diamond layer dissipates heat laterally, protecting the nitride layer from thermal damage during the lift off process.
Solution Approach 2:
The patent converts the harmful thermal energy that would otherwise damage the nitride layer into a beneficial thermal management mechanism. The artificial diamond layer utilizes the laser-induced heat to drive thermal conduction away from the nitride layer, transforming the potential harm into a protective thermal management function.
3Ease of manufacture
If the buffer layer is used as a sacrificial layer for separation, then the nitride layer can be separated from the sapphire substrate, but about 1000°C heat is transferred to the nitride layer causing deterioration
Solution Approach 1:
The artificial diamond layer serves as a thermal intermediary between the buffer layer and the nitride layer. During the laser lift off process, it mediates the thermal interaction by conducting heat away from the nitride layer, allowing the buffer layer to function as a sacrificial separation layer without transferring excessive heat to the nitride layer.
Solution Approach 2:
The artificial diamond layer provides beforehand thermal cushioning by being positioned between the heat source (buffer layer decomposition) and the nitride layer. This prior thermal management structure prevents the 1000°C heat transfer that would otherwise occur, protecting the nitride layer before the harmful thermal effect can manifest.
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 effectively prevents heat-induced deterioration of the nitride layer, allowing for the production of high-quality nitride layers and vertical nitride semiconductor light emitting devices with improved physical and optical properties.
Implementation Method 1
irradiating a laser beam to an underside of the sapphire substrate to remove the nitride layer
Implementation Method 2
decomposes the buffer layer 11, thus enabling separation of the nitride layer 12
Implementation Method 3
forming a buffer layer made of a material having a melting point and a thermal conductivity higher than those of nitride on the sapphire substrate
Data Source
AI summary
The present invention provides methods for manufacturing a nitride layer and a vertical nitride semiconductor light emitting device. In manufacturing the nitride layer according to the invention, a sapphire substrate is prepared. A buffer layer made of a material having a melting point and a thermal conductivity higher than those of nitride is formed on the sapphire substrate. Also, the nitride layer is formed on the buffer layer. Then a laser beam is irradiated to an underside of the sapphire substrate to remove the nitride layer. According to the invention, the nitride layer is made of a material having a composition expressed by AlxInyGa(1-x-y)N, where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1. In addition, the buffer layer is made of SiC.