Group III Nitride Semiconductor Peeling via Al Droplet Buffer
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Solution Overview
Problem
Conventional methods for producing Group III nitride semiconductor devices face challenges in forming high-quality high temperature growth buffer layers and easily peeling off the semiconductor layer from the growth substrate, often resulting in poor crystallinity and complex processes due to the use of impurities like scandium and complicated substrate transfer procedures.
Innovation Solution
A method involving the formation of an Al layer or Al droplets on a substrate using an organic metal gas without ammonia, followed by the creation of an AlN buffer layer, allowing the Group III nitride semiconductor to be naturally peeled off when the substrate is removed from the vapor phase deposition apparatus, with controlled pressure and temperature conditions to ensure uniform deposition and maintain the Al layer in a molten state during semiconductor growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal buffer layer (e.g., scandium) is formed by sputtering and nitrided in MOCVD chamber, then the substrate can be peeled off, but the metal acts as impurity causing unexpected failure and the process becomes complicated with long cycle time
Solution Approach 1:
The patent removes the problematic metal buffer layer (scandium, chromium, hafnium, zirconium) from the process entirely. Instead, it uses a low-temperature grown AlN buffer layer that serves both as a growth buffer and enables easy substrate peeling without introducing impurities into the semiconductor layer.
Solution Approach 2:
The patent introduces a low-temperature grown AlN buffer layer as an intermediary between the sapphire substrate and the high-temperature grown Group III nitride semiconductor layer. This intermediary layer enables easy peeling while maintaining semiconductor quality, replacing the problematic metal buffer layer.
2Adaptability or versatility
If substrate is transferred from sputtering apparatus to MOCVD chamber, then metal buffer layer can be formed, but the process becomes complicated and cycle time increases
Solution Approach 1:
The patent combines the buffer layer formation and semiconductor layer formation processes into a single MOCVD chamber operation. The low-temperature AlN buffer layer is grown first, then the high-temperature Group III nitride semiconductor layer is grown on top without transferring the substrate to another apparatus, simplifying the overall process.
Solution Approach 2:
The MOCVD chamber is used for multiple purposes: first to grow the low-temperature AlN buffer layer, then to grow the high-temperature Group III nitride semiconductor layer. This multi-functional use of a single apparatus eliminates the need for substrate transfer between sputtering and MOCVD chambers.
3Manufacturing precision
If high temperature growth buffer layer is used, then good crystallinity is achieved, but it is not easy to form high quality buffer layer on growth substrate
Solution Approach 1:
The patent performs preliminary action by growing a low-temperature AlN buffer layer first, which prepares the substrate surface for subsequent high-temperature semiconductor layer growth. This preliminary low-temperature layer makes it easier to form the final high-quality high-temperature grown semiconductor layer with good crystallinity.
Solution Approach 2:
The patent uses parameter changes by growing the buffer layer at low temperature first, then changing to high temperature for the semiconductor layer growth. This temperature parameter change enables both easy buffer layer formation and high crystallinity in the final product.
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 results in a Group III nitride semiconductor with good crystallinity, simplified processing, and reduced risk of impurity contamination, enabling efficient and immediate formation of high-quality semiconductor devices with shorter cycle times and easy substrate peeling.
Implementation Method 1
forming an Al layer or Al droplets on a surface of a substrate by flowing an organic metal gas containing Al
Implementation Method 2
Voids may be formed in the Al layer or Al droplets by evaporating Al atoms from the Al layer or Al droplets
Implementation Method 3
When the Group III nitride semiconductor is grown on the AlN buffer layer, the Al layer or Al droplets may be kept in a molten state
Data Source
AI summary
The method comprises: forming an Al layer or Al droplets on a surface of a substrate by flowing an organic metal gas containing Al without flowing an ammonia gas; forming an AlN buffer layer on the Al layer or Al droplets by flowing the organic metal gas containing Al and the ammonia gas, the Al layer or Al droplets remaining as a metal under the AlN buffer layer; forming the Group III nitride semiconductor on the AlN buffer layer; and peeling the Group III nitride semiconductor in a place of the Al layer or Al droplets from the substrate.