Laser Debonding of AlN Temporary Carriers for GaN Wafer Recovery
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Solution Overview
Problem
The use of silicon-based temporary carrier structures in semiconductor device fabrication leads to manufacturing defects such as cracking, dislocation, wafer bow, and warpage due to mismatched coefficients of thermal expansion with GaN materials, and the removal processes often damage the core layer, increasing costs and reducing yield.
Innovation Solution
A temporary carrier structure with a core layer of aluminum nitride and a debonding layer having a lesser bandgap lattice constant, where energy from a laser source is used to absorb and penetrate the debonding layer, reducing damage and enabling core layer reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silicon-based temporary carrier structures are used in GaN material fabrication, then the structural support and handling capability are improved, but manufacturing defects such as cracking, dislocation, wafer bow, and warpage occur due to mismatched coefficients of thermal expansion
Solution Approach 1:
The patent changes the material parameter of the temporary carrier structure from silicon to aluminum nitride, matching the coefficient of thermal expansion with GaN materials. This parameter change eliminates thermal expansion mismatch during fabrication processes, preventing cracking, dislocation, wafer bow, and warpage defects while maintaining structural support capability.
Solution Approach 2:
The patent employs a composite structure consisting of an aluminum nitride core layer bonded to a sacrificial layer. This composite design allows the aluminum nitride to provide thermal expansion matching and structural support, while the sacrificial layer enables controlled separation and core layer recovery without damaging the GaN device stack.
2Ease of manufacture
If traditional removal processes are used to separate the core layer from the temporary carrier structure, then the separation is achieved, but the core layer is damaged, increasing costs and reducing yield
Solution Approach 1:
The patent extracts the core layer from the temporary carrier structure through a controlled separation process. A sacrificial layer is introduced between the aluminum nitride core and the GaN device stack, allowing the core layer to be removed cleanly without damaging the device or the core itself, enabling recovery and reuse.
Solution Approach 2:
The patent introduces a sacrificial layer as an intermediary between the aluminum nitride core layer and the GaN device stack. This intermediary layer facilitates clean separation by being selectively removable, allowing the core layer to be extracted intact for reuse while leaving the device stack undamaged.
3Manufacturing precision
If aluminum nitride core layer is used instead of silicon, then thermal expansion matching with GaN materials is improved, but the cost and complexity of the temporary carrier structure increases
Solution Approach 1:
The patent segments the temporary carrier structure into distinct functional layers: an aluminum nitride core layer for thermal expansion matching and structural support, and a sacrificial layer for controlled separation. This segmentation allows each layer to perform its specific function efficiently, with the sacrificial layer enabling core recovery that offsets the initial complexity investment.
Solution Approach 2:
The patent implements a recoverable core layer system where the aluminum nitride core is preserved through the fabrication process and then recovered after device completion. The sacrificial layer is discarded during separation, but the valuable aluminum nitride core and GaN device stack are both recovered intact, reducing overall manufacturing costs through core reuse.
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 minimizes manufacturing defects and increases the yield of semiconductor devices by matching thermal expansion coefficients and allowing for the recovery of the core layer, thereby reducing resource consumption and manufacturing costs.
Implementation Method 1
providing energy from a laser source to a debonding layer that is between a core layer of the first temporary carrier structure and a seed layer held by the first temporary carrier structure
Data Source
AI summary
Some implementations described herein provide a temporary carrier structure and techniques to form a semiconductor device on the temporary carrier structure. The temporary carrier structure includes a core layer formed from a material having a first bandgap lattice constant. The temporary carrier structure further includes a debonding layer formed from another material having a second bandgap energy constant that is lesser relative to the first bandgap lattice constant. Techniques to form the semiconductor device including a forming substrate layer of the semiconductor device on the temporary carrier structure, where a material of the substrate layer and the material of the core layer have a same approximate coefficient of thermal expansion. The techniques further include providing energy (e.g., electromagnetic waves from a laser source) to the debonding layer to remove the core layer from the temporary carrier structure.