Semi-Polar GaN Layer Transfer via SMART-CUT Inversion
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Solution Overview
Problem
Existing methods for obtaining composite substrates with a layer of binary materials like GaN are costly and inefficient, requiring multiple operations and treatments to achieve the desired polar orientation, especially when transferring GaN layers from a donor substrate to a receiving substrate.
Innovation Solution
The method involves transferring a semi-polar or non-polar GaN layer using the SMART-CUT® technique, which includes implantation through the rear face of the donor substrate and bonding with a receiving substrate having a thermal expansion coefficient matching the GaN layer, reducing the need for costly treatments and operations by using a bonding interface such as SiO2 or metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the first known transfer method is used (picking up thin layer from rear N face), then the composite substrate can be obtained with Ga face orientation, but costly and complex rear face preparation treatments are required
Solution Approach 1:
The patent inverts the conventional approach by transferring the GaN layer from the front Ga face instead of the rear N face. This reversal eliminates the need for costly rear face preparation treatments while achieving the desired Ga face orientation on the composite substrate through a single transfer operation
2Ease of manufacture
If the second known transfer method is used (bonding front Ga face to intermediate substrate), then rear face treatment is avoided, but an intermediate substrate is required which burdens manufacturing cost
Solution Approach 1:
The patent extracts and eliminates the intermediate substrate step from the transfer process. By directly bonding the GaN layer from the front Ga face to the final receiving substrate, the method removes the unnecessary intermediate substrate that adds to device complexity and manufacturing cost
3Manufacturing precision
If multiple transfer operations are performed, then the desired Ga face orientation is achieved, but the number of operations increases which reduces productivity
Solution Approach 1:
The patent merges multiple transfer operations into a single direct transfer operation. By bonding the GaN layer directly from the front Ga face to the receiving substrate in one step, the method achieves the desired Ga face orientation while reducing the number of operations and improving productivity
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 simplifies the process of obtaining composite substrates with a desired Ga face orientation, reducing manufacturing costs and achieving high-quality epitaxial growth for electronic components like light-emitting diodes and laser diodes by minimizing thermal expansion coefficient differences between the substrate and the GaN layer.
Implementation Method 1
The transfer may notably be achieved by a method of the SMART-CUT® type... In this case, picking up the GaN layer involves implantation through the rear face of the donor substrate.
Implementation Method 2
bonding with a receiving substrate... by using a bonding interface such as SiO2 or metal layers
Data Source
AI summary
The present invention provides methods for fabricating a composite substrate including a supporting substrate and a layer of a binary or ternary material having a crystal form that is non-cubic and semi-polar or non-polar. The methods comprise transferring the layer of a binary or ternary material from a donor substrate to a receiving substrate.