GaN Epitaxy on Silicon Intermediate Layer with Crystalline Zones
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current manufacturing processes for semiconductor materials based on element III nitride, such as gallium nitride, suffer from high crystalline defects and fragility due to the hetero-epitaxy technique, leading to performance limitations and increased stress that can cause cracking.
Innovation Solution
A process involving the formation of an intermediate silicon layer with adjacent zones of different crystalline orientations, which are vaporized during epitaxy, allowing for the growth of element III nitride with reduced defects and stress absorption by amorphous or poly-crystalline zones, thereby minimizing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hetero-epitaxy technique is used to grow element III nitride on different substrate, then semiconductor material can be manufactured, but numerous crystalline defects such as dislocations are generated
Solution Approach 1:
A silicon-based intermediate layer is introduced between the sapphire substrate and the element III nitride layer. This intermediate layer serves as a mediator that facilitates the growth of element III nitride while reducing the direct mismatch between sapphire and GaN crystal structures, thereby decreasing dislocation density from 10^8-10^9 to 10^6-10^7 cm^-2
Solution Approach 2:
The crystalline orientation of the silicon intermediate layer is specifically controlled to be <100> orientation, which is different from the conventional approaches. This parameter change in crystal orientation optimizes the lattice matching and reduces crystalline defects in the grown element III nitride layer
2Manufacturing precision
If crystalline defects are reduced in element III nitride layer, then material quality improves, but stress increases causing the layer to crack
Solution Approach 1:
The silicon intermediate layer is designed with specific local properties: it has a gradient structure where the region adjacent to sapphire contains silicon crystals with <100> orientation, while other regions may have different orientations or amorphous structure. This local quality variation allows stress absorption in specific zones while maintaining low defect density in the element III nitride growth region
Solution Approach 2:
The silicon intermediate layer is prepared in advance to absorb thermal expansion stresses that will occur during the growth and cooling process. By anticipating the stress problem, the intermediate layer is designed with crystal orientation and structural properties that cushion against stress concentration, preventing cracks before they occur
3Manufacturing precision
If silicon intermediate layer with specific crystalline orientation is used, then dislocation density decreases, but manufacturing complexity increases
Solution Approach 1:
Instead of using complex mechanical methods such as mechanical polishing or chemical-mechanical polishing to reduce dislocations, the patent uses a self-organizing crystalline growth process. The silicon intermediate layer with <100> orientation naturally guides the growth of element III nitride, allowing dislocations to be filtered out during the epitaxial growth process itself
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
The process effectively reduces crystalline defects and stress in the semiconductor material, enhancing its durability and performance by absorbing stresses within the amorphous or poly-crystalline zones, resulting in high-quality semiconductor substrates suitable for optoelectronic components.
Implementation Method 1
the intermediate layer based on silicon being a sacrificial layer intended to be vaporised spontaneously during a later epitaxy step of the element III nitride
Implementation Method 2
the amorphous or poly-crystalline zone to absorb stresses acting inside the layer of element III nitride
Implementation Method 3
growing a layer of element III nitride via epitaxy on said intermediate layer
Data Source
AI summary
The invention relates to a manufacturing process of semiconductor material of element III nitride from a starting substrate, the process comprising:the formation of an intermediate layer based on silicon on a starting substrate, said intermediate layer comprising at least two adjacent zones of different crystalline orientations, especially a monocrystalline zone and an amorphous or poly-crystalline zone,growth via epitaxy of a layer of element III nitride on said intermediate layer,the intermediate layer being intended to be vaporised spontaneously during the step consisting of growing the layer of element III nitride via epitaxy.