GaN Epitaxy on Insulating Substrates With Layer Splitting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing GaN epitaxy processes on insulating substrates face challenges such as vertical breakdown voltages and backgating issues, and require multiple bonding and separation steps that introduce defects into the epitaxial layer, affecting device performance and efficiency.
Innovation Solution
A method involving ion implantation and annealing to split epitaxial layers on a preliminary substrate, followed by chemical-mechanical polishing (CMP) to create seed and product wafers, reducing the number of bonding and debonding steps and minimizing defects, while using polycrystalline aluminum nitride (p-AlN) substrates for improved crystal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple bonding and separation steps are used to transfer epitaxial layers to insulating substrates, then the epitaxial layers can be placed on advantageous substrates, but defects are introduced into the epitaxial layer affecting device performance
Solution Approach 1:
The patent applies preliminary action by pre-forming the epitaxial AlGaN layers on a preliminary substrate with desirable crystal orientation and low dislocation density before transfer. This ensures the epitaxial layers are already optimized for device performance before being transferred to the insulating substrate, preventing defect introduction during the transfer process.
Solution Approach 2:
The patent uses an intermediary approach by employing a preliminary substrate as a mediator that temporarily holds the epitaxial layers during fabrication. This intermediary substrate allows the epitaxial layers to be grown under optimal conditions and then transferred to the final insulating substrate, separating the growth process from the transfer process to minimize defect introduction.
2Reliability
If epitaxial layers are transferred through multiple bonding and separation steps, then advantageous substrates can be used, but processing time increases
Solution Approach 1:
The patent performs preliminary action by completing the epitaxial layer growth and initial structuring on the preliminary substrate before transfer. This allows multiple devices to be fabricated on a single insulating substrate in one transfer operation, significantly reducing the total processing time compared to transferring layers individually or in smaller batches.
3Reliability
If thicker epitaxial layers are used to ensure adequate device functionality, then device performance is maintained, but deposition cost increases
Solution Approach 1:
The patent applies local quality by using a preliminary substrate with desirable crystal orientation and low dislocation density for growing the epitaxial layers. This high-quality substrate enables the growth of thinner epitaxial layers with sufficient crystal quality and low defect density to maintain device functionality, thereby reducing the amount of deposition material required while preserving device performance.
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 enhances GaN device performance by reducing dislocation densities and vertical breakdown voltages, allowing for multiple devices on a single semiconductor die and minimizing defects, thus improving yield and reducing processing time.
Implementation Method 1
Ions are implanted at a depth beneath the surface of the first layer
Implementation Method 2
Annealing is performed, such that the first epitaxial layer divides into a second epitaxial layer on the preliminary substrate and a third epitaxial layer on the seed insulating substrate
Implementation Method 3
The first layer's surface is polished... The third layer's surface is polished to obtain a seed wafer
Implementation Method 4
A method of epitaxial deposition includes depositing a first epitaxial layer of an aluminum gallium nitride (AlGaN) material onto a preliminary substrate
Data Source
AI summary
A semiconductor device includes a substrate, a dielectric layer on the substrate, a first epitaxial layer on the dielectric layer, and a second epitaxial layer on the first epitaxial layer.