GaN Vertical Laser Chip Packaging With Epitaxial Layer Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge lies in fabricating high-quality semiconductor devices, particularly laser diodes and white light sources, using gallium nitride (GaN) materials, which require low defect-density and high crystal quality epitaxial structures, but are hindered by the difficulty in synthesizing GaN single crystal substrates and the high cost and limited availability of native GaN substrates, making it economically unfeasible for large-scale applications.
Innovation Solution
A method involving epitaxial deposition on native GaN substrates followed by selective etching and transfer to larger carrier wafers, allowing for the reuse of substrates and die expansion, enabling the fabrication of high-quality GaN-based devices on more mature substrate technologies like silicon and sapphire, thereby reducing costs and overcoming the limitations of small GaN wafer sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial deposition is performed on native GaN substrates to achieve high crystal quality and low defect density, then the quality of GaN semiconductor devices is improved, but the cost increases and scalability is limited due to small wafer sizes
Solution Approach 1:
The patent divides the expensive native GaN substrate into smaller reusable substrates through selective etching and release processes. The epitaxial layers are segmented from the original large substrate and transferred to multiple smaller carrier substrates, allowing one large substrate to serve multiple device fabrication cycles.
Solution Approach 2:
The patent recovers and reuses the expensive native GaN substrates by selectively removing sacrificial layers through etching processes. After the epitaxial layers are transferred to carrier substrates, the original substrates can be cleaned and reused for subsequent epitaxial growth, significantly reducing material costs.
2Reliability
If epitaxial deposition is performed on native GaN substrates to achieve low defect density, then device performance is improved, but the substrate cost becomes prohibitively high for large-scale applications
Solution Approach 1:
The patent implements a substrate recovery system where expensive native GaN substrates are reused multiple times. The sacrificial layers are selectively etched away, allowing the epitaxial layers to be released and transferred to carrier substrates, while the original substrates are recovered for reuse in subsequent fabrication batches.
Solution Approach 2:
The patent creates copies of the high-quality epitaxial structures on cheaper carrier substrates. The critical device layers are replicated from the native substrate to multiple carrier substrates, allowing the expensive substrate to serve as a master template that can produce many device copies on economical substrates.
3Ease of manufacture
If heteroepitaxy is performed on foreign substrates like sapphire or SiC to reduce substrate cost, then manufacturing cost is reduced, but defect density increases due to strain-related defects
Solution Approach 1:
The patent uses a sacrificial intermediate layer (such as AlN or AlGaN) grown on the foreign substrate that serves as a mediator. This intermediate layer is subsequently selectively removed through etching, allowing the device layers to be released and transferred to carrier substrates, thereby eliminating the defect-prone foreign substrate interface from the final device structure.
Solution Approach 2:
The patent extracts and removes the problematic foreign substrate and sacrificial intermediate layers through selective etching processes. The harmful substrate-material interface is completely taken out of the final device structure, leaving only the high-quality device layers on the carrier substrate.
4Manufacturing precision
If GaN substrates are grown in small diameters (2-4 inches) to maintain quality, then crystal quality is maintained, but wafer area and production volume are limited
Solution Approach 1:
The patent segments the limited-area native substrate into multiple smaller reusable substrates. Through selective etching and release, the epitaxial layers are divided and transferred to multiple carrier substrates, effectively multiplying the usable area from a single native substrate and enabling higher production volumes.
Solution Approach 2:
The patent transitions from a single large-area substrate approach to a multi-substrate three-dimensional arrangement. By stacking and arranging multiple smaller carrier substrates with transferred epitaxial layers, the system achieves equivalent or greater total device area while maintaining the quality benefits of small native substrates.
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 enables the production of high-quality GaN semiconductor devices with reduced substrate consumption, allowing for larger wafer processing and reuse, thus achieving cost-effective and scalable fabrication of GaN-based laser diodes and LEDs, and enabling the use of nonpolar and semipolar substrates in commercial applications.
Implementation Method 1
epitaxial deposition on native GaN substrates
Implementation Method 2
selective etching and transfer
Data Source
AI summary
Horizontal Cavity Surface Emitting Lasers (HCSELs) with angled facets may be fabricated by a chemical or physical etching process, and the epitaxially grown semiconductor device layers may be transferred through a selective etch and release process from their original epitaxial substrate to a carrier wafer.