GaN Substrate Self-Separation via Ion Implantation and Edge Grinding
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Solution Overview
Problem
Conventional methods for fabricating free-standing gallium nitride substrates are complex, hazardous due to hydrogen heat treatment, and limited by equipment design, making them costly and difficult to scale for high-quality, thick gallium nitride films with low dislocation density.
Innovation Solution
A method involving hydrogen ion implantation and edge grinding to form a separation layer, allowing self-separation of gallium nitride substrates using horizontal HVPE equipment without modifying existing equipment, and achieving a lower threading dislocation density and higher thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thick gallium nitride film is grown on a sapphire substrate, then the film thickness increases, but the stress between substrates increases leading to substrate breakage
Solution Approach 1:
The invention introduces a separation layer between the gallium nitride film and sapphire substrate, dividing the structure into distinct segments. This separation layer allows the thick gallium nitride film to be grown without direct mechanical stress transmission to the sapphire substrate, preventing breakage while maintaining film integrity.
Solution Approach 2:
The separation layer acts as an intermediary between the gallium nitride film and sapphire substrate. It mediates the stress relationship by providing a buffer zone that accommodates thermal expansion differences and prevents direct stress transmission, enabling thick film growth without substrate failure.
2Ease of manufacture
If a conventional hydrogen heat treatment process is used for self-separation, then the gallium nitride substrate can be separated, but the process becomes hazardous and complex
Solution Approach 1:
The invention replaces the chemical hydrogen heat treatment process with a mechanical/physical ion implantation process. By implanting ions during the growth stage, the separation function is achieved through physical means rather than hazardous chemical treatment, eliminating safety risks while maintaining self-separation capability.
Solution Approach 2:
The separation layer is formed preliminarily during the gallium nitride film growth process through ion implantation, rather than requiring subsequent hazardous heat treatment. This preliminary action embeds the separation function directly into the film structure, eliminating the need for dangerous post-growth processing.
3Ease of manufacture
If a Ti thin film and TiN nano-net are deposited and heat treated, then the gallium nitride membrane can be separated, but the process complexity increases and production costs rise
Solution Approach 1:
The invention extracts and eliminates the complex multi-step process of Ti thin film deposition, TiN nano-net formation, and heat treatment. By using ion implantation during growth, only the essential separation function is retained, removing unnecessary process steps and reducing overall fabrication complexity.
Solution Approach 2:
The invention merges the separation layer formation with the gallium nitride film growth process. By implanting ions during growth, the separation function is integrated into the primary fabrication step, eliminating the need for separate deposition and heat treatment processes.
4Ease of manufacture
If hydrogen ions are implanted at high concentration, then the separation layer forms more effectively, but crystal defects increase
Solution Approach 1:
The invention optimizes the ion implantation parameters, specifically controlling the concentration and energy of implanted ions. By adjusting these parameters to optimal values, the separation layer forms effectively while maintaining crystal quality, avoiding the trade-off between separation efficiency and defect formation.
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 gallium nitride substrates with significantly reduced crystal defects and enhanced thermal conductivity, suitable for high-brightness LEDs and semiconductor devices, while eliminating hazardous processes and equipment limitations.
Implementation Method 1
a step of implanting hydrogen ions into the first gallium nitride layer to form a separation layer
Implementation Method 2
a step of grinding edges of the substrate, the first gallium nitride layer, and the separation layer
Implementation Method 3
a step of self-separating the second gallium nitride layer from the first gallium nitride layer having a ground edge
Data Source
AI summary
The present invention relates to technology for fabricating a gallium nitride substrate using an ion implantation process to which a self-separation technique is applied. According to the present invention, a method of fabricating a gallium nitride substrate may include a step of forming a first gallium nitride layer on a substrate, a step of implanting hydrogen ions into the first gallium nitride layer to form a separation layer, a step of grinding the edges of the substrate, the first gallium nitride layer, and the separation layer, a step of forming a second gallium nitride layer on the first gallium nitride layer having a ground edge, and a step of self-separating the second gallium nitride layer from the first gallium nitride layer having a ground edge.