Gallium Nitride Substrate Multi-Ion Implantation
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Solution Overview
Problem
The existing methods for fabricating gallium nitride substrates face challenges such as bowing and cracking, which affect the quality and yield of the substrates, and involve high production costs due to damage to the crystalline GaN bulk and the inability to recycle it, leading to increased costs and compromised mechanical strength of thin films.
Innovation Solution
A method involving first and second ion implantation processes to form damaged and blister layers, respectively, on the gallium nitride substrate, allowing for bonding to a temporary substrate, separation, and growth of a seed layer to form bulk gallium nitride, with controlled thickness and heat treatment to prevent bowing and cracking, and enhance substrate quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of GaN films is reduced to obtain a larger number of GaN substrates, then productivity increases, but mechanical strength decreases making self-supporting substrates impossible
Solution Approach 1:
The patent introduces an intermediary substrate (such as sapphire, SiC, or Si) that provides mechanical support to the thin GaN film. The thin GaN film is grown on this substrate, which acts as a mediator to enable the film to achieve self-supporting strength without requiring excessive thickness, thus allowing production of multiple substrates while maintaining mechanical integrity.
2Strength
If conventional ion implantation is used to bond GaN thin film to a different substrate, then mechanical strength is improved, but crystal damage occurs causing bowing and increasing production costs
Solution Approach 1:
The patent uses a template substrate with a specific crystal structure (such as sapphire or SiC) that serves as a model for growing the GaN layer. By epitaxially growing GaN on this template, the crystal structure is copied and transferred, enabling the formation of high-quality GaN films with reduced defects and minimal bowing, while maintaining mechanical strength through the substrate support.
3Shape
If hydrogen ions are implanted into both sides of GaN substrate to reduce bow, then substrate flatness is improved, but multiple layers are damaged and quality deteriorates
Solution Approach 1:
The patent applies local quality by performing ion implantation only on specific regions or surfaces of the GaN substrate rather than uniformly treating both sides. This selective implantation allows for localized stress management and bow correction while preserving the crystal quality in other regions, avoiding the damage that would result from treating the entire substrate.
4Ease of manufacture
If crystalline GaN bulk is damaged to form a bonded substrate, then ease of manufacture is improved, but the bulk cannot be recycled leading to increased costs
Solution Approach 1:
The patent employs a growth-substrate separation approach where the GaN layer is grown on a temporary substrate and then separated. The temporary substrate can be reused for subsequent growth cycles, while the GaN layer is recovered as the final product. This method allows the valuable GaN bulk material to be recovered and reused, reducing waste and production costs while maintaining ease of manufacture.
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 results in a gallium nitride substrate with high quality and low defect density, addressing bowing and cracking issues while reducing production costs by enabling the reuse of GaN bulk and improving mechanical strength.
Implementation Method 1
performing first ion implantation for a surface of the first gallium nitride, on which the bonding oxide film is formed, at least once to form a damaged layer, thereby releasing bow of the first gallium nitride
Implementation Method 2
performing second ion implantation for the surface of the first gallium nitride, on which the bonding oxide film is formed, to form a blister layer
Implementation Method 3
the method exhibited a problem that a process is complicated because thermal annealing is performed after ion implantation
Data Source
AI summary
Disclosed is a method of fabricating a gallium nitride substrate using a plurality of ion implantation processes. A method of fabricating a gallium nitride substrate using a plurality of ion implantation processes according to an embodiment of the present disclosure includes a step of forming a bonding oxide film on the first gallium nitride; a step of performing first ion implantation for a surface of the first gallium nitride, on which the bonding oxide film is formed, at least once to form a damaged layer, thereby releasing bowing of the first gallium nitride; a step of performing second ion implantation for the surface of the first gallium nitride, on which the bonding oxide film is formed, to form a blister layer; a step of bonding the bonding oxide film of the first gallium nitride to a temporary substrate; a step of separating the first gallium nitride using the blister layer to form a seed layer; and a step of allowing growth of the second gallium nitride using the seed layer to form bulk gallium nitride.