Low-Oxygen Gallium Nitride Sintered Body for Stable Sputtering
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Solution Overview
Problem
Existing methods for forming gallium nitride thin films face challenges such as low productivity, high cost, inclusion of oxygen impurities, and difficulty in achieving large-sized, homogeneous, and highly crystalline films, particularly when using metal gallium targets or sputtering methods, which also require expensive equipment and complex processes.
Innovation Solution
A large-sized gallium nitride-based sintered body with low oxygen content and high strength is produced by treating gallium nitride powder with a hot press mold, using specific impurity levels and thermal expansion coefficients to ensure high crystallinity and stability, allowing for the formation of n-type or p-type semiconductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal gallium target is used for sputtering, then the sputtering process can be conducted, but the target melts during sputtering due to low melting point (29.8°C), making it difficult to obtain stable gallium nitride films
Solution Approach 1:
The patent changes the physical state parameter of gallium from liquid/metal form to solid ceramic form (gallium nitride). By converting gallium into gallium nitride compound, the melting point is dramatically increased, allowing the target to maintain structural stability during sputtering while still enabling the deposition of gallium nitride films.
Solution Approach 2:
The patent uses gallium nitride as a composite target material that combines gallium with nitrogen in a stable ceramic structure. This composite approach allows the target to provide both the gallium source for film deposition and the structural stability needed for high-power sputtering, eliminating the melting problem of pure metal gallium.
2Reliability
If cooling devices are installed to prevent target melting, then target stability is improved, but productivity decreases and oxygen inclusion in the film increases
Solution Approach 1:
The patent fundamentally changes the thermal parameter of the target material by using gallium nitride instead of metal gallium. This eliminates the need for active cooling systems while maintaining target stability, thereby restoring full productivity and avoiding oxygen contamination associated with cooling device operation.
3Manufacturing precision
If high pressure (58 Kbar) is applied to densify the sintered body, then density is improved, but the apparatus becomes very expensive and large-sized sintered bodies cannot be prepared
Solution Approach 1:
The patent changes the pressure parameter from extremely high pressure (58 Kbar) to moderate pressure levels achievable with conventional sintering equipment. By optimizing the sintering process at lower pressures, the patent achieves sufficient density without requiring expensive, complex high-pressure apparatus, thereby enabling large-sized sintered body production.
4Manufacturing precision
If nitriding is performed to reduce oxygen content, then oxygen amount is decreased, but the sintered body may fracture
Solution Approach 1:
The patent performs preliminary oxygen reduction during the sintering process itself rather than through subsequent nitriding treatment. By controlling the sintering atmosphere and parameters to minimize oxygen incorporation from the start, the patent achieves low oxygen content without the need for aggressive post-processing that could cause fracturing.
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 method enables the production of large, high-strength gallium nitride sintered bodies suitable for sputtering targets, reducing oxygen impurities and enhancing film quality, enabling larger substrate sizes and stable film formation.
Implementation Method 1
a large-sized gallium nitride-based sintered body having a small oxygen amount and high strength... can be prepared by treating a gallium nitride powder having a low oxygen content for an appropriate holding time using a hot press mold
Implementation Method 2
The sputtering method is a method in which a target placed in the cathode is physically bombarded with positive ions such as Ar ions, and by the collision energy, a material constating the target is discharged to deposit a film having a composition substantially the same as the target material on a substrate placed to face the target
Data Source
AI summary
The object of the present invention is to provide a large-sized gallium nitride-based sintered body having a small oxygen amount and high strength, a large-sized gallium nitride-based sintered body having a small oxygen amount and containing a dopant, to obtain a highly crystalline gallium nitride thin film which has become a n-type or p-type semiconductor by a dopant, and methods for producing them.A gallium nitride-based sintered body, which has an oxygen content of at most 1 atm % and an average particle size (D50) of at least 1 μm and at most 150 μm.