Gallium Nitride Sputtering Target for Low-Oxygen GaN Films
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Solution Overview
Problem
Existing methods for forming gallium nitride thin films by sputtering face challenges such as low crystallinity, oxygen contamination, and instability due to high oxygen content and resistivity, leading to inferior film quality and homogeneity, especially when using metal gallium targets or sintered bodies under high pressure.
Innovation Solution
A gallium nitride-based film with improved crystallinity is produced by sputtering a sintered body with low oxygen content and low resistivity, using a method that includes hot pressing of gallium nitride powder with controlled specific surface area and particle size, and forming the film under specific vacuum conditions, which reduces oxygen inclusion and enhances film density and homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal gallium target is used for sputtering, then the sputtering process can be conducted, but the gallium nitride film cannot be obtained with high crystallinity and transparency due to gallium melting at low temperature
Solution Approach 1:
The patent changes the physical state parameter of gallium from solid metal to liquid metal by controlling temperature above its melting point (29.8°C), enabling the formation of high-quality gallium nitride films with improved crystallinity and transparency that cannot be achieved using solid metal gallium targets
Solution Approach 2:
The patent creates a composite system combining liquid metal gallium with nitrogen atmosphere during sputtering, allowing the liquid gallium to react with nitrogen and form gallium nitride film with superior properties compared to conventional solid target methods
2Volume of stationary object
If a gallium nitride sintered body is densified under very high pressure (58 Kbar), then high density is achieved, but the apparatus is 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 (1-10 Kbar), achieving comparable or superior density through a combination of lower pressure sintering followed by controlled heating treatment, thereby avoiding the need for expensive high-pressure apparatus
Solution Approach 2:
The patent performs preliminary sintering to form a green body with moderate density, then applies heating treatment to achieve final densification, avoiding the need for direct high-pressure densification and enabling preparation of large-sized sintered bodies
3Manufacturing precision
If oxygen is reduced from gallium nitride sintered body to improve film quality, then film homogeneity improves, but the sintered body may fracture
Solution Approach 1:
The patent changes the oxygen content parameter to an optimized range (0.1-5.0 at%) rather than minimizing it completely, maintaining sufficient oxygen to prevent sintered body fracture while keeping it low enough to ensure film homogeneity and high quality
4Reliability
If metal gallium is infiltrated into sputtering target to reduce resistivity, then discharge stability improves, but metal gallium deposits during bonding or sputtering and reacts with solder material causing peeling
Solution Approach 1:
The patent applies local quality by creating a gradient structure where metal gallium is present in the sputtering target to ensure discharge stability, but the bonding interface is designed to prevent gallium migration and reaction with solder material, thereby maintaining both discharge stability and bonding integrity
5Reliability
If a tungsten thin film is used to line the gallium nitride formed product to prevent metal gallium deposition, then peeling is prevented, but the number of preparation steps increases and expensive tungsten material is required
Solution Approach 1:
The patent extracts the barrier function from a separate tungsten film layer and integrates it into the sputtering target structure itself through controlled metal gallium infiltration, eliminating the need for additional lining steps and expensive tungsten material while maintaining bonding stability
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 resulting gallium nitride film exhibits high crystallinity, reduced oxygen content, and improved density, enabling its use in semiconductor devices and light-emitting elements with enhanced performance and stability.
Implementation Method 1
A gallium nitride thin film can be formed by a metal organic chemical vapor deposition (MOCVD) method or a sputtering method
Implementation Method 2
a method of hot pressing, which comprises using a gallium nitride powder having a specific surface area of at most 1.5 m2/g and an average particle size of at least 0.5 μm and at most 3 μm
Data Source
AI summary
The object of the present invention is to provide a sputtering target for a gallium nitride thin film, which has a low oxygen content, a high density and a low resistivity. A gallium nitride powder having powder physical properties of a low oxygen content and a high bulk density is used and hot pressing is conducted at high temperature in high vacuum to prepare a gallium nitride sintered body having a low oxygen content, a high density and a low resistivity.