III-Nitride Semiconductor Buffer Layer Sputtering
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Solution Overview
Problem
The challenge lies in stably obtaining a III group nitride compound semiconductor layer with good crystallinity using existing deposition methods, particularly due to large lattice mismatches between substrates and III group nitride compound semiconductor crystals, which hinders epitaxial growth and results in poor crystal quality.
Innovation Solution
A deposition method combining sputtering and metal-organic chemical vapor deposition (MOCVD) techniques, where a buffer layer is formed at a lower temperature using sputtering, and a thicker underlying layer with good uniformity is achieved, followed by forming light-emissive and contact layers using MOCVD, enhancing crystallinity and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a III group nitride compound semiconductor crystal is epitaxially grown directly on a sapphire substrate or SiC substrate by MOCVD method, then the production process is simplified, but the crystal quality deteriorates due to large lattice mismatch (16% for sapphire-GaN, 6% for SiC-GaN)
Solution Approach 1:
A buffer layer is formed on the substrate before epitaxial growth of the III group nitride compound semiconductor crystal. This preliminary action addresses the lattice mismatch issue by providing an intermediate layer that facilitates better crystal growth, thereby improving crystal quality without significantly complicating the overall production process.
2Manufacturing precision
If a buffer layer is formed by RF sputtering followed by MOCVD growth, then crystal quality is improved, but the production time increases due to multiple deposition steps
Solution Approach 1:
The formation of the buffer layer by RF sputtering and the subsequent MOCVD growth are combined in a sequential process. This merging of deposition methods allows the buffer layer to be formed quickly by sputtering, followed by continuous MOCVD growth, thereby improving crystal quality while minimizing additional production time.
3Reliability
If the buffer layer is annealed in mixed gas of ammonia and hydrogen or formed by DC sputtering at high temperature, then crystal quality is stabilized, but the process complexity and energy consumption increase
Solution Approach 1:
The buffer layer formation process utilizes parameter changes by controlling the RF sputtering conditions (power, pressure, gas flow) to optimize the buffer layer quality. This approach stabilizes crystal quality through controlled parameter optimization rather than requiring additional annealing steps or high-temperature DC sputtering, thereby reducing process complexity.
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 allows for the stable formation of III group nitride compound semiconductor layers with improved crystallinity and uniformity, leading to the production of high-quality light-emitting diodes and other semiconductor devices with enhanced characteristics and efficiency.
Implementation Method 1
a buffer layer and an underlying layer are formed by a sputtering method
Implementation Method 2
a carrier gas is mixed with vapor of a raw material and the mixture is transported onto the surface of a substrate, and then the raw material is decomposed by a reaction with the heated substrate, and thus crystal growth occurs
Data Source
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AI summary
The present invention provides a deposition method of a multilayered structure composed of a III group nitride compound semiconductor having good crystallinity on a substrate. The multilayered structure comprises at least a buffer layer and an underlying layer from the substrate side, and the buffer layer and the underlying layer are formed by a sputtering method. A deposition temperature of the buffer layer is adjusted to a temperature lower than a deposition temperature of the underlying layer, or the thickness of the buffer layer is adjusted to 5 nm to 500 nm. Furthermore, the multilayered structure comprises at least an underlying layer and a light-emissive layer from the substrate side and the underlying layer is formed by a sputtering method, and the method comprises the step of forming the light-emissive layer by a metal-organic chemical vapor deposition (MOCVD method).