Group III Nitride Substrate Orientation for Blue Shift Suppression
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Solution Overview
Problem
Current methods for manufacturing nitride semiconductor substrates face challenges in achieving smooth surface roughness and reducing polarity-induced blue shifts in light emitting devices, leading to lower emission intensity due to inadequate surface processing techniques.
Innovation Solution
A group III nitride crystal substrate with specific plane orientation and surface roughness characteristics is developed, utilizing X-ray diffraction measurements to ensure uniform distortion, irregular distortion, and plane orientation deviation within predetermined limits, and employing chemical mechanical polishing to enhance surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical polishing is performed on the GaN crystal substrate, then the surface roughness is improved, but a process-induced degradation layer is formed on the substrate surface
Solution Approach 1:
The patent removes the harmful process-induced degradation layer formed by mechanical polishing through subsequent CMP processing or dry etching, separating the surface roughness improvement function from the degradation layer formation
Solution Approach 2:
The patent introduces CMP processing or dry etching as an intermediary step between mechanical polishing and epitaxial growth to eliminate the degradation layer, acting as a mediator that removes harmful effects while preserving surface smoothness
2Manufacturing precision
If CMP processing is performed to remove the degradation layer, then the surface quality is improved, but the processing rate is low causing problems in cost and productivity
Solution Approach 1:
The patent optimizes CMP processing parameters including slurry composition (pH controlling agents, oxidizers), contact pressure, and rotation speed to achieve higher processing rates while maintaining surface quality, transforming the processing conditions to improve productivity
3Object-generated harmful factors
If dry etching is performed to remove the degradation layer, then the degradation layer is removed, but the surface roughness increases
Solution Approach 1:
The patent applies different processing methods to different requirements: dry etching is used when degradation layer removal is the priority, while CMP processing is used when surface smoothness is the priority, allowing localized optimization based on specific needs
Solution Approach 2:
The patent combines multiple processing steps (mechanical polishing + CMP or mechanical polishing + dry etching) to create a composite processing approach that achieves both degradation layer removal and acceptable surface roughness
4Stability of the object's composition
If the substrate surface has high polarity orientation, then the crystal structure is well-defined, but blue shift occurs in light emitting devices reducing emission intensity
Solution Approach 1:
The patent introduces a slight asymmetry by tilting the substrate plane orientation away from the high-symmetry (0001) plane toward (10-10) or (11-20) planes, which reduces polarity-induced piezoelectric effects and suppresses blue shift while maintaining adequate crystal structure
Solution Approach 2:
The patent changes the plane orientation parameter from exactly (0001) to within ±10° of (10-10) or (11-20), transforming the crystal orientation to reduce piezoelectric polarization and eliminate blue shift while preserving emission intensity
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 approach results in a substrate that suppresses blue shifts and increases emission intensity by improving the crystallinity and surface quality of the semiconductor layer, leading to enhanced performance in light emitting devices.
Implementation Method 1
X-ray diffraction measurement performed with variation of X-ray penetration depth from a main surface of the crystal substrate
Implementation Method 2
employing chemical mechanical polishing to enhance surface quality
Implementation Method 3
a plurality of nitride semiconductor layers (e.g., group III nitride semiconductor layers) are epitaxially grown on a substrate
Data Source
AI summary
A group III nitride crystal substrate is provided, wherein, a uniform distortion at a surface layer of the crystal substrate is equal to or lower than 1.7×10−3, and wherein a plane orientation of the main surface has an inclination angle equal to or greater than −10° and equal to or smaller than 10° in a [0001] direction with respect to a plane including a c axis of the crystal substrate. A group III nitride crystal substrate suitable for manufacturing a light emitting device with a blue shift of an emission suppressed, an epilayer-containing group III nitride crystal substrate, a semiconductor device and a method of manufacturing the same can thereby be provided.