Nitride Semiconductor Substrate Epitaxy for Low Dislocation Growth
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Solution Overview
Problem
Conventional methods for growing nitride semiconductor substrates face challenges in achieving low dislocation density and reducing variations in off-angle, which affect surface morphology and light emission uniformity, leading to issues in semiconductor device reliability and performance.
Innovation Solution
A method involving a vapor deposition process where a base substrate with a curved (0001) plane is used, with a first layer grown to expose inclined interfaces that gradually expand, followed by a second layer grown to contract these interfaces, resulting in a substrate with a mirror surface and reduced dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional epitaxial growth method is used on a (0001) plane base substrate, then the manufacturing process is simple, but the crystal quality and dislocation density are insufficient
Solution Approach 1:
The manufacturing process is divided into multiple distinct steps: preparing a base substrate with a curved (0001) plane and controlled off-angle, growing a first layer with inclined interfaces where the (0001) plane disappears, and growing a second layer with a mirror surface. This segmentation allows each step to be optimized independently for crystal quality while managing overall process complexity.
Solution Approach 2:
The base substrate is pre-prepared with a curved (0001) plane and a controlled off-angle distribution before epitaxial growth begins. This preliminary action ensures that the growth conditions are optimized from the start, leading to better crystal quality and lower dislocation density in the final product.
2Reliability
If the (0001) plane is maintained on the surface throughout growth, then the growth process is straightforward, but dislocation density remains high
Solution Approach 1:
Instead of maintaining the (0001) plane on the surface throughout growth, the method inverts the approach by causing the (0001) plane to disappear during the growth of the first layer. The inclined interfaces expand and eliminate the (0001) plane, which fundamentally changes the growth dynamics and reduces dislocation density. This inverted approach is then reversed in the second layer to restore a mirror surface.
Solution Approach 2:
The method changes the surface orientation parameter during growth by transitioning from a (0001) plane to inclined interfaces and back. This parameter change is achieved by controlling the off-angle distribution and allowing the (0001) plane to disappear during first layer growth, then restoring it in the second layer. This dynamic parameter adjustment optimizes dislocation density while managing manufacturing complexity.
3Manufacturing precision
If uniform off-angle distribution is achieved through complex substrate preparation, then crystal quality improves, but manufacturing complexity increases
Solution Approach 1:
The base substrate is prepared with a specific local quality: a curved (0001) plane with a controlled off-angle distribution. This local characteristic is engineered into the substrate before growth, allowing uniform off-angle distribution to be achieved without overly complex preparation processes. The curvature and off-angle control are localized properties that simplify the overall manufacturing complexity while improving crystal quality.
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 improves crystal quality, reduces dislocation density, and stabilizes the off-angle variation, enhancing the surface morphology and light emission uniformity of nitride semiconductor substrates.
Implementation Method 1
a first step of epitaxially growing a single crystal of a group III nitride semiconductor having a top surface with (0001) plane exposed, directly on the main surface of the base substrate
Implementation Method 2
a method for manufacturing a nitride semiconductor substrate using a vapor deposition method
Data Source
AI summary
A method of making a semiconductor including a step of preparing a base substrate; a first step of epitaxially growing a single crystal of a group III nitride semiconductor having a top surface with (0001) plane exposed, directly on the main surface of the base substrate, forming a plurality of concaves composed of inclined interfaces other than the (0001) plane on the top surface, gradually expanding the inclined interfaces toward an upper side of the main surface of the base substrate, making the (0001) plane disappear from the top surface, and growing a first layer whose surface is composed only of the inclined interfaces; and a second step of epitaxially growing a single crystal of a group III nitride semiconductor on the first layer, making the inclined interfaces disappear, and growing a second layer having a mirror surface, and a semiconductor made thereby.