GaN Epitaxial Mask Window Structure for Dislocation Reduction
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Solution Overview
Problem
The existing methods for growing GaN-based materials using MOCVD technology result in high dislocation densities, which hinder the development of high-voltage GaN-based power devices and long-wavelength LEDs, as they require lower dislocation densities to enhance performance.
Innovation Solution
A semiconductor structure and manufacturing method involving a base with first-type and second-type mask layers, where the first-type mask layer has a larger window area than the second-type mask layer, allowing for epitaxial growth that bends and stops dislocations, reducing dislocation density through lateral epitaxial growth and mask layer interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If general MOCVD epitaxial equipment is used to grow GaN-based materials on conventional bases, then the manufacturing process is simple and easy to operate, but the dislocation density is high (1-3E8/cm3)
Solution Approach 1:
The mask layer is divided into multiple segments including a first mask layer, a second mask layer, and a third mask layer, each with different window sizes and positions. This segmentation allows different regions to serve different functions: the first mask layer with larger windows allows dislocation bending, the second mask layer with smaller windows provides dislocation stopping, and the third mask layer offers additional filtering, collectively reducing dislocation density while maintaining manageable manufacturing complexity
Solution Approach 2:
Different mask layers are designed with locally optimized properties: the first mask layer has larger window areas to enable lateral epitaxial growth and dislocation bending, the second mask layer has smaller window areas to stop dislocations, and each layer uses specific materials with appropriate etching selectivity. This local quality optimization allows each region to address specific dislocation control requirements, achieving high manufacturing precision through targeted local structures
2Manufacturing precision
If the mask layer window areas are optimized to reduce dislocation density, then the epitaxial layer quality improves, but the manufacturing process complexity increases
Solution Approach 1:
The mask layers with specific window patterns are formed before the epitaxial growth process. The first mask layer is prepared with larger windows to enable initial lateral growth and dislocation bending, followed by the second mask layer with smaller windows positioned to stop dislocations. This preliminary arrangement of mask structures with optimized window areas ensures that dislocation control mechanisms are in place before growth begins, achieving high epitaxial layer quality while streamlining the manufacturing process by pre-configuring the dislocation control architecture
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 effectively reduces dislocation density in GaN-based epitaxial layers by bending and stopping dislocations during growth, thereby improving the quality and performance of GaN-based power devices and LEDs.
Implementation Method 1
allowing for epitaxial growth that bends and stops dislocations, reducing dislocation density through lateral epitaxial growth and mask layer interactions
Data Source
AI summary
The present disclosure provides a semiconductor structure, including: a substrate, a first-type mask layer, a second-type mask layer, and an epitaxial layer; where the first-type mask layer includes a first mask multilayer, the first mask multilayer includes a first mask layer and a second mask layer, the first mask layer includes a first window, the second mask layer includes a second window communicating with the first window, the second window and the first window constitute a first-type window, and a cross-section of the second window is larger than that of the first window; the second-type mask layer is located on a side of the first-type mask layer away from the base; the second-type mask layer includes a second-type window communicating with the first-type window, and a cross-section of the second-type window is smaller than that of the second window.