GaN Epitaxial Mask Structure for Lower Dislocation Density
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Solution Overview
Problem
The demand for GaN-based semiconductor devices with reduced dislocation density is increasing to support higher voltage applications and longer wavelength LEDs, as traditional MOCVD epitaxial growth on aluminum trioxide substrates results in dislocation surface densities that are not sufficient for advanced power and display devices.
Innovation Solution
A semiconductor structure and manufacturing method involving a base with a first mask layer having a window that exposes the base, where the window's opening end is away from the base and the bottom wall end is close, with an epitaxial growth process that reduces dislocation density by terminating dislocations within the GaN-based material growth, utilizing a multi-layered mask structure and epitaxial layers to control dislocation extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional MOCVD epitaxial growth on aluminum trioxide substrates is used, then the manufacturing process is simple and成熟, but the dislocation density of GaN-based materials remains high (1E8/cm³ to 3E8/cm³)
Solution Approach 1:
The mask layer is divided into multiple sub-layers (first mask layer, second mask layer, third mask layer) with each layer having specific functions. The first mask layer defines the window opening, the second mask layer terminates dislocations at the bottom wall end, and the third mask layer provides additional dislocation termination. This segmentation allows systematic control of dislocation propagation while maintaining manufacturing feasibility.
Solution Approach 2:
The patent introduces a vertical dimension to dislocation control by creating a three-dimensional mask structure with varying thicknesses at different locations. The mask layers have different thicknesses at the opening end versus the bottom wall end, creating a graded structure that terminates dislocations in the vertical growth direction while allowing controlled epitaxial growth.
2Productivity
If the window opening area is increased to improve epitaxial growth, then the growth area is larger, but dislocation extension is more severe
Solution Approach 1:
The mask layers have different thicknesses at different locations within the window structure. The second mask layer is positioned at the bottom wall end with specific thickness to terminate dislocations, while the third mask layer provides additional local protection. This local quality variation allows the opening end to have large area for growth while the bottom wall end has enhanced dislocation termination capability.
Solution Approach 2:
The second mask layer acts as an intermediary structure between the base and the epitaxial growth region. It is positioned at the bottom wall end of the window and serves as a dislocation termination layer, intercepting dislocations before they can extend into the main growth area, thereby mediating between the need for large growth area and low dislocation density.
3Manufacturing precision
If multiple mask layers are added to terminate dislocations, then dislocation density is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The second mask layer is formed in advance before the main epitaxial growth process, positioned at the bottom wall end of the window structure. This preliminary action creates a dislocation termination structure that will be in place during subsequent growth, preventing dislocation extension without requiring complex real-time control during epitaxial growth.
Solution Approach 2:
The mask structure is organized in a nested hierarchy where the first mask layer defines the outer window boundary, the second mask layer is nested within at the bottom wall end for dislocation termination, and the third mask layer provides additional nested protection. This nested structure allows multiple functional layers to be integrated systematically.
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 method effectively reduces dislocation density in GaN-based materials, facilitating the growth of high-quality semiconductor devices with improved performance for power and display applications by terminating dislocations and increasing the nucleation area, thus enhancing the epitaxial growth process.
Implementation Method 1
an epitaxial growth process that reduces dislocation density by terminating dislocations within the GaN-based material growth
Data Source
AI summary
In the present disclosure, a semiconductor structure and a manufacturing method of the semiconductor structure are provided. The semiconductor structure includes a base, a first mask layer, a first epitaxial layer, and a second epitaxial layer. The first mask layer is located on the base, and the first mask layer has a first window that exposes the base. The first window includes an opening end far from the base and a bottom wall end close to the base. On the plane where the base is located, the orthographic projection of the opening end falls within the bottom wall end.