GaN Template Substrate Void Structure for Low-Defect Overgrowth
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Solution Overview
Problem
Existing techniques for forming GaN layers on heterogeneous substrates, such as silicon or sapphire, result in high defect densities due to threading dislocations, affecting device characteristics and reliability, and the lateral growth method is slow, limiting the formation of wide nitride semiconductor parts.
Innovation Solution
A semiconductor substrate design featuring a template substrate with aligned seed and growth restricting regions, where the seed region is positioned above the growth restricting region, and a first wing with a void space aspect ratio of 5.0 or higher, allowing for rapid formation of a wide nitride semiconductor part with low defect density and improved flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a GaN layer is formed on a heterogeneous substrate using conventional methods, then the defect density becomes high (10^8-10^9 cm^-2), but forming a wide nitride semiconductor part requires slow lateral growth which limits productivity
Solution Approach 1:
The invention transitions from conventional planar lateral growth to three-dimensional overgrowth by forming a semiconductor part that extends vertically above the mask pattern. This dimensional change allows the semiconductor part to grow laterally through vertical extension rather than horizontal spreading, achieving both wide coverage and high growth speed while maintaining low defect density through the ELO mechanism
Solution Approach 2:
The invention segments the growth process into distinct regions: a seed region for nucleation, a mask pattern for defect blocking, and an overgrowth region for wide-area formation. The mask pattern is divided into multiple regions (first mask region, second mask region) that work together to guide selective growth, enabling parallel formation of multiple semiconductor parts simultaneously
2Manufacturing precision
If the laterally grown GaN layer comes into contact with the mask part, then the defect density reduces, but the flatness of the GaN layer deteriorates
Solution Approach 1:
The invention resolves the flatness issue by changing from two-dimensional lateral contact to three-dimensional spatial separation. The semiconductor part grows vertically to a height that positions its upper surface above the mask pattern, eliminating direct contact while maintaining the defect-blocking function. This vertical positioning preserves both low defect density and excellent flatness on the upper surface
Solution Approach 2:
The mask pattern is preliminarily formed with specific dimensions and positioning before the overgrowth process begins. The mask pattern's height and lateral dimensions are pre-configured to ensure that when the semiconductor part grows to its target height, its upper surface will be positioned above the mask, preventing contact while maintaining the defect filtering function during the growth process
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
Enables the formation of a wide nitride semiconductor part with high crystallinity and reduced defect density, suppressing material wrapping around to the back surface and enhancing device quality.
Implementation Method 1
an Epitaxial Lateral Overgrowth (ELO) method has been studied as a technique for forming a GaN layer having a low defect density on the heterogeneous substrate
Data Source
AI summary
A template substrate including a first seed region and a growth restricting region that are aligned in a first direction, and a first semiconductor part positioned above the template substrate are provided, the first semiconductor part includes a first base positioned above the first seed region, and a first wing connected to the first base, the first wing facing the growth restricting region with a first void space interposed therebetween, the first wing includes an edge positioned above the growth restricting region, and a ratio of a width of the first void space with respect to a thickness of the first void space in the first direction is equal to or larger than 5.0.