GaN Semiconductor Substrate Structure for Low-Defect Lateral Overgrowth
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Solution Overview
Problem
The existing techniques for forming GaN-based semiconductor layers on substrates with different lattice constants face challenges such as high internal stress, defects, and adhesion issues, which affect the quality and reliability of semiconductor devices.
Innovation Solution
A semiconductor substrate configuration using a main substrate with a lattice constant different from GaN, a mask layer with an opening portion, and a seed portion, where the GaN-based semiconductor layer is grown using the epitaxial lateral overgrowth method, reducing interaction with the mask layer to minimize defects and stress, and optimizing the mask layer's material and thickness to enhance film formation and peeling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If GaN-based semiconductor layer is formed on substrate with different lattice constant, then manufacturing cost is reduced and substrate availability is improved, but internal stress and defects increase
Solution Approach 1:
The patent segments the semiconductor layer formation process into two distinct stages: initial growth on the heterogeneous substrate, and subsequent lateral overgrowth on a mask layer. This segmentation allows the layer to adapt to substrate mismatch initially, then transition to a lower-stress growth mode later, resolving the contradiction between substrate availability and internal stress reduction
Solution Approach 2:
The mask layer serves as an intermediary between the heterogeneous substrate and the final semiconductor structure. It mediates the lattice mismatch by providing a transition zone for lateral overgrowth, enabling the use of cost-effective substrates while maintaining low internal stress in the functional semiconductor regions
2Ease of manufacture
If GaN-based semiconductor layer is formed on substrate with different lattice constant, then manufacturing cost is reduced, but surface defects increase
Solution Approach 1:
The patent divides the semiconductor layer into an initial growth region on the substrate and a lateral overgrowth region on the mask layer. The lateral overgrowth segment is specifically designed to be defect-free by forming on the mask layer rather than directly on the heterogeneous substrate, thus achieving high manufacturing precision while using cost-effective substrates
Solution Approach 2:
The patent extracts the defect formation zone by isolating it to the initial growth region on the heterogeneous substrate. The lateral overgrowth region is deliberately separated from the substrate surface, taking out the defect generation mechanism from the functional semiconductor regions and confining it to a non-critical area
3Strength
If mask layer interaction with semiconductor layer is increased, then adhesion is improved, but defects and stress increase
Solution Approach 1:
The patent applies local quality by creating different interaction characteristics in different regions: strong adhesion between mask layer and semiconductor layer in the lateral overgrowth region for structural integrity, while minimizing interaction in regions where defect propagation could occur. This localized differentiation resolves the contradiction between adhesion strength and defect reduction
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 configuration reduces surface defects, internal stress, and adhesion issues, leading to improved crystallinity and reliability of the GaN-based semiconductor layer, enhancing the performance and yield of semiconductor devices.
Implementation Method 1
a technique for forming a GaN-based semiconductor layer on a GaN-based substrate or a heterogeneous substrate (for example, a sapphire substrate) by using an epitaxial lateral overgrowth (ELO) method
Data Source
AI summary
A semiconductor substrate includes a heterogeneous substrate, a mask layer having an opening portion and a mask portion, a seed portion overlapping the opening portion, and a semiconductor layer including a GaN-based semiconductor and disposed on the seed portion and the mask portion. An upper surface of an effective portion of the semiconductor layer includes at least one low-level defective region with a size of 10 μm in a first direction along a width direction of the opening portion and 10 μm in a second direction orthogonal to the first direction, and a line defect is not measured by a CL method in the low-level defective region.