GaN Semiconductor Substrate Layout for Low-Dislocation Wide-Area Growth
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Solution Overview
Problem
The production of GaN-based semiconductor layers often results in defects such as threading dislocations, particularly when grown on heterogeneous substrates, which limits the formation of wide, high-quality layers necessary for micro-LEDs and other devices.
Innovation Solution
A semiconductor substrate with a base substrate, a mask layer having an opening and mask portion, and a GaN-based semiconductor layer is formed, where the layer includes a first portion on the mask portion with non-threading dislocations and a second portion on the opening portion with a lower dislocation density, achieved through controlled epitaxial lateral overgrowth and optimized film formation conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a GaN-based thin film is formed on a substrate by semiconductor thin film growth, then the semiconductor device can be produced, but the film contains many threading dislocations that limit the formation of wide, high-quality layers
Solution Approach 1:
The mask layer is divided into discrete opening portions and mask portions, creating a segmented structure that enables selective growth. This segmentation allows the semiconductor layer to grow laterally from the opening portions while being constrained by the mask portions, thereby reducing dislocation propagation and enabling wide-area low-dislocation regions.
Solution Approach 2:
The mask layer serves as an intermediary structure between the substrate and the semiconductor layer. By introducing this intermediate layer with specific opening and mask portions, the patent mediates the growth process to achieve lateral overgrowth while controlling dislocation density, ultimately producing wide-area semiconductor layers with reduced defects.
2Manufacturing precision
If selective growth technique such as ELO method is used to reduce threading dislocations, then dislocation density is reduced, but the process complexity increases
Solution Approach 1:
The mask layer with predetermined opening portions and mask portions is formed before the semiconductor layer growth. This preliminary structuring establishes the growth pattern in advance, allowing the subsequent epitaxial growth to proceed in a controlled manner that naturally reduces dislocations without requiring complex real-time process adjustments.
Solution Approach 2:
The patent utilizes changes in growth parameters during the epitaxial process to achieve lateral overgrowth. By controlling growth conditions such as temperature, pressure, and gas flow, the process transitions from vertical to lateral growth, reducing dislocation density while maintaining process feasibility through parameter optimization rather than structural complexity.
3Area of stationary object
If wide GaN-based semiconductor layers are formed, then larger active regions are achieved, but dislocation density increases
Solution Approach 1:
The mask layer creates local variations in the growth environment through its opening portions and mask portions. This local quality differentiation enables different growth characteristics in different regions: the opening portions promote lateral overgrowth with reduced dislocations, while the mask portions constrain growth and prevent dislocation propagation, collectively achieving wide-area low-dislocation semiconductor layers.
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 allows for the formation of GaN-based semiconductor layers with reduced dislocation density, enabling the production of high-quality semiconductor devices with larger active regions, improving crystallinity and reliability.
Implementation Method 1
a selective growth technique such as an epitaxial lateral overgrowth (ELO) method is known
Data Source
AI summary
A semiconductor substrate includes a base substrate, a mask layer including an opening portion and a mask portion, and a GaN-based semiconductor layer that includes a GaN-based semiconductor. The GaN-based semiconductor layer includes: a first portion located on the mask portion; and a second portion that is located on the opening portion and has a lower dislocation density of non-threading dislocations in a cross section of the GaN-based semiconductor layer taken along a thickness direction than the first portion.