Gallium Nitride Substrate via Silicon Nitride Micro-Mask ELO
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for growing high-quality gallium nitride layers on substrates are complex and costly, particularly due to the need for additional processes like forming silicon dioxide masks, which increase process time, cost, and complexity, and are not economically viable for large-scale production.
Innovation Solution
A method involving thermal cleaning of a silicon substrate, in situ formation of a silicon nitride micro-mask with controlled openings, and subsequent epitaxial lateral overgrowth of a gallium nitride layer without the need for a silicon dioxide mask, allowing for in situ processing and reduced process steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicon dioxide mask is used in the typical ELO method to reduce stress from lattice mismatch, then the quality of the gallium nitride layer is improved, but the process complexity and manufacturing cost increase due to additional deposition and photolithography steps
Solution Approach 1:
The invention extracts and eliminates the silicon dioxide mask formation steps (deposition and photolithography) from the ELO process by using a pre-formed silicon nitride micro-mask that is already present on the silicon substrate. This removes the need for additional deposition and photolithography steps while maintaining the stress-reduction function.
Solution Approach 2:
The silicon nitride micro-mask serves multiple functions: it acts as a structural template for ELO growth, provides stress management due to its different thermal expansion coefficient compared to silicon, and eliminates the need for separate mask formation processes. This multi-functionality resolves the contradiction by combining several roles into one component.
2Manufacturing precision
If a silicon dioxide mask is used in the typical ELO method, then stress from lattice mismatch is reduced, but the manufacturing cost increases due to additional process steps
Solution Approach 1:
The invention extracts and eliminates the silicon dioxide mask formation steps (deposition and photolithography) from the ELO process by using a pre-formed silicon nitride micro-mask that is already present on the silicon substrate. This removes the need for additional deposition and photolithography steps while maintaining the stress-reduction function.
Solution Approach 2:
The silicon nitride micro-mask is formed in advance on the silicon substrate before the ELO growth process begins. This preliminary action eliminates the need for subsequent mask formation steps during the ELO process, reducing both manufacturing cost and process complexity.
3Ease of manufacture
If silicon is used as a substrate instead of sapphire or silicon carbide, then the thermal conductivity and cost are improved, but the lattice constant difference causes difficulty in growing gallium nitride
Solution Approach 1:
The invention applies local quality by using a silicon nitride micro-mask with different material properties (thermal expansion coefficient) than the silicon substrate. This localized region provides stress management and lattice matching benefits specifically where needed for ELO growth, while the overall silicon substrate maintains its cost and thermal conductivity advantages.
Solution Approach 2:
The invention uses a composite structure combining silicon substrate with silicon nitride micro-mask. This composite approach leverages the advantages of both materials: silicon provides low cost and good thermal conductivity, while silicon nitride provides stress management and facilitates high-quality gallium nitride layer growth through ELO.
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 simplifies the process, reduces costs, and enhances the quality and thickness of the gallium nitride layer, enabling cost-effective production of high-quality gallium nitride substrates suitable for electronic and optical devices, including large wafers, with improved structural, optical, and electrical properties.
Implementation Method 1
thermal cleaning of a silicon substrate
Implementation Method 2
in situ formation of a silicon nitride micro-mask
Implementation Method 3
in situ formation of a silicon nitride micro-mask
Implementation Method 4
subsequent epitaxial lateral overgrowth of a gallium nitride layer
Implementation Method 5
reduce stress caused by the lattice mismatch and the thermal expansion coefficient difference between the substrate and the gallium nitride layer
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Provided is a method for preparing a substrate for growing gallium nitride and a gallium nitride substrate. The method includes performing thermal cleaning on a surface of a silicon substrate, forming a silicon nitride (Si3N4) micro-mask on the surface of the silicon substrate in an in situ manner, and growing a gallium nitride layer through epitaxial lateral overgrowth (ELO) using an opening in the micro-mask. According to the method, by improving the typical ELO, it is possible to simplify the method for preparing the substrate for growing gallium nitride and the gallium nitride substrate and reduce process cost.