Composite Silicon Substrate Reinforcement for GaN Cooling Stress
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Solution Overview
Problem
Silicon substrates used for GaN epitaxial growth have low strength and a high probability of fragmentation due to stress during the cooling process after epitaxial growth, leading to defects and reduced quality.
Innovation Solution
A composite substrate is created by integrating poly-crystal or amorphous strengthening structures within a single-crystal silicon substrate, which helps to withstand stress, constrain deformation, and prevent dislocation extension, thereby enhancing mechanical strength and reducing fragmentation risk. This is achieved through a manufacturing method involving the formation of grooves and filling them with strengthening materials like silicon dioxide, silicon nitride, or amorphous silicon, followed by lateral epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silicon substrate is used for GaN epitaxial growth, then thermal conductivity and cost are improved, but mechanical strength is reduced and fragmentation probability increases
Solution Approach 1:
The patent creates a composite substrate structure by integrating poly-crystal or amorphous strengthening structures within the single-crystal silicon substrate. These strengthening structures act as reinforcement elements that increase mechanical strength while preserving the silicon substrate's thermal conductivity properties, thus resolving the contradiction between thermal performance and mechanical strength.
Solution Approach 2:
The strengthening structures are strategically positioned within the silicon substrate at specific locations where stress concentration occurs during cooling. By locally enhancing the substrate structure rather than uniformly modifying the entire substrate, the patent improves mechanical strength where needed while maintaining the overall thermal conductivity of the silicon material.
2Ease of manufacture
If silicon substrate is used for GaN epitaxial growth, then cost and thermal conductivity are improved, but fragmentation probability increases due to stress during cooling
Solution Approach 1:
The strengthening structures are pre-integrated into the silicon substrate before GaN epitaxial growth and subsequent cooling processes. These structures serve as preventive reinforcement that cushions against thermal stress and prevents fragmentation before it occurs during the cooling phase, thereby improving reliability without adding post-processing steps that would increase cost.
3Area of stationary object
If silicon substrate is used for GaN epitaxial growth, then large wafer size and thermal conductivity are improved, but defect density increases due to fragmentation
Solution Approach 1:
The strengthening structures are divided into multiple discrete elements distributed across the silicon substrate surface. This segmentation allows the substrate to better manage thermal stress across large wafer areas, preventing catastrophic fragmentation and reducing defect density while maintaining the advantage of large wafer size for high-volume production.
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 composite substrate exhibits improved mechanical strength and reduced fragmentation, along with lower defect density, enabling the production of high-quality GaN epitaxial layers by effectively managing stress and dislocation issues.
Implementation Method 1
The composite substrate includes: a substrate; and a plurality of strengthening structures disposed within the substrate at intervals... which helps to withstand stress, constrain deformation
Implementation Method 2
prevent dislocation extension, thereby enhancing mechanical strength and reducing fragmentation risk
Implementation Method 3
followed by lateral epitaxial growth
Data Source
AI summary
Disclosed are a composite substrate and a manufacturing method therefor, and a semiconductor device structure. The composite substrate includes a substrate and a plurality of strengthening structures, where the plurality of strengthening structures are disposed within the substrate at intervals, and a material of the plurality of strengthening structures is a poly-crystal material or an amorphous material. The composite substrate provided by the present disclosure may withstand stress, constrain deformation, and prevent extension of a dislocation by providing the strengthening structures inside the substrate, thereby enhancing mechanical strength of the composite substrate. By filling the poly-crystal material or the amorphous material in the single-crystal substrate, the extension of the dislocation in single-crystal substrate may be prevented, so that the strength of substrate may be improved, and probability of fragmentation of the composite substrate may be reduced.