III-Nitride Substrate Non-Uniform Dislocation Density Fracture
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Solution Overview
Problem
Freestanding III-nitride single-crystal substrates with low average dislocation density are prone to fracture, limiting their application in semiconductor devices due to uniform dislocation-density distribution.
Innovation Solution
Creating substrates with a non-uniform dislocation-density distribution, featuring high-dislocation-density regions and low-dislocation-density regions, where the ratio of high-dislocation-density regions to average dislocation density is 2 or greater, to arrest crack propagation and prevent fracturing, while maintaining an average dislocation density of 5 × 10^5 cm^-2 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the average dislocation density is reduced to improve semiconductor device properties, then device performance is improved, but the substrate becomes more prone to fracture
Solution Approach 1:
The substrate is designed with non-uniform dislocation density distribution, creating regions of different dislocation densities (first regions with density of 1×10^5 to 1×10^6 cm^-2 and second regions with density of 5×10^5 to 5×10^6 cm^-2). This local variation in dislocation density allows the substrate to maintain overall low dislocation density for device performance while specific regions provide enhanced fracture resistance.
2Device complexity
If the dislocation density is made uniform to simplify substrate structure, then manufacturing is simplified, but crack propagation cannot be effectively arrested
Solution Approach 1:
The substrate is segmented into multiple regions with different dislocation densities. The first regions and second regions are spatially separated and distributed throughout the substrate, creating a segmented structure that actively arrests crack propagation while maintaining manageable manufacturing complexity through defined geometric patterns.
3Strength
If high-dislocation-density regions are introduced to prevent fracture, then substrate strength is improved, but average dislocation density increases
Solution Approach 1:
The substrate utilizes controlled parameter changes in dislocation density across different regions. By carefully selecting the dislocation density ranges for first regions (1×10^5 to 1×10^6 cm^-2) and second regions (5×10^5 to 5×10^6 cm^-2) and controlling their respective area ratios, the substrate achieves enhanced fracture resistance while maintaining an overall average dislocation density suitable for semiconductor device fabrication.
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 non-uniform dislocation-density distribution effectively prevents substrate fracture and enhances the properties of semiconductor devices by ensuring high yield and superior device performance.
Implementation Method 1
the ratio of the dislocation density of the high-dislocation-density region(s) to the average dislocation density is sufficiently large to check the propagation of cracks in the substrate
Implementation Method 2
growing single-crystal III-nitride onto the III-nitride crystal by vapor-phase deposition
Implementation Method 3
growing III-nitride crystal onto the starting substrate by liquid-phase deposition
Data Source
Figure 1~2
Figure 3A~3D
Figure 4
AI summary
Freestanding III-nitride single-crystal substrates whose average dislocation density is not greater than 5 × 105 cm-2 and that are fracture resistant, and a method of manufacturing semiconductor devices utilizing such freestanding III-nitride single-crystal substrates are made available. The freestanding III-nitride single-crystal substrate includes one or more high-dislocation-density regions (20h), and a plurality of low-dislocation-density regions (20k) in which the dislocation density is lower than that of the high-dislocation-density regions (20h), wherein the average dislocation density is not greater than 5 × 105 cm-2. Herein, the ratio of the dislocation density of the high-dislocation-density region(s) (20h) to the average dislocation density is sufficiently large to check the propagation of cracks in the substrate. And the semiconductor device manufacturing method utilizes the freestanding III-nitride single crystal substrate (20p).