Beta-Ga2O3 Substrate Hole Distribution for Crack Suppression
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Solution Overview
Problem
Existing beta-Ga2O3 single crystal substrates face challenges with high cracking defect rates and line-shaped hole densities, particularly for larger diameters, which affect the yield and reliability of semiconductor devices.
Innovation Solution
A beta-Ga2O3 single crystal substrate design with a specific distribution of line-shaped holes, where the density in the outer peripheral region is higher than the central region, and a manufacturing method using a platinum-rhodium alloy crucible and controlled thermal processes to reduce cracking defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter of the beta-Ga2O3 single crystal substrate is increased to 100 mm or more, then the productivity and yield are improved, but the cracking defect rate increases and reliability deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of line-shaped holes across the substrate surface. Specifically, the density of line-shaped holes is controlled to be higher in the outer peripheral region (second region) than in the central region (first region). This localized variation in defect distribution creates corresponding variations in thermal stress during cooling, with compressive stresses concentrated in the outer region and tensile stresses in the central region. The compressive stresses in the outer region prevent crack initiation and propagation, thereby reducing the overall cracking defect rate and improving substrate reliability for large-diameter wafers.
2Ease of manufacture
If the density of line-shaped holes is uniformly distributed across the substrate, then the manufacturing process is simple, but the cracking defect rate increases due to uniform thermal stress distribution
Solution Approach 1:
The patent deliberately introduces non-uniform local quality by controlling the density of line-shaped holes to vary across the substrate. The first density (central region) is made lower than the second density (outer peripheral region). This controlled non-uniformity creates a corresponding non-uniform thermal stress distribution during cooling, where compressive stresses are concentrated in the outer region. This stress distribution pattern prevents crack formation and propagation, significantly reducing the cracking defect rate while maintaining manufacturing feasibility through controlled epitaxial growth processes.
3Reliability
If the second density of line-shaped holes is increased to 1000 cm-2 or more in the outer peripheral region, then the cracking defect rate is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by establishing specific quantitative criteria for the density distribution of line-shaped holes. The first density (central region) is controlled to be 500 cm-2 or less, while the second density (outer peripheral region) is controlled to be 1000 cm-2 or more, with the ratio of second density to first density being 2.0 or more. These specific parameter ranges create the desired thermal stress distribution pattern that prevents cracking. The patent provides detailed control parameters and measurement methods to achieve and verify this non-uniform density distribution, making the manufacturing process achievable with standard precision controls.
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 substrate design and manufacturing method significantly reduce cracking defects, enhancing the yield and reliability of semiconductor devices by managing thermal stresses during cooling and epitaxial film growth.
Implementation Method 1
managing thermal stresses during cooling and epitaxial film growth
Data Source
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AI summary
A beta-digallium trioxide single crystal substrate has a circular main surface, and has a diameter of 100 mm or more. The main surface is a (001) plane of a beta-digallium trioxide single crystal; or is a face having an off-angle of more than 0° and 10° or less from the (001) plane of the single crystal, and having an off-direction in a [010] direction of the single crystal or a direction orthogonal to the [010] direction. Second density/first density, which is a ratio between a first density that is a density of line-shaped holes in a first region having a diameter of a length of 0.75D centered at the center of the main surface, and a second density that is a density of line-shaped holes in a second region which is a region outside the first region on the main surface, is larger than 1.0. The second density is 1000 cm-2 or less. D represents a diameter of the substrate, and a unit of the D is mm. The line-shaped hole has a length of 10 µm or more and 200 µm or less, a width of 0.01 µm or more and 2 µm or less, and a depth of 0.1 µm or more.