Monocrystalline SiC Substrate Pinning Regions for Dislocation Control
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Solution Overview
Problem
High dislocation densities in monocrystalline silicon carbide (SiC) substrates hinder the yield and reliability of semiconductor devices, as dislocations significantly impact device performance, particularly in regions subjected to voltage.
Innovation Solution
A monocrystalline SiC substrate with intentionally arranged pinning regions on its surface, which act as potential wells to attract and concentrate dislocations away from the device region, reducing dislocation density in the central portion and improving the yield of semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional monocrystalline SiC substrate manufacturing is used, then production cost and manufacturing simplicity are maintained, but dislocation density remains high which reduces device yield
Solution Approach 1:
Pinning regions are formed on the seed crystal surface before SiC monocrystal growth begins. These regions create potential wells that预先 attract and concentrate dislocations during the growth process, preventing them from propagating into the device region and thereby reducing dislocation density in the final substrate.
Solution Approach 2:
The substrate surface is divided into different functional regions: pinning regions with high dislocation attraction capability and device regions with low dislocation density requirements. This local differentiation allows dislocations to be concentrated in specific areas while maintaining high quality in the device fabrication regions.
2Reliability
If pinning regions are added to the substrate structure, then dislocation density in device regions is reduced, but substrate structure complexity increases
Solution Approach 1:
The pinning region pattern is formed on the seed crystal before growth, allowing the complex structure to be established once at the beginning rather than requiring continuous complexity during manufacturing. The subsequent growth process automatically utilizes this pre-established pattern to guide dislocation distribution.
3Manufacturing precision
If pinning regions are formed on the seed crystal, then dislocation distribution is improved in the final substrate, but additional manufacturing steps are required
Solution Approach 1:
The pinning region pattern is formed on the seed crystal surface before the SiC monocrystal growth process begins. This preliminary structuring of the seed crystal allows dislocation control to be built into the growth process itself, rather than requiring additional post-growth treatment steps.
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 method effectively reduces dislocation density in the voltage-applied regions of semiconductor devices, thereby lowering failure probabilities and enhancing the overall yield of semiconductor devices manufactured from these substrates.
Implementation Method 1
Each of the pinning regions is configured to provide a potential well which is capable to attract dislocations from a region surrounding said pinning region
Implementation Method 2
annealing the processed seed crystal at a first preset temperature for a first preset period under protection of an inert gas
Implementation Method 3
growing a SiC monocrystal by using the annealed seed crystal, which is disposed in a furnace, through physical vapor transport
Data Source
AI summary
A monocrystalline SiC substrate comprising a first surface and a second surface. The first surface comprises pinning regions and a device region. Each of the pinning regions is configured to provide a potential well which is capable to attract dislocations from a region surrounding said pinning region. The device region is configured to provide a part of the monocrystalline SiC substrate for manufacturing a semiconductor device. The device region is surrounded by the pinning regions, and a density of dislocations in a central portion of the device region is smaller than a density of dislocations in an edge of the device region due to the pinning regions. The pinning regions surrounding the device region attracts dislocations of the device region into the edge portion, so that the density of dislocations in the central portion is reduced. A yield of the semiconductor devices is improved.