SiC Single Crystal Growth via Offset Angle Adjustment
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Solution Overview
Problem
The existing methods for manufacturing silicon carbide (SiC) single crystals face challenges in reducing defects such as heterogeneous polymorphous crystals, stacking faults, and threading screw dislocations, which hinder the production of high-performance SiC for semiconductor devices.
Innovation Solution
A manufacturing method involving a first growth process and a re-growth process, where the offset angle of the growth surface is systematically adjusted to reduce defects, with each seed crystal having a threading screw dislocation generation region formed on the upstream side, allowing for the controlled reduction of stacking faults and threading screw dislocations through sequential growth steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a c-plane growth method is used to manufacture SiC single crystal, then the growth process is simple and efficient, but the crystal contains great amount of defects including micropipe defects and threading screw dislocations
Solution Approach 1:
The growth process is divided into multiple sequential stages: initial c-plane growth to establish baseline crystal structure, followed by a-plane growth to reduce threading screw dislocations, and final c-plane growth to achieve desired crystal orientation. Each stage targets specific defect reduction while maintaining overall growth efficiency.
Solution Approach 2:
The manufacturing method employs periodic alternation between c-plane and a-plane growth modes. This periodic switching allows the crystal to undergo repeated cycles of defect reduction mechanisms, progressively eliminating threading screw dislocations and micropipe defects while maintaining high growth rates.
2Manufacturing precision
If an a-plane growth method is used to reduce threading screw dislocations, then threading screw dislocations are not generated, but stacking faults are inevitably generated during the growth process
Solution Approach 1:
The method utilizes the stacking faults generated during a-plane growth as a mechanism to eliminate threading screw dislocations. The stacking faults act as pathways for dislocation annihilation, converting the harmful effect of stacking faults into a beneficial reduction of threading screw dislocations that would otherwise compromise device performance.
Solution Approach 2:
The growth parameters including temperature, pressure, and gas flow are dynamically adjusted between c-plane and a-plane growth stages. These parameter changes control the relative formation rates of stacking faults and threading screw dislocations, optimizing the defect reduction process while minimizing harmful defect accumulation.
3Manufacturing precision
If multiple a-plane growth steps are performed to reduce dislocation density exponentially, then threading screw dislocations are reduced, but the process complexity increases and stacking faults are inevitably generated
Solution Approach 1:
Multiple a-plane growth steps are merged into a single continuous process with optimized parameters, eliminating the need for separate growth cycles. This consolidation maintains the exponential dislocation reduction effect while reducing process complexity and minimizing stacking fault generation through sustained optimal growth conditions.
Solution Approach 2:
The growth process maintains continuous useful action by keeping the crystal in an optimal growth state throughout the entire manufacturing cycle. Continuous monitoring and adjustment of growth parameters ensure that dislocation reduction proceeds exponentially without interruption, while minimizing stacking fault formation through sustained controlled conditions.
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 method effectively decreases the density of stacking faults and threading screw dislocations, resulting in high-performance SiC single crystals suitable for semiconductor applications.
Implementation Method 1
a new SiC single crystal is grown by a method such as a sublimation recrystallization method
Data Source
AI summary
A manufacturing method of a SiC single crystal includes a first growth process and a re-growth process. In the first growth process, a first seed crystal made of SiC is used to grow a first SiC single crystal. In the re-growth process, a plurality of growth steps is performed for (n−1) times. In a k-th growth step, a k-th seed crystal is cut out from a grown (k−1)-th SiC single crystal, and the k-th seed crystal is used to grow a k-th SiC single crystal (n≧2 and 2≦k≦n). When an offset angle of a growth surface of the k-th seed crystal is defined as θk, at least in one of the plurality of growth steps, the offset angle θk is smaller than the offset angle θk-1.