SiC Substrate Ion Implantation Etch Pit Dislocation Reduction
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Solution Overview
Problem
Existing methods for reducing threading screw dislocations in silicon carbide (SiC) crystals, which affect device performance, require forming p-type and n-type layers sequentially and can introduce distortions or generate polymorphous crystals, making them inefficient and time-consuming.
Innovation Solution
A manufacturing method involving ion implantation, annealing, and epitaxial growth on a substrate with chemically etched etch pits to form a SiC growth layer without threading screw dislocations, where the growth conditions ensure that the SiC growth layer joins only on the inner walls of the etch pits, thereby restricting dislocation transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If p-type and n-type layers are formed sequentially to reduce threading dislocations, then dislocation reduction is achieved, but manufacturing time increases and process complexity increases
Solution Approach 1:
The invention extracts and removes the problematic threading dislocations by forming etch pits at their locations through selective chemical etching. The dislocations are physically removed from the crystal structure by creating凹陷 regions, eliminating the need for complex sequential layer formation to suppress their effects.
Solution Approach 2:
The invention applies local quality by creating etch pits only at specific locations where threading dislocations are present. The chemical etching selectively attacks regions with dislocations, creating localized modifications that prevent dislocation propagation without requiring global process changes or multiple layered structures.
2Reliability
If p-type and n-type layers are formed sequentially to reduce threading dislocations, then dislocation reduction is achieved, but device complexity increases
Solution Approach 1:
The invention extracts and removes the problematic threading dislocations by forming etch pits at their locations through selective chemical etching. The dislocations are physically removed from the crystal structure by creating凹陷 regions, eliminating the need for complex sequential layer formation to suppress their effects.
Solution Approach 2:
The invention applies local quality by creating etch pits only at specific locations where threading dislocations are present. The chemical etching selectively attacks regions with dislocations, creating localized modifications that prevent dislocation propagation without requiring global process changes or multiple layered structures.
3Reliability
If etch pits are filled with material other than SiC to reduce threading dislocations, then dislocation propagation is restricted, but polymorphous crystals are generated
Solution Approach 1:
The invention maintains crystal homogeneity by filling etch pits with SiC material that matches the surrounding crystal structure. This ensures that the filled regions are indistinguishable from the original crystal, preventing the formation of polymorphous crystals while still blocking dislocation propagation paths.
Solution Approach 2:
The invention changes the physical state of the etch pit filling process by using epitaxial growth to deposit SiC material that integrates seamlessly with the existing crystal lattice. This parameter control ensures proper crystal orientation and structure, preventing polymorphous crystal formation while maintaining dislocation blocking functionality.
4Reliability
If ion implantation and chemical etching are performed to form etch pits, then threading dislocations are reduced, but additional process steps are required
Solution Approach 1:
The invention merges multiple functions into the chemical etching process. The etching step simultaneously creates etch pits for dislocation removal, defines device regions, and prepares surfaces for subsequent growth, reducing the total number of separate process steps compared to sequential layer formation methods.
Solution Approach 2:
The ion implantation and chemical etching are performed as preliminary actions to prepare the substrate by removing dislocations before the main device fabrication begins. This preliminary preparation simplifies subsequent processing by eliminating the need for complex dislocation management during device formation.
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 reduces threading screw dislocations and prevents the transfer of polymorphous crystals, resulting in high-quality SiC single crystals suitable for semiconductor devices with reduced leakage, such as MOSFETs and diodes, without the need for sequential p-type and n-type layer formation.
Implementation Method 1
implanting ions into a surface portion of the silicon carbide substrate to form an ion implantation layer
Implementation Method 2
activating the ions implanted into the surface portion of the silicon carbide substrate by annealing
Implementation Method 3
chemically etching the surface portion of the silicon carbide substrate to form an etch pit that is caused by a threading screw dislocation included in the silicon carbide substrate
Implementation Method 4
performing an epitaxial growth of silicon carbide to form a silicon carbide growth layer on a surface of the silicon carbide substrate including an inner wall of the etch pit
Data Source
AI summary
A manufacturing method of an SiC single crystal includes preparing an SiC substrate, implanting ions into a surface portion of the SiC substrate to form an ion implantation layer, activating the ions implanted into the surface portion of the SiC substrate by annealing, chemically etching the surface portion of the SiC substrate to form an etch pit that is caused by a threading screw dislocation included in the SiC substrate and performing an epitaxial growth of SiC to form an SiC growth layer on a surface of the SiC substrate including an inner wall of the etch pit in such a manner that portions of the SiC growth layer grown on the inner wall of the etch pit join with each other.