SiC Grid Manufacturing With Epitaxy for Rounded Buried Junctions
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Solution Overview
Problem
Current methods for manufacturing buried grids in SiC semiconductors face limitations such as high energy implantation costs, implant damage leading to low emitter efficiency, and complex trench etching processes, which result in electric field crowding and limited surge current capability.
Innovation Solution
A method combining ion implantation and epitaxial growth to create a grid structure with rounded corners, allowing for high doping levels and efficient Ohmic contacts, while simplifying the fabrication process by avoiding costly high-energy implantation and planarization steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is used to create buried grid, then selectively doped areas can be made with controllable homogeneity, but there is a limitation in doping level due to increasing implantation damage with increasing implant dose
Solution Approach 1:
The patent applies preliminary action by performing ion implantation at elevated temperatures before final device operation. This pre-heating treatment allows dopant atoms to diffuse and anneal implantation damage beforehand, reducing defect centers that would otherwise harm emitter efficiency while maintaining the doping homogeneity achieved through precise implantation control
2Length of stationary object
If high energy implantation is used to achieve thicker BG, then greater thickness can be obtained, but it is a high cost process
Solution Approach 1:
The patent changes the temperature parameter during and after ion implantation by performing implantation at elevated temperatures and followed by thermal annealing. This parameter change allows lower energy implantation to achieve the same effective doping depth and thickness as high energy implantation would provide, significantly reducing manufacturing cost while maintaining grid thickness
3Reliability
If etched grid with sharp corners is used, then deep doped structures are possible with damage free doping, but sharp corners result in electric field crowding thus limiting voltage blocking capability
Solution Approach 1:
The patent applies spheroidality by using ion implantation to create naturally rounded doping profiles rather than sharp rectangular corners. The ion implantation process inherently produces Gaussian-like doping distributions with smooth transitions, eliminating electric field crowding at corners while maintaining deep doping capability and high doping quality through controlled implantation parameters
4Strength
If trench filled grid with rounded corners is used, then deep doped structures are possible without electric field crowding, but it is a complicated process involving trench etching, two times regrowth with epitaxy, and planarization with sub-micron accuracy
Solution Approach 1:
The patent extracts and eliminates the complex trench etching, multiple epitaxial regrowth, and precision planarization steps from the manufacturing process. By using direct ion implantation on the surface, the method achieves rounded corner doping profiles and deep doping capability without requiring any trench formation or multiple growth cycles, dramatically simplifying the device fabrication process
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 approach enables efficient electric field shielding, faster switching, and improved surge current handling with reduced resistance and operating temperature, while simplifying the manufacturing process and avoiding expensive high-energy implantation and planarization steps.
Implementation Method 1
by ion implantation at least once at a stage selected from the group consisting of directly after step a), and directly after step b), implanting ions in the first layer n1 to form first regions p1
Implementation Method 2
by epitaxial growth adding at least one doped semiconductor SiC material to form separated second regions p2 on the first layer n1
Data Source
AI summary
A grid is manufactured with a combination of ion implant and epitaxy growth. The grid structure is made in a SiC semiconductor material with the steps of a) providing a substrate comprising a doped semiconductor SiC material, said substrate comprising a first layer (n1), b) by epitaxial growth adding at least one doped semiconductor SiC material to form separated second regions (p2) on the first layer (n1), if necessary with aid of removing parts of the added semiconductor material to form separated second regions (p2) on the first layer (n1), and c) by ion implantation at least once at a stage selected from the group consisting of directly after step a), and directly after step b); implanting ions in the first layer (n1) to form first regions (p1). It is possible to manufacture a grid with rounded corners as well as an upper part with a high doping level. It is possible to manufacture a component with efficient voltage blocking, high current conduction, low total resistance, high surge current capability, and fast switching.