SiC Superjunction Structure With Fewer Epitaxy and Implantation Stages
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Solution Overview
Problem
The conventional methods for manufacturing superjunction silicon carbide semiconductor devices require multiple combinations of epitaxial growth and ion implantation to form a parallel pn structure, leading to long manufacturing lead times and increased costs due to the need for high acceleration energies and thick ion implantation masks, which can cause substrate warping and difficulties in forming favorable trench shapes.
Innovation Solution
A method involving the periodic ion implantation of nitrogen ions at a constant depth in an epitaxially grown p-type drift layer, reducing the number of epitaxial growth and ion implantation stages, and using a range of acceleration energies from 10 keV to 50 MeV to achieve deeper ion penetration, thereby forming a deeper parallel pn structure in fewer steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple combinations of epitaxial growth and ion implantation are used to form parallel pn structure, then the depth and quality of the parallel pn structure is improved, but the manufacturing lead time and process complexity increase
Solution Approach 1:
The patent changes the acceleration energy parameter of ion implantation to a specific range (10 keV to 50 MeV) to achieve deeper ion penetration in fewer stages, and adjusts the implantation depth and concentration parameters to form the required parallel pn structure with adequate depth and quality in reduced process cycles
Solution Approach 2:
The patent employs periodic ion implantation at constant depth intervals to build up the parallel pn structure progressively, allowing controlled formation of deep structures through repeated cycles rather than requiring excessive single-stage implantation or numerous epitaxial growth steps
2Length of stationary object
If high acceleration energy and thick ion implantation masks are used, then deeper ion penetration is achieved, but substrate warping and manufacturing difficulty increase
Solution Approach 1:
The patent optimizes the acceleration energy within a specific range (10 keV to 50 MeV) to achieve sufficient ion penetration depth without requiring excessively high energies that would necessitate thick masks and cause substrate warping, balancing penetration depth with manufacturing ease
Solution Approach 2:
The patent performs ion implantation at controlled depths and concentrations in preliminary stages to gradually form the parallel pn structure, preventing substrate warping by avoiding single-stage deep implantation that would require thick masks and cause manufacturing difficulties
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 reduces the number of stages in the manufacturing process, shortening lead times and lowering costs by enabling deeper ion implantation with fewer process repetitions, while maintaining the necessary depth and quality of the parallel pn structure for high-voltage semiconductor devices.
Implementation Method 1
selectively forming semiconductor regions of the first conductivity type by implanting nitrogen ions in the epitaxial layer
Implementation Method 2
forming an epitaxial layer of the second conductivity type on the front surface of the silicon carbide semiconductor substrate
Data Source
AI summary
A method of manufacturing a superjunction silicon carbide semiconductor device is provided, enabling a reduction of the number of times a combination of epitaxial growth and ion implantation for forming a parallel pn structure is performed. In the method of manufacturing the superjunction silicon carbide semiconductor device, forming an epitaxial layer 2a, 2b of a second conductivity type on a front surface of a silicon carbide semiconductor substrate 1 of a first conductivity type and selectively forming semiconductor regions 4a, 4b of the first conductivity type by implanting nitrogen ions in the epitaxial layer are repeated multiple times, thereby forming the parallel pn structure.