SiC Current Spreading Layer via Channeled Ion Implantation
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Solution Overview
Problem
The manufacturing process of power electronic devices with current spreading layers on silicon carbide substrates is complex and costly due to the need for multiple epitaxial growths and high-energy ion implantations, which are difficult to control and result in non-uniform doping profiles and depth variations.
Innovation Solution
A channeled ion implantation process is used to form a current spreading layer with precise control over doping and depth, reducing the number of manufacturing steps and improving uniformity by orienting the ion beam along the crystallographic axes of the silicon carbide substrate, allowing for a seamless and continuous doping profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple epitaxial growths are performed to achieve desired thickness and doping, then the current spreading layer can be formed with sufficient thickness, but the manufacturing time and cost increase significantly
Solution Approach 1:
The patent changes the fundamental parameter of doping formation from epitaxial growth to ion implantation. This allows achieving the desired doping profile and thickness in a single step rather than requiring multiple epitaxial growth cycles, thereby reducing manufacturing time while maintaining doping uniformity through precise ion implantation control
Solution Approach 2:
The patent extracts the doping formation step from the epitaxial growth process and performs it separately through ion implantation. This separation allows independent optimization of thickness and doping parameters, achieving the desired current spreading layer characteristics without the time-consuming multi-step epitaxial process
2Productivity
If traditional ion implantation is used to form the current spreading layer, then epitaxial growth steps can be reduced, but the process complexity increases due to multiple implant steps required for uniform doping
Solution Approach 1:
The patent changes the ion implantation parameters by performing implantation in channeling conditions along specific crystallographic axes. This single implantation step with optimized parameters (energy, angle, dose) achieves uniform doping profile without requiring multiple implantation steps, thereby reducing process complexity while maintaining productivity
Solution Approach 2:
The patent performs preliminary preparation by orienting the silicon carbide substrate along specific crystallographic axes <100> or <111> before ion implantation. This preliminary orientation enables the subsequent single-step channeling implantation to achieve uniform doping, avoiding the need for multiple complex implantation steps
3Ease of manufacture
If high energy ion implantation is used to form the current spreading layer, then the doping can be achieved without epitaxial growth, but the doping profile uniformity and depth control become difficult
Solution Approach 1:
The patent optimizes the ion implantation parameters including energy (10-500 keV), angle (channeling angle along crystallographic axes), and dose to achieve precise depth control and uniform doping profile. By carefully selecting these parameters, the process achieves both ease of manufacture and high manufacturing precision in a single step
Solution Approach 2:
The patent utilizes the specific crystallographic structure of silicon carbide material and its anisotropic properties to achieve precise ion implantation. The channeling effect along specific crystal axes <100> or <111> provides natural depth control and uniformity, combining material properties with implantation parameters for optimal results
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 significantly reduces the on-state resistance, breakdown voltage, and drain-source leakage current, while providing precise control over the doping and depth of the current spreading layer, leading to improved performance and reduced manufacturing costs.
Implementation Method 1
forming the current spreading layer (6) includes performing a channeled ion implantation, in a channeling condition, for implanting doping ions having the first electrical conductivity (n) within the semiconductor body (4)
Implementation Method 2
performing a channeled ion implantation, in a channeling condition, for implanting doping ions
Data Source
AI summary
A process for manufacturing a power electronic device, envisages: forming a semiconductor body of silicon carbide, having a first electrical conductivity and a first doping value, and defining a front surface; forming a Current Spreading Layer, CSL, in a surface portion of said semiconductor body facing the front surface, having the first electrical conductivity and a second doping value, greater than the first doping value; forming elementary cells of the power electronic device in an active area of the semiconductor body at the front surface. The step of forming the current spreading layer envisages performing a channeled ion implantation, in a channeling condition, for implanting doping ions having the first electrical conductivity within the semiconductor body.