SiC Drift Layer Design for Cosmic Ray Hardness
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Solution Overview
Problem
Semiconductor power devices, such as SiC devices, are vulnerable to destructive single event burnout caused by terrestrial cosmic rays, leading to equipment malfunction and damage, and specific TCR failure rate ratings are often required for certain applications, necessitating the development of methods to design and fabricate devices with specific TCR ratings.
Innovation Solution
A method for manufacturing silicon-carbide (SiC) devices involves selecting a specific TCR rating, determining the breakdown voltage, and designing the drift layer parameters, including doping concentration and thickness, to achieve the desired TCR rating at a specific applied voltage, using relationships like TCR failure rate (FIT/cm²) = 10^(A + B*VBV), where A and B are constant values, V is the applied voltage, and BV is the breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the drift layer doping concentration is increased to reduce breakdown voltage, then the device can operate at lower voltages, but the TCR failure rate increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the drift layer doping concentration and thickness to achieve different breakdown voltage ratings while controlling TCR failure rates. The method establishes mathematical relationships between doping concentration, thickness, breakdown voltage, and TCR failure rate, allowing designers to select optimal parameters for specific application requirements.
Solution Approach 2:
The patent implements local quality by optimizing the drift layer properties (doping concentration and thickness) specifically in the region most susceptible to cosmic ray effects. By tailoring the drift layer characteristics rather than uniformly changing the entire device structure, the method achieves improved TCR performance while maintaining necessary breakdown voltage characteristics.
2Strength
If the drift layer thickness is increased to reduce doping concentration, then the breakdown voltage increases, but the device becomes more susceptible to TCR effects
Solution Approach 1:
The patent uses parameter changes to establish the relationship between drift layer thickness, doping concentration, and TCR failure rate. By varying these parameters systematically, the method identifies optimal combinations that balance breakdown voltage requirements with cosmic radiation hardness, providing a design framework for specific TCR ratings.
Solution Approach 2:
The method applies local quality by specifically engineering the drift layer thickness and doping profile in the critical region where cosmic rays interact with the device. This localized optimization allows the device to achieve the necessary breakdown voltage while minimizing the drift layer volume exposed to cosmic radiation, thereby reducing TCR failure rates.
3Reliability
If custom drift layer parameters are designed for specific TCR ratings, then the device reliability in cosmic radiation environments improves, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies parameter changes by establishing design equations that directly relate drift layer doping concentration and thickness to desired TCR ratings and breakdown voltages. These equations enable manufacturers to calculate precise fabrication parameters from target specifications, simplifying the translation of design requirements into manufacturing parameters and reducing process complexity.
Solution Approach 2:
The method implements preliminary action by providing a complete design framework before fabrication begins. The design equations allow all critical drift layer parameters to be determined in advance based on target TCR ratings and breakdown voltage requirements, enabling manufacturers to prepare precise fabrication specifications ahead of time and execute the manufacturing process with greater ease and consistency.
Data Source
AI summary
In one embodiment, a method of manufacturing a silicon-carbide (SiC) device includes receiving a selection of a specific terrestrial cosmic ray (TCR) rating at a specific applied voltage, determining a breakdown voltage for the SiC device based at least on the specific TCR rating at the specific applied voltage, determining drift layer design parameters based at least on the breakdown voltage. The drift layer design parameters include doping concentration and thickness of the drift layer. The method also includes fabricating the SiC device having a drift layer with the determined drift layer design parameters. The SiC device has the specific TCR rating at the specific applied voltage.