SiC Diode Mesa Termination for Breakdown Voltage
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Solution Overview
Problem
Conventional SiC-PiN diodes experience reduced breakdown voltage when the impurity concentration of the JTE region is shifted, leading to process yield issues due to difficulties in controlling the etching process for the mesa structure unit.
Innovation Solution
A high breakdown voltage semiconductor rectifier is designed with a second conductive buffer layer and a mesa termination unit, which relaxes the electric field and maintains a high breakdown voltage even when the impurity concentration of the JTE region is reduced, eliminating the need for a two-step mesa structure and improving process yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the impurity concentration of the JTE region is reduced to increase breakdown voltage, then the breakdown voltage increases, but the etching process control becomes difficult and process yield decreases
Solution Approach 1:
The patent divides the termination structure into two separate functional units: a mesa termination unit for mechanical support and field distribution, and an electric field relaxation region for voltage control. This segmentation allows the JTE region to be optimized for breakdown voltage without compromising etching process control, as the mesa structure provides geometric constraints that guide the etching process while the relaxed region handles the electrical optimization.
2Manufacturing precision
If a two-step mesa structure is used to control etching precision, then the manufacturing precision improves, but the device complexity increases
Solution Approach 1:
The patent extracts the electric field relaxation function from the mesa structure itself and places it in a separate doped region. This allows the mesa structure to be simplified to a single-step formation that provides only mechanical support and basic field distribution, while the extracted relaxation function is implemented through controlled doping in a separate region, reducing overall device complexity.
3Manufacturing precision
If the impurity concentration of the JTE region is increased to improve etching control, then the etching process control improves, but the breakdown voltage decreases
Solution Approach 1:
The patent applies different impurity concentrations to different regions: the mesa termination unit maintains higher impurity concentration for etching process control and mechanical stability, while the electric field relaxation region uses lower impurity concentration to achieve high breakdown voltage. This local differentiation allows each region to be optimized for its specific function without compromising the other.
Data Source
AI summary
A high breakdown voltage diode of the present embodiment includes a first conductive semiconductor substrate, a drift layer formed on the first conductive semiconductor substrate and formed of a first conductive semiconductor, a buffer layer formed on the drift layer and formed of a second conductive semiconductor, a second conductive high concentration semiconductor region formed at an upper portion of the buffer layer, a mesa termination unit formed on an end region of a semiconductor apparatus to relax an electric field of the end region when reverse bias is applied between the semiconductor substrate and the buffer layer, and an electric field relaxation region formed at the mesa termination unit and formed of a second conductive semiconductor.A breakdown voltage of a high breakdown voltage diode, in which a pn junction is provided to a semiconductor layer, is increased, and a process yield is improved.