SiC Device Inorganic Passivation Edge Termination
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Solution Overview
Problem
Silicon carbide devices face challenges with high electrical fields at the semiconductor surface, leading to stress on passivation layers, and moisture accumulation in organic passivation materials like polyimide, which can cause corrosion, affecting breakdown behavior and long-term reliability.
Innovation Solution
An inorganic passivation layer structure is used to reduce electric fields and prevent moisture contact, combined with a buried lateral silicon carbide edge termination region to enhance field reduction and protection, allowing for the use of organic materials with better moisture resistance and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyimide passivation is used to protect silicon carbide surface, then breakdown resistance is improved, but moisture accumulation occurs causing corrosion
Solution Approach 1:
An inorganic passivation layer is introduced as an intermediary between the silicon carbide surface and the polyimide passivation layer. This intermediate layer prevents moisture from reaching the silicon carbide surface while allowing the polyimide to provide its breakdown resistance function, thus resolving the contradiction between improved breakdown resistance and long-term reliability.
Solution Approach 2:
The patent employs a composite passivation structure combining inorganic material (such as silicon oxide or silicon nitride) with organic polyimide material. This composite approach leverages the moisture barrier properties of the inorganic layer and the high breakdown resistance of polyimide, simultaneously addressing both reliability and strength requirements.
2Power
If high electric fields occur at silicon carbide surface, then device performance is maintained, but stress on passivation layers increases
Solution Approach 1:
The inorganic passivation layer serves as a mediator that can withstand high electric fields generated by the silicon carbide device operation. This intermediate layer protects the outer polyimide passivation layer from excessive stress while maintaining the high field performance characteristics of the silicon carbide device.
Solution Approach 2:
The patent modifies the passivation structure by changing the material parameters - introducing an inorganic layer with different dielectric properties and mechanical strength characteristics. This parameter change allows the passivation system to handle high electric fields without compromising the integrity of the outer organic passivation layer.
3Ease of manufacture
If organic passivation material is used, then ease of manufacture is improved, but moisture resistance deteriorates
Solution Approach 1:
The patent creates a composite passivation system where an inorganic layer (deposited using standard semiconductor fabrication techniques) is combined with an organic polyimide layer. This composite structure maintains the ease of manufacture advantage through established deposition and curing processes while dramatically improving moisture resistance through the inorganic barrier layer.
Solution Approach 2:
The passivation function is segmented into two distinct layers: an inorganic layer specifically tasked with moisture barrier functionality and an organic polyimide layer focused on providing electrical insulation and mechanical protection. This segmentation allows each layer to optimize its specific function while maintaining manufacturing simplicity.
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
The solution effectively reduces surface electric fields, prevents corrosion, and enhances the breakdown behavior and long-term reliability of silicon carbide devices by using an inorganic passivation layer and buried edge termination region, enabling the use of organic materials with improved moisture resistance.
Implementation Method 1
the silicon carbide substrate and the inorganic passivation layer structure are configured so that an electric field at a surface of the inorganic passivation layer structure located opposite to the silicon carbide substrate is lower than 500 kV/cm while at least one region of the silicon carbide substrate comprises at least an electric field of 2.3 MV/cm
Data Source
AI summary
A silicon carbide device includes a silicon carbide substrate, an inorganic passivation layer structure and a molding material layer. The inorganic passivation layer structure laterally covers at least partly a main surface of the silicon carbide substrate and the molding material layer is arranged adjacent to the inorganic passivation layer structure.