SiC Die Passivation Structure for Edge Oxidation and Delamination
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Solution Overview
Problem
Silicon carbide semiconductor bodies are prone to oxidation at their lateral edges, particularly due to humidity and electrical fields, which can lead to mechanical stress and delamination risks.
Innovation Solution
A passivation system is implemented with an organic layer extending laterally beyond the inorganic passivation layer to cover the critical edges, reducing oxidation and delamination risks, and an additional adhesion promoter or etch stop layer can be included to enhance adhesion and control layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic passivation layer system is formed on the SiC semiconductor body, then protection against oxidation is improved, but delamination risk increases due to mechanical stress at lateral edges
Solution Approach 1:
The patent employs a composite passivation system combining inorganic passivation layers (such as silicon nitride or silicon oxide) with an organic passivation layer (such as polyimide). This composite structure allows the inorganic layer to provide oxidation protection while the organic layer acts as a stress buffer that reduces mechanical stress at the lateral edges, thereby preventing delamination and maintaining adhesion strength.
2Reliability
If the inorganic passivation layer system is extended to cover the lateral edges, then oxidation protection is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the passivation function into two distinct layers with different roles: the inorganic passivation layer system that provides oxidation protection, and the organic passivation layer that provides mechanical stress relief. This segmentation allows each layer to be optimized independently for its specific function, simplifying the overall design and manufacturing process compared to a single complex layer.
3Strength
If the organic layer extends beyond the inorganic passivation layer system, then delamination risk is reduced, but material consumption increases
Solution Approach 1:
The patent applies the organic passivation layer selectively at critical locations where delamination risk is highest, particularly at the lateral edges of the inorganic passivation layer system. The organic layer extends beyond the inorganic layer specifically at these edge regions where stress concentration occurs, while maintaining appropriate coverage elsewhere. This localized application optimizes adhesion strength without excessive material consumption.
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 organic layer effectively delays silicon carbide oxidation and reduces mechanical stress, enhancing the reliability and integrity of the semiconductor die by preventing delamination.
Implementation Method 1
The organic layer covering the lateral edge of the inorganic passivation layer system can for instance reduce or slow down a silicon carbide oxidation, e.g. an oxidation of the SiC semiconductor body aside or below the inorganic passivation layer system. Such an oxidation might be triggered or driven by humidity, e.g. in combination with electrical fields.
Data Source
AI summary
The disclosure relates to a semiconductor die, comprising a silicon carbide (SiC) semiconductor body; a passivation system on a first side of the SiC semiconductor body; the passivation system comprising an inorganic passivation layer system and an organic layer on the inorganic passivation layer system, a lateral edge of the inorganic passivation layer system arranged on the SiC semiconductor body, wherein the inorganic passivation layer system is laterally set back under the organic layer, the lateral edge of the inorganic passivation layer system being covered by the organic layer.