Curved Anode Structure to Prevent Passivation Cracks in SiC Power Elements
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Solution Overview
Problem
Silicon carbide power elements face failure due to cracking of passivation layers under high temperature and humidity conditions, leading to moisture ingress and reliability issues, particularly in harsh environments like coastal areas.
Innovation Solution
A semiconductor structure with a curved connection surface between the side wall and top wall of the anode layer, optimized lithography and etching conditions to reduce stress concentration at corners, and a passivation layer that covers the field oxide layer and connection surface, minimizing the risk of cracks and enhancing moisture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation layer is applied to protect the power element against moisture, then the element's reliability is improved, but the passivation layer cracks easily under thermal stress, leading to failure
Solution Approach 1:
The anode layer is designed with a curved connection surface instead of a sharp corner, creating a smooth transition between the side wall and top wall. This curvature eliminates stress concentration points that would otherwise cause the passivation layer to crack under thermal expansion and contraction, thereby maintaining passivation layer integrity while preserving moisture protection functionality.
2Ease of manufacture
If the anode layer has a sharp corner structure, then the manufacturing process is simpler, but stress concentrates at the corner causing passivation layer cracks
Solution Approach 1:
The connection surface between the side wall and top wall of the anode layer is formed with a curved profile, eliminating sharp corners that concentrate stress. This curvature distributes thermal stress evenly across the transition zone, preventing passivation layer cracks while maintaining manufacturing feasibility through controlled deposition or sputtering processes.
3Object-affected harmful factors
If the passivation layer coverage is extended to cover the connection surface, then moisture resistance is improved, but the risk of cracks increases due to stress concentration
Solution Approach 1:
By forming a curved connection surface on the anode layer, the patent enables the passivation layer to be deposited continuously over the transition zone without sharp corners. This curved geometry allows the passivation layer to conform smoothly, providing complete moisture protection while distributing stress evenly to prevent cracks, thus simultaneously improving both moisture resistance and stability.
Data Source
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AI summary
A semiconductor structure includes a substrate (110), a semiconductor epitaxial layer (120), an active region (121) and a terminal region (123), a field oxide layer (130), an anode layer (140), and a passivation layer (150). The anode layer is configured to extend from the active region (121) to be arranged on a portion of the field oxide layer. The side wall (143) and the top wall (142) of the anode layer are connected to each other through a curved connection surface (144). By setting the upper corner of the side wall of the anode layer to be curved, the transition between the side wall and the top wall of the anode layer is smooth, preventing a sharp change in the inclination angle and preventing the stress concentration of the passivation layer (150) at the corner of the side wall.