SiC Schottky Diode Passivation Structure for Environmental Protection
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Solution Overview
Problem
Current passivation techniques for semiconductor devices, such as Schottky diodes, are inadequate in withstanding extreme environmental conditions and elevated operating levels, leading to performance deterioration and device failure.
Innovation Solution
A passivation structure comprising a first silicon nitride layer, a silicon dioxide layer, and a second silicon nitride layer, deposited using a single plasma-enhanced chemical vapor deposition (PECVD) process, is applied to cover the edge termination region and sides of the Schottky contact, providing enhanced protection against environmental elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current passivation techniques are used to encapsulate semiconductor devices, then device protection against environmental elements is provided, but device reliability under extreme environmental conditions deteriorates
Solution Approach 1:
The patent applies a multi-layer composite passivation structure consisting of alternating layers of silicon nitride and silicon dioxide deposited by PECVD. This composite structure provides superior protection against environmental elements (moisture, oxygen, hydrogen) compared to single-layer passivation, thereby improving device reliability under extreme environmental conditions while effectively blocking harmful factors
Solution Approach 2:
The patent changes the deposition parameters by using PECVD (plasma-enhanced chemical vapor deposition) to deposit the passivation layers at controlled temperatures and plasma conditions. This process parameter change enables the formation of high-quality, low-stress nitride layers with excellent barrier properties, improving the effectiveness of environmental protection without compromising device performance
2Duration of action of stationary object
If passivation structures are added to protect semiconductor devices, then device longevity is improved, but device complexity increases
Solution Approach 1:
The passivation structure is segmented into multiple thin layers (alternating nitride and oxide layers) rather than using a single thick layer. This segmentation allows each layer to provide specific protective functions (nitride for moisture barrier, oxide for stress management and adhesion), achieving superior long-term protection while keeping individual layers thin and manageable to minimize overall structural complexity
Solution Approach 2:
The patent merges multiple protective functions into a single integrated passivation structure that combines moisture blocking, stress management, and adhesion enhancement in one deposited stack. This merging approach achieves comprehensive protection for improved device longevity while avoiding the complexity of multiple separate passivation structures
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 improved passivation structure significantly increases the longevity of Schottky diodes, allowing them to operate at 80% of the rated reverse breakdown voltage at 85% humidity and 85°C for at least 1000 hours without failure, representing a substantial improvement over existing technologies.
Implementation Method 1
deposited using a single plasma-enhanced chemical vapor deposition (PECVD) process
Implementation Method 2
The oxide layer may be thermally grown
Data Source
AI summary
A Schottky diode is disclosed that includes a silicon carbide substrate, a silicon carbide drift layer, a Schottky contact, and a passivation structure. The silicon carbide drift layer provides an active region and an edge termination region about the active region. The Schottky contact has sides and a top extending between the two sides and includes a Schottky layer over the active region and an anode contact over the Schottky layer. The passivation structure covers the edge termination region, the sides of the Schottky contact, and at least a portion of the top of the Schottky contact. The passivation structure includes a first silicon nitride layer, a silicon dioxide layer over the first silicon nitride layer, and a second silicon nitride layer over the silicon dioxide layer.