SiC Ohmic Contact Formation Using Self-Aligned Carbon-Rich Layers
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Solution Overview
Problem
The existing methods for forming ohmic contact regions in SiC-based electronic devices often result in undesired reactions and irregularities, which can lead to short-circuits and affect the long-term reliability and electrical properties of the devices.
Innovation Solution
The formation of ohmic contacts using carbon-rich layers, such as graphite or graphene, which are self-aligned with the implanted regions and formed through thermal decomposition of silicon carbide, avoiding the deposition of metal layers and minimizing the risk of short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal layers are deposited to form ohmic contacts, then electrical contact is achieved, but undesired reactions and irregularities occur leading to short-circuits
Solution Approach 1:
The patent removes metal layers from the ohmic contact formation process entirely. Instead of depositing metal, the invention uses a self-aligned carbon-rich layer formed by thermal decomposition of silicon carbide, which eliminates the harmful reactions between metal and semiconductor that cause irregularities and short-circuits.
Solution Approach 2:
The patent introduces a carbon-rich layer as an intermediary material between the silicon carbide substrate and the electrode. This carbon-rich layer, formed through controlled thermal decomposition, serves as a reliable ohmic contact material that avoids the harmful interactions associated with traditional metal deposits.
2Reliability
If conventional methods are used to form ohmic contacts, then contact is established, but contact area extension beyond implanted regions causes short-circuits
Solution Approach 1:
The patent performs preliminary implantation of dopant species to create conductive regions, then uses these pre-formed regions as templates for subsequent carbon-rich layer formation. The thermal decomposition process is confined to these implanted areas, ensuring the carbon-rich layer forms only where needed and prevents extension beyond the intended contact regions.
Solution Approach 2:
The patent creates localized carbon-rich layers with different properties from the bulk silicon carbide. Through controlled thermal decomposition at specific implanted regions, the carbon-rich layer forms only where dopant species have been introduced, providing locally optimized ohmic contact properties without affecting adjacent areas.
3Reliability
If thermal decomposition is used to form carbon-rich layers, then ohmic contacts with lower resistance are achieved, but high temperature processing is required
Solution Approach 1:
The patent optimizes the thermal decomposition parameters including temperature range (typically 1000-1500°C), heating rate, and holding time to achieve complete decomposition of silicon carbide into carbon-rich layers. By carefully controlling these parameters, the process forms reliable ohmic contacts while minimizing unnecessary thermal exposure and energy 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
This approach enables the creation of ohmic contacts with lower electrical resistance and improved reliability, maximizing the contact area without extending beyond the implanted regions, thus enhancing the overall performance and longevity of SiC-based electronic devices.
Implementation Method 1
formed through thermal decomposition of silicon carbide
Data Source
AI summary
A method for manufacturing a SiC-based electronic device, comprising the steps of: implanting, on a front side of a solid body made of SiC having a conductivity of an N type, dopant species of a P type thus forming an implanted region, which extends in the solid body starting from the front side and has a top surface coplanar with the front side; and generating a laser beam directed towards the implanted region in order to generate heating of the implanted region to temperatures comprised between 1500° C. and 2600° C. so as to form a carbon-rich electrical-contact region at the implanted region. The carbon-rich electrical-contact region forms an ohmic contact.