Silicon Carbide Ohmic Contact via Nitrogen Alloy
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Solution Overview
Problem
Conventional silicon carbide semiconductor devices face challenges in reducing the sheet resistance of ohmic electrodes, which hinders high-speed operation due to high contact resistance between the source electrode and the body region.
Innovation Solution
A silicon carbide semiconductor device with a p-type impurity region and an ohmic electrode made of a silicon alloy containing nitrogen, where the average nitrogen concentration in the ohmic electrode is higher than in the impurity region, and the p-type impurity concentration is controlled to reduce sheet resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet resistance of the ohmic electrode is reduced to enable high-speed operation, then the switching performance is improved, but the device structure becomes more complex
Solution Approach 1:
The patent merges the ohmic electrode with the contact region by forming the ohmic electrode as a silicon alloy containing nitrogen directly in the contact region. This integration eliminates the need for separate electrode structures and complex interfacial layers, achieving low sheet resistance while maintaining structural simplicity.
Solution Approach 2:
The patent uses composite material strategy by creating an ohmic electrode that is a silicon alloy containing nitrogen, with spatially varying impurity concentrations. This composite structure combines regions of high p-type impurity concentration (for low contact resistance) with regions of low p-type impurity concentration (for low sheet resistance), achieving both high-speed operation and structural efficiency.
Data Source
AI summary
A semiconductor device includes: a first silicon carbide semiconductor layer; a p-type first impurity region provided in the first silicon carbide semiconductor layer; and a first ohmic electrode forming ohmic contact with the p-type first impurity region. The first ohmic electrode is a silicon alloy containing nitrogen, an average concentration of nitrogen in the first ohmic electrode is higher than or equal to one half of an average concentration of nitrogen in the first impurity region, and an average concentration of a p-type impurity in a portion of the first ohmic electrode except a portion of the first ohmic electrode within 50 nm from an interface between the first ohmic electrode and the first impurity region is equal to or lower than 3.0×1018 cm−3.