SiC Electrode Contact via 3C-SiC Surface Conversion
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Solution Overview
Problem
The provision of a silicide layer, such as nickel silicide, for ensuring ohmic contact between a silicon carbide semiconductor layer and an electrode often causes surface roughness, affecting the reliability of the product.
Innovation Solution
A silicon carbide semiconductor device is designed with a first semiconductor layer of 4H-SiC and a second semiconductor layer of 3C-SiC at the top surface, where the impurity concentration is 1×1018/cm3 or higher within 0.3 micrometers and 1×1017/cm3 or lower at 0.5 micrometers depth, and a main electrode is formed on the top surface side of the second semiconductor layer by oblique ion implantation at an angle of 30 degrees or greater and less than 90 degrees.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicide layer (e.g., nickel silicide) is provided to ensure ohmic contact between silicon carbide semiconductor layer and electrode, then electrical contact quality is improved, but surface roughness occurs affecting product reliability
Solution Approach 1:
The invention removes the silicide layer from the contact structure between the semiconductor layer and electrode. By directly contacting the electrode with the silicon carbide semiconductor layer, the harmful silicide layer is extracted/eliminated, preventing surface roughness while maintaining ohmic contact through proper doping and crystal structure control
Solution Approach 2:
The invention changes the crystal structure parameter of the semiconductor layer from 4H-SiC to 3C-SiC at the contact region, and controls impurity concentration parameters (1×10^18/cm³ to 1×10^17/cm³ gradient). These parameter changes enable direct ohmic contact without silicide layer while maintaining electrical performance
2Reliability
If multiple process steps are used to form silicide layer for ohmic contact, then contact quality is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention eliminates the silicide layer formation process entirely by using direct contact between electrode and doped silicon carbide layer. This removes multiple process steps (silicide deposition, annealing, etc.) while achieving the same ohmic contact function through material structure optimization
Solution Approach 2:
The silicon carbide semiconductor layer serves multiple functions: it provides the semiconductor functionality, the ohmic contact interface, and the structural support. By making the semiconductor layer multi-functional, separate silicide layer processes are eliminated
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 configuration ensures an ohmic contact without the need for a silicide layer, reducing surface roughness issues and improving product reliability while minimizing process steps and costs.
Implementation Method 1
implanting dopant ions into the heated silicon carbide layer
Implementation Method 2
heating the silicon carbide layer to a temperature of 300° C. or more
Data Source
AI summary
Provided is a method of manufacturing a silicon carbide semiconductor device capable of ensuring an ohmic contact between a semiconductor layer including silicon carbide and an electrode without any silicide layer provided. The method of manufacturing the silicon carbide semiconductor device, includes: implanting impurity ions into a top surface of a first semiconductor layer including 4H-SiC in a direction inclined at an angle of 30 degrees or greater and less than 90 degrees to a normal line to the top surface of the first semiconductor layer so as to form a second semiconductor layer including 3C-SiC at least at a top surface on the top surface side of the first semiconductor layer; and forming a main electrode on the top surface side of the second semiconductor layer.