SiC Contact Formation Using Carbon-Enriched Ohmic Interfaces
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Solution Overview
Problem
Current methods for creating Ohmic contacts on silicon carbide (SiC) substrates face challenges in achieving reliable and robust contacts, particularly at the backside, with limited process windows and issues related to adhesion and by-product formation, which affect the mechanical and electrical robustness of SiC-based semiconductor devices.
Innovation Solution
A method involving the modification of the silicon carbide substrate surface to create a carbon-enriched portion, followed by deposition of a metallic contact layer and thermal annealing to form a ternary metallic phase comprising metallic contact material, silicon, and carbon, which enhances the formation of a highly ordered, textured metallic layer for improved Ohmic contacts without the need for additional cleaning steps or dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to create Ohmic contacts on SiC substrates, then contact formation is achieved, but reliability and robustness are insufficient
Solution Approach 1:
The method performs preliminary carbon enrichment of the SiC substrate surface before contact layer deposition. This preliminary action modifies the substrate surface composition to facilitate better contact formation, ensuring carbon is available at the interface during subsequent thermal annealing to form the ternary metallic phase, thereby improving contact reliability
Solution Approach 2:
The invention creates a ternary metallic phase contact consisting of metal, silicon, and carbon components. This composite contact structure combines the advantages of metal conductivity with silicon carbide interface compatibility, resulting in enhanced mechanical robustness and electrical performance compared to conventional binary contacts
2Adaptability or versatility
If conventional contact formation methods are used, then contact is achieved, but process window is limited
Solution Approach 1:
The method changes the chemical composition parameter of the SiC substrate surface by enriching it with carbon before contact formation. This parameter modification broadens the process window by making the contact formation less sensitive to variations in thermal annealing conditions, allowing for greater manufacturing flexibility and tolerance
3Reliability
If conventional methods are used, then contact is formed, but adhesion issues and by-product formation occur
Solution Approach 1:
Carbon acts as an intermediary element at the interface between the metal contact layer and the SiC substrate. The preliminary carbon enrichment ensures sufficient carbon is available during thermal annealing to form the ternary metallic phase, preventing unwanted by-products and ensuring strong adhesion without requiring additional cleaning steps
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 results in reliable, robust, and low-resistance Ohmic contacts with improved mechanical and electrical conductivity, offering a larger process window and increased yield by eliminating by-product issues and enhancing the reliability of SiC-based semiconductor devices.
Implementation Method 1
thermal annealing of at least a part of the carbon-enriched silicon carbide portion of the silicon carbide substrate and at least a part of the contact layer, thereby generating a ternary metallic phase portion comprising at least the metallic contact material, silicon, and carbon
Data Source
AI summary
The disclosure relates to a method for manufacturing a contact on a SiC substrate, wherein the method includes: providing a crystalline SiC substrate; modifying a crystal structure in a surface area of the SiC substrate such that a carbon-enriched SiC portion is generated in the surface area; forming a contact layer on the SiC substrate by depositing a metallic contact material onto the surface area that includes the carbon-enriched SiC portion; and thermal annealing of at least a part of the carbon-enriched SiC portion of the SiC substrate and at least a part of the contact layer, such that a ternary metallic phase portion including at least the metallic contact material, silicon, and carbon is generated. Furthermore, SiC semiconductor devices are described, which include a crystalline SiC substrate and a contact layer including a ternary metallic phase portion directly in contact with the SiC substrate surface.