SiC Ohmic Electrode Oxidation Control
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Solution Overview
Problem
The challenge in manufacturing semiconductor devices using silicon carbide (SiC) is the increase in contact resistance due to oxidation of titanium and aluminum components in ohmic contact electrodes, which leads to higher electrical resistance and manufacturing costs, as well as limitations in integrating n-type and p-type regions.
Innovation Solution
The method involves forming an ohmic contact electrode alloyed with titanium, aluminum, and silicon, and then maintaining the electrode at 100°C or lower in an oxygen-containing atmosphere to prevent oxidation, or covering it with a metal front surface electrode pad to suppress the formation of high-resistance layers, thereby reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium and aluminum are used as electrode materials for contact with SiC regions, then contact resistance can be lowered, but oxidation occurs leading to increased electrical resistance
Solution Approach 1:
The patent uses a composite electrode structure consisting of multiple layers: a base layer of titanium and aluminum for low contact resistance, an intermediate layer of silicon carbide for protection, and a top layer of metal for oxidation resistance. This composite structure combines the advantages of each material while mitigating their individual disadvantages.
Solution Approach 2:
The patent employs an inert atmosphere (nitrogen or vacuum) during the heating process to prevent oxidation of the titanium and aluminum components. By replacing oxygen with an inert gas or vacuum environment, the harmful oxidation reaction is eliminated while allowing the beneficial alloying process to occur.
2Reliability
If different electrode materials are used for n-type and p-type regions, then contact resistance is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent develops a universal electrode structure that can be applied to both n-type and p-type SiC regions. The multi-layer composition (titanium-aluminum-silicon carbide-metal) serves as a universal solution that provides low contact resistance for both conductivity types, eliminating the need for different material selections and simplifying the manufacturing process.
Solution Approach 2:
The patent merges the functions of multiple materials into a single integrated electrode structure. Instead of using separate electrode materials for n-type and p-type regions, the combined multi-layer structure performs the contact function for both region types, reducing the number of manufacturing steps and material inventory requirements.
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 allows for semiconductor devices that can effectively contact both n-type and p-type SiC regions with reduced contact resistance, lowering manufacturing costs and improving integration by preventing oxidation and high-resistance layer formation.
Implementation Method 1
maintaining the electrode at 100°C or lower in an oxygen-containing atmosphere to prevent oxidation
Implementation Method 2
the deposited layers are annealed to convert at least a part of the deposited layers to aluminum-titanium-silicide
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
In order to provide a method of manufacturing a semiconductor device that can be in contact with both of an n-type SiC region and a p-type SiC region and can suppress increase in contact resistance due to oxidation, a method of manufacturing a semiconductor device in accordance with the present invention is a method of manufacturing a semiconductor device (1) including the steps of preparing a SiC layer (12) composed of silicon carbide, and forming an ohmic electrode (16) on a main surface of the SiC layer (12). The step of forming the ohmic electrode (16) includes the steps of forming a conductor layer (51, 52, 53) which will become the ohmic electrode (16) on the main surface of the SiC layer (12), and performing heat treatment such that the conductor layer (51, 52, 53) becomes the ohmic electrode (16). After the step of performing the heat treatment, a temperature of the ohmic electrode (16) when a surface of the ohmic electrode (16) is exposed to an atmosphere containing oxygen is set to 100°C or lower.