SiC Semiconductor Gate Insulation via Local Oxidation Control
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Solution Overview
Problem
The formation of a gate insulating film in silicon carbide semiconductor devices leads to the introduction of interstitial carbon, which increases the donor or acceptor concentration, thereby deteriorating the junction withstand voltage and overall withstand voltage of the semiconductor device.
Innovation Solution
The use of an oxidation-resistant insulating film to prevent the oxidation of the RESURF layer and the semiconductor substrate in the termination region, combined with a laminated structure for the gate insulating films to enhance film quality and prevent interstitial carbon formation, ensuring the gate insulating film is formed without oxidizing the termination region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the entire substrate surface is oxidized to form a uniform gate insulating film, then the gate insulating film coverage is complete, but the termination region is oxidized and interstitial carbon is generated, reducing overall device performance
Solution Approach 1:
Different regions of the substrate are given different oxidation properties: the device region is made oxidizable to form the gate insulating film, while the termination region is made oxidation-resistant by covering it with an oxidation-resistant insulating film. This local differentiation of oxidation properties ensures complete gate insulating film coverage in the device region while preventing harmful oxidation in the termination region.
Solution Approach 2:
The oxidation-resistant insulating film is formed in advance over the termination region before the gate insulating film formation process. This preliminary protective action prevents oxidation of the termination region during subsequent processing steps, ensuring that the termination region remains free of interstitial carbon while the device region undergoes necessary oxidation.
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 improves the withstand voltage of the semiconductor device by preventing the formation of interstitial carbon, thus maintaining the integrity of the junction and overall voltage handling capabilities.
Implementation Method 1
an oxidation-resistant insulating film is formed on the semiconductor substrate in the termination region
Implementation Method 2
the gate insulating film is formed by oxidizing a surface of the semiconductor substrate in the device region
Data Source
Figure 1
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AI summary
A semiconductor device includes: a first conductivity type semiconductor substrate made of silicon carbide; a second conductivity type body region in a device region of the semiconductor substrate; a first conductivity type source region formed in the body region; and a gate electrode formed on the body region through gate insulating films. The semiconductor device further includes, in a termination region of the semiconductor substrate, second conductivity type RESURF layers, and an edge termination region formed in the RESURF layers. Then, the RESURF layers and a front surface of the semiconductor substrate adjacent to the RESURF layers are covered by an oxidation-resistant insulating film.