SiC Trench Contact Shielding for Gate Reliability
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Solution Overview
Problem
Semiconductor devices based on silicon carbide face challenges due to high interface states between the SiC semiconductor body and dielectric layers, which affect mobility and concentration of charge carriers, and the breakdown strength is not fully exploited due to limitations in electric field strength and gate dielectric reliability.
Innovation Solution
A trench gate structure with a trench contact structure, source, body, diode, and shielding regions of specific conductivity types are formed within a silicon carbide semiconductor body, including a shielding region at a lateral distance from the trench gate structure to enhance breakdown strength and reliability, and a method for manufacturing these structures to optimize device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional planar contact structure is used, then the device layout is simple, but the breakdown strength is not fully exploited due to electric field concentration
Solution Approach 1:
The contact structure is segmented into a trench contact structure with a shielding region separated from the gate structure, dividing the electric field management into distinct zones. This segmentation allows the shielding region to specifically address breakdown strength at the contact-gate interface without complicating the overall device layout
Solution Approach 2:
A shielding region of second conductivity type is introduced as an intermediary element between the trench contact structure and the trench gate structure. This shielding region acts as a mediator to redistribute and reduce the electric field strength at critical interfaces, preventing breakdown while maintaining structural simplicity
2Strength
If the gate dielectric thickness is reduced to increase electric field strength, then the breakdown strength utilization improves, but the gate dielectric reliability decreases
Solution Approach 1:
The shielding region is positioned in advance to counteract the formation of high electric field concentrations at the gate dielectric interface. By preemptively redistributing the electric field before breakdown can occur, the shielding region allows thinner gate dielectrics to be used without compromising reliability
Solution Approach 2:
The shielding region serves as an intermediary that decouples the relationship between gate dielectric thickness and electric field strength. It enables the use of thinner dielectrics for higher field strength while the shielding region absorbs the stress, maintaining dielectric reliability
3Reliability
If interface states between SiC and dielectric layer are present, then charge carriers occupy these states, but charge carrier mobility and concentration are reduced
Solution Approach 1:
The shielding region acts as an intermediary layer that reduces the interaction between charge carriers and interface states at the SiC-dielectric interface. By redistributing the electric field, the shielding region minimizes carrier trapping at interface states, thereby preserving charge carrier mobility and concentration
Data Source
AI summary
A semiconductor device is proposed. A trench gate structure extends from a first surface into a silicon carbide semiconductor body along a vertical direction. A trench contact structure extends from the first surface into the silicon carbide semiconductor body along the vertical direction. A source region of a first conductivity type and a body region of a second conductivity type adjoin a first sidewall of the trench gate structure. A diode region of the second conductivity type adjoins a second sidewall of the trench gate structure opposite to the first sidewall. A shielding region of the second conductivity type adjoins a bottom of the trench contact structure, the shielding region being arranged at a lateral distance to the trench gate structure.