SiC Cell Segmented Source Body Contact Layout
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Solution Overview
Problem
Existing semiconductor devices, particularly those using silicon carbide (SiC), face challenges in minimizing on-state conduction losses due to high channel and JFET region resistances, which are significant contributors to overall device performance and efficiency, especially in high-voltage and high-temperature applications.
Innovation Solution
The implementation of a segmented source and body contact (SSBC) cellular device layout, where the body contact region is not centered and is only partially surrounded by the source contact region, enhances channel width and JFET density, thereby reducing channel and JFET region resistances, and optimizing device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional centered body contact layout is used, then the device structure is simple and easy to manufacture, but the channel width is reduced and JFET density is low resulting in high channel and JFET region resistances
Solution Approach 1:
The patent applies asymmetry by positioning the body contact region off-center within the semiconductor device cell, specifically adjacent to one channel region rather than centered. This asymmetric placement increases the effective channel width and enhances JFET density in the drift region, thereby reducing channel and JFET region resistances that contribute to on-state conduction losses.
Solution Approach 2:
The patent utilizes dimensional optimization by adjusting the relative positions and dimensions of the body contact region, source contact region, and channel regions. By moving the body contact off-center and optimizing its placement adjacent to specific channel regions, the design effectively increases the active channel width and JFET region volume without increasing the overall device footprint, thus reducing resistance losses.
2Length of moving object
If the body contact region is centered in the semiconductor device cell, then the layout is symmetric and easier to fabricate, but the channel width is limited and JFET density is reduced
Solution Approach 1:
The patent deliberately employs asymmetric positioning of the body contact region adjacent to one channel region rather than centering it. This asymmetric configuration maximizes the effective channel width by allowing the source contact region to extend further on one side, thereby increasing the active channel area and improving current conduction capability.
3Reliability
If the source contact region completely surrounds the body contact portion, then the contact structure is more robust, but the JFET density is reduced and channel resistance increases
Solution Approach 1:
The patent applies local quality by making the source contact region partially surround the body contact portion rather than completely surrounding it. This partial surrounding configuration is strategically designed to maintain sufficient mechanical and electrical contact reliability while simultaneously increasing the JFET density in the drift region. The selective partial enclosure allows for optimized local field distribution and enhanced JFET region utilization, thereby reducing channel resistance losses.
Data Source
AI summary
A method of fabricating a semiconductor device cell at a surface of a silicon carbide (SiC) semiconductor layer includes forming a segmented source and body contact (SSBC) of the semiconductor device cell over the surface of the SiC semiconductor layer. The SSBC includes a body contact portion disposed over the surface of the semiconductor layer and proximate to a body contact region of the semiconductor device cell, wherein the body contact portion is not disposed over the center of the semiconductor device cell. The SSBC also includes a source contact portion disposed over the surface of the semiconductor layer and proximate to a source contact region of the semiconductor device cell, wherein the at least one source contact portion only partially surrounds the body contact portion of the SSBC.