SiC Semiconductor Device with Auxiliary Electrode for Low On-Resistance
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Solution Overview
Problem
Power semiconductor devices face challenges in achieving low on-resistance and high breakdown voltage, which are necessary for reducing power loss and supporting large current flow, while also maintaining a high reverse voltage characteristic, due to the trade-off between epitaxial layer concentration and thickness.
Innovation Solution
A silicon carbide semiconductor device design that includes an n− type layer, a p type region, an auxiliary n+ type region, and electrodes, with a gate electrode separated from the auxiliary electrode and source electrode, allowing for improved current density and reduced on-resistance by facilitating electron and hole current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the epitaxial layer is made thick with low concentration to achieve high breakdown voltage, then the breakdown voltage is improved, but the on-resistance increases and forward direction current density decreases
Solution Approach 1:
The invention divides the drift region into multiple segments with different doping concentrations (first drift region with lower concentration and second drift region with higher concentration). This segmentation allows each region to contribute differently to the overall performance, with the lower concentration region providing high breakdown voltage and the higher concentration region providing low on-resistance, thereby resolving the contradiction between breakdown voltage and on-resistance
Solution Approach 2:
The invention applies local quality by creating regions with different doping concentrations at different locations within the drift region. The first drift region has lower doping concentration optimized for breakdown voltage, while the second drift region has higher doping concentration optimized for current conduction. This spatial variation in material properties allows simultaneous achievement of high breakdown voltage and low on-resistance
2Strength
If the epitaxial layer is made thick with low concentration to achieve high breakdown voltage, then the breakdown voltage is improved, but the forward direction current density decreases
Solution Approach 1:
The drift region is segmented into first and second drift regions with different doping concentrations. The second drift region with higher concentration provides a low-resistance path for forward current, thereby maintaining high current density even when the overall drift region thickness is increased for high breakdown voltage
Solution Approach 2:
By creating a localized high-concentration region (second drift region) within the drift structure, the invention provides a dedicated current conduction path that maintains high forward direction current density while the overall structure maintains high breakdown voltage capability
Data Source
AI summary
A semiconductor device may include an n− type layer sequentially disposed at a first surface of an n+ type silicon carbide substrate; a p type region disposed in the n− type layer; an auxiliary n+ type region disposed on the p type region or in the p type region; an n+ type region disposed in the p type region; an auxiliary electrode disposed on the auxiliary n+ type region and the p type region; a gate electrode separated from the auxiliary electrode and disposed on the n− type layer; a source electrode separated from the auxiliary electrode and the gate electrode; and a drain electrode disposed at a second surface of the n+ type silicon carbide substrate, wherein the auxiliary n+ type region and the n+ type region are separated from each other, and the source electrode is in contact with the n+ type region.