SiC JBS Diode Surge Handling via Segmented P-Type Layers
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Solution Overview
Problem
SiC semiconductor devices with junction barrier Schottky diodes face breakdown due to electric field concentration during surges, as the depletion layer expands and concentrates the electric field at the boundary between the N− type layer and the RESURF layer, leading to potential device breakdown.
Innovation Solution
A SiC semiconductor device design featuring a SiC substrate with a drift layer, insulation film, Schottky and ohmic electrodes, a RESURF layer, and multiple P type layers with deeper depths than the RESURF layer, which disperses the electric field and forms a PN diode to handle surge currents effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a P type layer is disposed at the same depth as the RESURF layer to form a PN diode, then leak current is reduced when reverse voltage is applied, but electric field concentrates at the boundary between the N− type layer and the RESURF layer during surge, causing device breakdown
Solution Approach 1:
The patent applies local quality by creating different depth levels for different functional regions. The P type layers are positioned at varying depths: some at the same level as the RESURF layer to reduce leak current, while others extend deeper to disperss electric field concentration during surge events. This spatial differentiation of P type layer depths allows each region to optimize its local function without compromising overall device reliability.
2Reliability
If the depletion layer expands during surge, then the PN diode function is activated, but the depletion layer approaches the N− type layer causing electric field concentration and breakdown
Solution Approach 1:
The patent segments the P type layer structure into multiple depth levels rather than using a single uniform depth. This segmentation creates distinct functional zones: upper P type layers for leak current suppression and deeper P type layers for surge protection. During surge conditions, the depletion layer expansion is managed by this segmented structure, preventing concentration at any single critical point and thereby improving breakdown resistance while maintaining surge protection.
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
The design increases the surge withstand voltage by allowing surge current to flow through a wider area in the PN diode, reducing the likelihood of device breakdown and enhancing overall voltage handling capabilities.
Implementation Method 1
the Schottky electrode is disposed in the cell region and contacts the drift layer through the opening of the insulation film with Schottky contact
Implementation Method 2
The plurality of second conductive type layers and the drift layer provide a PN diode
Implementation Method 3
a region under multiple second conductive type layers receives the electric field concentration, thereby, the surge current can flow through wide area in the PN diode
Data Source
AI summary
A semiconductor device having a JBS diode includes: a SiC substrate; a drift layer on the substrate; an insulation film on the drift layer having an opening in a cell region; a Schottky barrier diode having a Schottky electrode contacting the drift layer through the opening and an ohmic electrode on the substrate; a terminal structure having a RESURF layer in the drift layer surrounding the cell region; and multiple second conductive type layers in the drift layer on an inner side of the RESURF layer contacting the Schottky electrode. The second conductive type layers are separated from each other. The second conductive type layers and the drift layer provide a PN diode. Each second conductive type layer has a depth larger than the RESURF layer.