SiC Junction Barrier Schottky Diode with Segmented Electrodes
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Solution Overview
Problem
Conventional junction barrier Schottky (JBS) structures face difficulties in achieving effective ohmic contact with P-type layers, limiting the utilization of their dual Schottky and PN diode properties due to the requirement for Schottky electrodes to contact N-type drift layers.
Innovation Solution
A SiC semiconductor device design featuring a Schottky barrier diode with both Schottky and ohmic electrodes, where the Schottky electrode contacts the drift layer through an insulation film and the ohmic electrode is on the substrate surface, along with a RESURF layer and P-type layers that provide a PN diode structure, allowing for both Schottky and PN diode properties to be utilized effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Schottky electrode contacts the N-type drift layer with Schottky contact, then the Schottky diode property is achieved, but it is difficult to provide ohmic contact with the P type layer
Solution Approach 1:
The Schottky electrode is divided into two distinct parts: a first Schottky electrode that contacts the N-type drift layer to provide Schottky diode property, and a second Schottky electrode that contacts the P-type layer to provide ohmic contact. This segmentation allows each part to fulfill its specific function without compromise.
Solution Approach 2:
Different regions of the Schottky electrode are designed with different contact properties: the first Schottky electrode region is optimized for Schottky contact with the N-type drift layer, while the second Schottky electrode region is optimized for ohmic contact with the P-type layer. This local differentiation resolves the contradiction by providing appropriate contact quality at each location.
2Adaptability or versatility
If a conventional JBS structure is used, then both Schottky and PN diode properties are present, but the advantage of the JBS structure cannot be utilized effectively due to inability to provide ohmic contact
Solution Approach 1:
The Schottky electrode is segmented into two functional parts to simultaneously achieve Schottky diode property (through the first Schottky electrode contacting N-type drift layer) and PN diode property (through the second Schottky electrode providing ohmic contact with P-type layer). This enables effective utilization of the JBS structure's dual properties.
Solution Approach 2:
The Schottky electrode is designed to perform multiple functions: it provides both Schottky diode property and PN diode property through its two distinct regions. This multi-functionality allows the single electrode structure to leverage both diode properties effectively, resolving the contradiction between adaptability and reliability.
3Reliability
If the Schottky electrode is made of metallic material capable of forming a Schottky barrier, then Schottky contact with N-type drift layer is achieved, but ohmic contact with P type layer becomes difficult
Solution Approach 1:
The Schottky electrode is divided into two segments with different material compositions or structures: the first Schottky electrode segment uses metallic material optimized for forming Schottky barriers with the N-type drift layer, while the second Schottky electrode segment is designed to provide ohmic contact with the P-type layer. This segmentation resolves the material selection contradiction.
Solution Approach 2:
Different regions of the Schottky electrode are assigned different material properties: the first region is composed of metallic material suitable for Schottky contact, while the second region is designed for ohmic contact. This local quality differentiation allows each region to optimize its contact performance with the respective semiconductor layer.
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 reduces leakage current and enhances breakdown voltage by enabling effective ohmic contact with P-type layers, effectively leveraging the dual diode properties of the JBS structure.
Implementation Method 1
An interface between the Schottky electrode and the semiconductor layer has a small work function between metallic material composing the Schottky electrode and semiconductor material composing the semiconductor layer
Implementation Method 2
The PN diode property provides I-V characteristics such that the diode breaks down at a comparatively large voltage, and then the current rapidly increases in avalanche manner
Implementation Method 3
The first Schottky electrode contacts each of the second conductive type layers with ohmic contact
Data Source
AI summary
A semiconductor device having a junction barrier Schottky 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 of the insulation film and an ohmic electrode on the substrate; a terminal structure having a RESURF layer surrounding the cell region; and multiple second conductive type layers on an inner side of the RESURF layer. The second conductive type layers and the drift layer provide a PN diode. The Schottky electrode includes a first Schottky electrode contacting the second conductive type layers with ohmic contact and a second Schottky electrode contacting the drift layer with Schottky contact.