SiC Schottky Diode Barrier Height via C-Plane Orientation
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Solution Overview
Problem
Conventional Schottky diodes with epitaxial layers formed on the (0001) Si surface of SiC substrates struggle to achieve sufficient reduction in reverse voltage leak current due to limited Schottky barrier height, typically reaching only about 1.0 eV.
Innovation Solution
A Schottky diode design where the epitaxial layer is formed on the (000-1) C surface of a SiC substrate, with a Schottky electrode made of Mo, and a heat treatment process between 200°C and 1000°C to achieve a Schottky barrier height of 1.3 to 1.7 eV, reducing leak current by forming appropriate ohmic and Schottky contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the epitaxial layer is formed on the (0001) Si surface of the SiC substrate, then the manufacturing process is conventional and simple, but the Schottky barrier height is limited to about 1.0 eV resulting in high leak current
Solution Approach 1:
The patent changes the crystal orientation parameter of the SiC substrate from (0001) Si surface to (000-1) C surface. This parameter change in substrate orientation enables the formation of a Schottky barrier with height of 1.3 to 1.7 eV, significantly reducing leak current compared to the conventional 1.0 eV barrier height achieved on (0001) Si surface.
2Reliability
If the Schottky barrier height is increased to reduce leak current, then the leak current decreases, but the manufacturing complexity increases due to specific substrate orientation requirements
Solution Approach 1:
The patent specifies the substrate orientation parameter as (000-1) C surface to achieve the desired Schottky barrier height of 1.3 to 1.7 eV. This parameter specification ensures consistent high-quality diodes with reduced leak current while maintaining manufacturability through clear process definitions.
Solution Approach 2:
The patent introduces a specific substrate orientation ((000-1) C surface) as an intermediary parameter that mediates between the Schottky electrode material properties and the resulting barrier height. This intermediary enables predictable control of electrical characteristics.
3Reliability
If heat treatment is applied at high temperature to optimize Schottky contact, then the barrier height increases to 1.3-1.7 eV, but the manufacturing process becomes more complex
Solution Approach 1:
The patent specifies heat treatment temperature parameters (200°C to 1000°C range) to optimize the Schottky barrier height. By controlling this thermal parameter, the barrier height is enhanced to 1.3-1.7 eV, significantly improving diode performance and reducing leak current.
Solution Approach 2:
The heat treatment process is applied as a preliminary step before forming the Schottky electrode contact. This preliminary thermal processing prepares the semiconductor surface to achieve the desired barrier height characteristics, ensuring optimal contact properties from the outset.
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 approach significantly decreases leak current to about 1/10 of the original level, compared to conventional designs, by optimizing the Schottky barrier height and contact quality, enhancing the diode's performance in high-speed switching applications.
Implementation Method 1
a heat treatment process between 200°C and 1000°C to achieve a Schottky barrier height of 1.3 to 1.7 eV
Data Source
AI summary
A schottky diode includes a SiC substrate which has a first surface and a second surface facing away from the first surface, a semiconductor layer which is formed on the first surface of the SiC substrate, a schottky electrode which is in contact with the semiconductor layer, and an ohmic electrode which is in contact with the second surface of the SiC substrate. The first surface of the SiC substrate is a (000-1) C surface, upon which the semiconductor layer is formed.