SiC MPS Diode Reaction Suppression Layer
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Solution Overview
Problem
The existing MPS structure for SiC Schottky barrier diodes faces challenges in achieving high reliability due to interface peeling between Schottky and ohmic electrodes caused by material reactions and natural oxide films, leading to poor contact resistance and surge tolerance.
Innovation Solution
A semiconductor device with a reaction suppression layer made of materials like TiN, Ti, Mo, or W is introduced between the ohmic and Schottky electrodes, preventing direct contact and subsequent material reactions, and a main electrode is formed on this layer to ensure electrical connection without peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electrode material is used to form both Schottky and ohmic contacts, then device complexity is reduced, but it becomes very difficult to achieve favorable Schottky contact and ohmic contact characteristics simultaneously
Solution Approach 1:
The electrode structure is segmented into three distinct layers: a first electrode layer for ohmic contact with the p-type region, a second electrode layer for Schottky contact with the n-type layer, and a main electrode layer connecting both. This segmentation allows each layer to be optimized for its specific function, achieving both low contact resistance ohmic contact and favorable Schottky barrier characteristics simultaneously.
Solution Approach 2:
Different electrode layers are applied to different regions of the semiconductor structure. The first electrode layer is positioned to contact the p-type region where low resistance is needed, while the second electrode layer contacts the n-type layer where Schottky barrier formation is required. This local differentiation of material properties and contact characteristics enables simultaneous optimization of both contact types.
2Reliability
If heat treatment is performed at high temperatures to form ohmic electrodes, then ohmic contact resistance is reduced, but material reactions occur between electrode layers at 450°C or higher, forming reaction layers that cause interface peeling
Solution Approach 1:
A reaction suppression layer is introduced as an intermediary between the first electrode layer (Ti-Ni alloy) and the second electrode layer (Mo alloy). This intermediate layer prevents direct material reactions between the electrode layers during high-temperature heat treatment, eliminating the formation of reaction layers that would cause interface peeling, while still allowing both electrodes to achieve their desired contact characteristics.
3Reliability
If Ti-Ni alloy is used for ohmic electrodes and Mo alloy for Schottky electrode, then favorable contact characteristics are achieved, but material reactions occur between these specific materials at high temperatures, forming reaction layers
Solution Approach 1:
The reaction suppression layer serves as a protective intermediary specifically between the Ti-Ni alloy ohmic electrode and the Mo alloy Schottky electrode. This intermediate layer is positioned to prevent direct contact and chemical reactions between these specific materials during high-temperature heat treatment, thereby eliminating the formation of harmful reaction layer products while preserving the desired low contact resistance and Schottky barrier characteristics of both electrode materials.
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
This configuration enhances the reliability of the MPS structure by suppressing reactions and maintaining low contact resistance, resulting in a diode with improved surge tolerance and manufacturing ease.
Implementation Method 1
a conductive reaction suppression layer configured to contact the first electrode and the second electrode and to suppress a reaction between a material configuring the first electrode and a material configuring the second electrode
Data Source
AI summary
A semiconductor device having a main electrode connected to a first semiconductor region and a second semiconductor layer on a semiconductor substrate so that a pn-junction diode is formed with the first semiconductor region being interposed and a Schottky barrier diode is formed with the second semiconductor layer being interposed on a surface of the semiconductor substrate, the semiconductor device includes a first electrode configured to ohmic-contact the first semiconductor region; a second electrode configured to Schottky-contact the second semiconductor layer and not having a portion directly contacting the first electrode; and a conductive reaction suppression layer to suppress a reaction between a material configuring the first electrode and a material configuring the second electrode are provided on the surface of the semiconductor substrate, and the main electrode is electrically connected to the first electrode and the second electrode.