SiC Power Semiconductor Structure for Gate Oxide Field Shifting
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Solution Overview
Problem
Existing power semiconductor devices, such as Schottky MOSFET and IGBT devices, lack reliability due to the absence of metallurgical junctions to protect gate oxides, leading to potential degradation and performance issues.
Innovation Solution
A power semiconductor device with a base layer of silicon carbide and embedded zones of a second conductivity type to shift peak electric fields away from the insulation layer, utilizing a gate contact and contact layers with controlled overlap and doping profiles to enhance reliability and reduce on-state resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Schottky contacts are used without metallurgical junctions, then device structure is simplified and manufacturing is easier, but reliability deteriorates due to gate oxide degradation
Solution Approach 1:
An injecting layer of second conductivity type is introduced as an intermediary between the base layer and the electrode. This layer serves as a mediator that enables controlled carrier injection while maintaining the Schottky contact structure, thereby improving reliability without compromising manufacturing simplicity
Solution Approach 2:
The doping concentration of the injecting layer is optimized to balance between reliability improvement and manufacturing complexity. By carefully controlling the doping parameters, the device achieves enhanced gate oxide protection while maintaining ease of manufacture
2Reliability
If doping concentration in base layer is increased to improve reliability, then gate oxide protection is enhanced, but on-state resistance increases
Solution Approach 1:
Instead of uniformly increasing doping concentration throughout the base layer, the invention introduces a localized injecting layer with specific doping characteristics. This local modification provides gate oxide protection precisely where needed at the electrode interface, while keeping the bulk base layer doping low to maintain low on-state resistance
Solution Approach 2:
The base layer is functionally segmented into regions with different doping characteristics - the injecting layer with higher doping for reliability near the electrode, and the bulk base layer with lower doping for low resistance conduction. This segmentation resolves the contradiction between reliability and on-state resistance
3Productivity
If contact layer and gate contact overlap is increased to improve electrical performance, then current distribution is improved, but electric field peaks increase causing reliability issues
Solution Approach 1:
The injecting layer acts as an intermediary that mediates the interaction between the contact layer and gate contact. It enables improved current distribution through the contact layer while simultaneously managing the electric field distribution to prevent harmful peaks, thus resolving the contradiction between productivity and reliability
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 solution improves the reliability and reduces on-state resistance by evenly distributing current and minimizing electric field peaks, thereby enhancing the overall performance and production efficiency of the semiconductor device.
Implementation Method 1
at least one zone of a second conductivity type is provided within the base layer, wherein the at least one zone is constructed and arranged to shift away a peak electric field generated in the base layer from the insulation layer between the gate contact and the base layer
Data Source
AI summary
A power semiconductor device and method for production thereof is specified involving an electrode, a base layer of a first conductivity type provided on the electrode, at least one contact layer provided on the base layer, a gate contact provided on the base layer and on the at least one contact layer, an insulation layer between the gate contact and the base layer and between the at least one contact layer and the gate contact, and at least one zone of a second conductivity type within the base layer, wherein the at least one zone is constructed and arranged to shift away a peak electric field generated in the base layer from the insulation layer between the gate contact and the base layer.