Power Rectifier Barrier Modulation Layer
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Solution Overview
Problem
Conventional power semiconductor rectifiers face challenges in achieving low on-state voltage while maintaining high blocking capability, with existing solutions often requiring additional process steps and limited metal options for the contact layer, leading to increased costs and inefficiencies.
Innovation Solution
A power semiconductor rectifier with a thin barrier modulation layer having a higher doping concentration than the drift layer, which lowers the Schottky barrier height to decrease on-state voltage without compromising blocking capability, achieved through a single electrode layer material and specific doping concentrations, allowing for a dual Schottky barrier height configuration without additional process steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a Schottky contact is used to achieve low on-state resistance, then the on-state voltage is reduced, but the blocking capability decreases due to image force lowering at high electric field levels
Solution Approach 1:
The patent applies local quality by creating a non-uniform doping profile in the drift layer, with a higher doping concentration region adjacent to the Schottky contact and a lower doping concentration region further away. This allows the region near the contact to support lower on-state voltage while the bulk region maintains high blocking capability through lower doping and thicker effective drift length.
Solution Approach 2:
The patent changes the doping concentration parameter spatially within the drift layer, transitioning from a uniform doping profile to a graded or multi-region profile. The first region has doping concentration of 1×10^16 to 1×10^18 atoms/cm³ while the second region has 1×10^14 to 1×10^16 atoms/cm³, optimizing both electrical parameters simultaneously.
2Reliability
If p-type emitter regions are added to improve blocking capability, then the breakdown voltage increases, but additional process steps are required
Solution Approach 1:
The patent extracts the blocking capability enhancement function from the traditional p-type emitter region approach and implements it through a doping-modified drift layer structure. The higher doping concentration region in the drift layer performs the field management function previously achieved by separate p-type regions, eliminating the need for additional doping steps and mask patterns.
Solution Approach 2:
The patent merges the drift layer and the field management function into a single integrated structure. The drift layer simultaneously serves as the current conduction path and the electric field management region through its non-uniform doping profile, combining functions that were traditionally separated into different layers or regions.
3Reliability
If the drift layer thickness is increased to improve blocking capability, then the breakdown voltage increases, but the on-state resistance increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform doping profile in the drift layer, with a higher doping concentration region adjacent to the Schottky contact and a lower doping concentration region further away. This allows the region near the contact to support lower on-state voltage while the bulk region maintains high blocking capability through lower doping and thicker effective drift length.
Solution Approach 2:
The patent changes the doping concentration parameter spatially within the drift layer, transitioning from a uniform doping profile to a graded or multi-region profile. The first region has doping concentration of 1×10^16 to 1×10^18 atoms/cm³ while the second region has 1×10^14 to 1×10^16 atoms/cm³, optimizing both electrical parameters simultaneously.
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 effectively reduces on-state voltage while maintaining high blocking capability, improving carrier injection and tunneling, and enabling efficient manufacturing with reduced costs by using a single electrode layer material, thus enhancing the performance and manufacturing efficiency of power semiconductor rectifiers.
Implementation Method 1
The first main side 3 of SiC wafer, which is the anode side of the device, is covered with a first metal contact layer 5 that forms a Schottky contact with the drift layer 2
Implementation Method 2
image force lowering at elevated electric field levels at high blocking voltages causes the barrier for electrons to shrink
Implementation Method 3
improving carrier injection and tunneling
Data Source
AI summary
It is the object of the invention to provide a power semiconductor rectifier with a low on-state-voltage and high blocking capability. The object is attained by a power semiconductor rectifier comprising: a drift layer having a first conductivity type; and an electrode layer forming a Schottky contact with the drift layer, wherein the drift layer includes a base layer having a peak net doping concentration, below 1·1016 cm−3 and a barrier modulation layer which is in direct contact with the electrode layer to form at least a part of the Schottky contact, wherein a net doping concentration of the barrier modulation layer is in a range between 1·1016cm−3 and 1·1019 cm−3 and wherein the barrier modulation layer has a layer thickness in a direction vertical to the interface between the electrode layer and the barrier modulation, layer of at least 1 nm and less than 0.2 μm.