SiC PiN Diode VcNN Structure Reduces On-Resistance
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Solution Overview
Problem
Silicon carbide-based PiN diodes exhibit high on-resistance due to carbon vacancies formed during ion implantation, which increases contact resistance and reduces bipolar operation speed and switching efficiency.
Innovation Solution
Incorporating a VcNN structure in the silicon carbide layer by performing high-temperature heat treatment in a nitrogen gas atmosphere with low oxygen partial pressure, reducing carbon vacancy density and enhancing nitrogen impurity concentration gradients to minimize on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ion implantation is performed to form p-type regions in silicon carbide, then doping is achieved, but carbon vacancies are formed increasing contact resistance and on-resistance
Solution Approach 1:
The patent applies preliminary action by performing heat treatment in a nitrogen atmosphere before final device operation to pre-form the VcNN structure. This preliminary nitrogen incorporation during heat treatment reduces carbon vacancies before they can cause harmful effects during device operation, thereby reducing on-resistance and improving contact properties
Solution Approach 2:
The patent converts the harmful carbon vacancies into beneficial structures by introducing nitrogen atoms that occupy these vacancy sites. The previously harmful carbon vacancies become beneficial VcNN structures that reduce contact resistance and improve electrical properties, transforming the defect into a functional feature
2Object-affected harmful factors
If nitrogen is incorporated to reduce carbon vacancies, then on-resistance decreases, but manufacturing process complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing heat treatment parameters (temperature range of 1000-2000°C, nitrogen atmosphere composition, treatment duration) to achieve the desired VcNN structure formation. By carefully controlling these parameters, the process achieves effective carbon vacancy reduction without requiring excessively complex multi-step procedures
Solution Approach 2:
The patent uses an inert nitrogen atmosphere during heat treatment to prevent oxidation while facilitating nitrogen incorporation into carbon vacancy sites. The nitrogen atmosphere serves dual purposes: protecting the silicon carbide from oxidation and providing the nitrogen source for VcNN structure formation, thereby simplifying the overall process
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 VcNN structure reduces on-resistance by eliminating localized states in the band gap, improving hole lifetime and conductivity modulation, thereby enhancing the performance of silicon carbide PiN diodes.
Implementation Method 1
a first p-type silicon carbide region disposed in the silicon carbide layer between the n-type silicon carbide region and the first electrode and having a second nitrogen concentration higher than the first nitrogen concentration, and a second p-type silicon carbide region disposed in the silicon carbide layer between the first p-type silicon carbide region and the first electrode, having a third nitrogen concentration higher than the second nitrogen concentration
Implementation Method 2
Incorporating a VcNN structure in the silicon carbide layer by performing high-temperature heat treatment in a nitrogen gas atmosphere with low oxygen partial pressure
Implementation Method 3
Carbon vacancies are formed during ion implantation, which increases contact resistance
Data Source
AI summary
A semiconductor device according to an embodiment includes a first electrode; a second electrode; a silicon carbide layer disposed between the first electrode and the second electrode; an n-type silicon carbide region disposed in the silicon carbide layer and having a first nitrogen concentration; a first p-type silicon carbide region disposed in the silicon carbide layer between the n-type silicon carbide region and the first electrode and having a second nitrogen concentration higher than the first nitrogen concentration; and a second p-type silicon carbide region disposed in the silicon carbide layer between the first p-type silicon carbide region and the first electrode, having a third nitrogen concentration higher than the second nitrogen concentration, and having a p-type impurity concentration higher than that of the first p-type silicon carbide region.