SiC Diode Surge Current via Segmented P-Well and High Resistance Region
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Solution Overview
Problem
Silicon carbide diodes face challenges in achieving high surge current capability due to high forward voltage drop and poor temperature management, leading to limited energy conversion efficiency and reliability issues.
Innovation Solution
A silicon carbide diode design featuring an N-type high resistance region under or on the P-type well region, with grooves and block-shaped P-type regions, enhances surge current capacity by increasing lateral resistance and effective PN junction opening, while maintaining low forward voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the area of the P-type well region is increased to enhance surge current capacity, then the surge current capability is improved, but the forward conduction voltage drop increases and energy conversion efficiency deteriorates
Solution Approach 1:
The P-type well region is segmented into multiple isolated P-type well regions distributed in the drift region, rather than using a single large P-type well region. This segmentation allows the device to achieve sufficient surge current capacity through distributed current paths while maintaining lower forward conduction voltage drop by reducing the total conductive area of the P-type regions.
Solution Approach 2:
The invention introduces an N-type high resistance region specifically under the P-type well region to create localized high electric field zones. This local modification enables the PN junction to turn on more effectively during surge current events without requiring a large overall P-type well area, thus maintaining low forward conduction loss while enhancing surge current capability.
2Reliability
If the area of the P-type well region is increased to improve surge current capacity, then the surge current capability is improved, but the device complexity increases
Solution Approach 1:
The P-type well region is divided into multiple small isolated regions rather than one large continuous region. This segmentation simplifies the overall device structure by using repeated modular units that are easier to manufacture and control, while still providing sufficient surge current capacity through the cumulative effect of multiple current paths.
Solution Approach 2:
The invention changes the electrical parameters by introducing an N-type high resistance region with specific resistivity characteristics (10^-3 to 10^-1 Ω·cm) under the P-type well region. This parameter modification enables effective PN junction turn-on during surge current without requiring complex structural modifications, thus improving surge current capability while maintaining structural simplicity.
3Loss of energy
If the forward conduction voltage drop is reduced to improve energy efficiency, then the energy conversion efficiency is improved, but the surge current capability deteriorates
Solution Approach 1:
The N-type high resistance region is locally introduced under the P-type well region to create a localized high electric field zone. This local modification enables effective PN junction turn-on during surge current events without affecting the overall forward conduction characteristics, thus maintaining low forward voltage drop while enhancing surge current capability.
Solution Approach 2:
The N-type high resistance region acts as an intermediary layer between the P-type well region and the N-type drift region. This intermediary structure facilitates effective charge injection and PN junction turn-on during surge current events, enabling the device to achieve high surge current capability without increasing the forward conduction voltage drop.
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 design significantly improves surge current capability and energy conversion efficiency by effectively managing electron current flow and reducing on-resistance, thereby enhancing the device's operational reliability and efficiency.
Implementation Method 1
an N-type high resistance region is provided under the P-type well region or on the lower surface of the P-type well region. The resistivity of the N-type high resistance region is greater than the resistivity of the N-type silicon carbide epitaxial layer.
Implementation Method 2
Under the condition of large current (when the surge current comes), the PN junction conducts and injects minority carrier electron holes into the drift region of the device, so as to enhance the surge current capacity of the device.
Implementation Method 3
In the normal conduction state (a small current) of the device, only the Schottky contact region conducts and the P-type well region does not conduct an electric current.
Data Source
AI summary
A silicon carbide diode having a high surge current capability, and including a semiconductor base plate. The semiconductor base plate includes an N-type silicon carbide substrate and an N-type silicon carbide epitaxial layer located on the N-type silicon carbide substrate. The upper portion of the N-type silicon carbide epitaxial layer is provided with a plurality of P-type well regions. The N-type high resistance region is provided under the P-type well region or on the lower surface of the P-type well region. The resistivity of the N-type high resistance region is greater than the resistivity of the N-type silicon carbide epitaxial layer. The N-type high resistance region is provided under the P-type well region, and a plurality of grooves are provided in the P-type well region or a plurality of block-shaped P-type regions uniformly arranged at intervals are provided in the N-type high resistance region.