IGBT Body Region Low Doping for Switching Loss Reduction
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Solution Overview
Problem
Semiconductor devices, particularly Insulated Gate Bipolar Transistors (IGBTs), face high switching losses due to the accumulation charge during reverse conducting operations, which affects their efficiency in applications like power supplies and electric motor driving.
Innovation Solution
The semiconductor device incorporates a field effect transistor structure with a body region having a low doping dose portion extending from the source region or electrical contact interface to the drift region, with a doping dose less than three times the breakdown charge, and includes a diode region forming a pn-junction with the drift region, separated from the body region, to optimize the reverse conducting operation mode and reduce switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the body region has a higher doping dose, then the emitter efficiency increases and current conduction improves, but the reverse recovery charge increases and switching losses increase
Solution Approach 1:
The body region is divided into two zones with different doping doses: a first zone with higher doping dose for good current conduction and a second zone with lower doping dose (less than 3 times breakdown charge) for reduced reverse recovery charge. This local differentiation allows simultaneous optimization of both forward conduction and reverse switching characteristics.
Solution Approach 2:
The doping dose parameter in the body region is optimized to be less than 3 times the breakdown charge, representing a significant reduction from conventional high doping doses. This parameter change directly reduces the accumulation charge during reverse conducting operations while maintaining adequate forward current capability through the higher doping first zone.
2Loss of energy
If the doping dose in the body region is reduced, then the reverse recovery charge decreases and switching losses reduce, but the emitter efficiency decreases and current conduction capability worsens
Solution Approach 1:
The body region employs spatially varying doping concentrations with a first zone maintaining higher doping for current conduction and a second zone with reduced doping for low reverse recovery charge, thus locally optimizing both contradictory requirements.
Solution Approach 2:
The body region is segmented into multiple zones with different doping characteristics, allowing independent optimization of each zone's function - the first zone handles forward current conduction while the second zone minimizes reverse recovery effects.
3Loss of energy
If a separate diode region is introduced, then the reverse conducting operation mode is optimized and switching losses reduce, but the device structure becomes more complex
Solution Approach 1:
The diode function is merged with the body region by forming a separate diode region that shares the same semiconductor substrate and drift region, rather than using a completely independent diode structure. This integration reduces overall device complexity while achieving optimized reverse conducting operation.
Solution Approach 2:
The body region serves dual functions: it provides the transistor body for forward conduction mode and simultaneously forms a pn-junction with the drift region to enable diode operation in reverse conducting mode. This multi-functionality eliminates the need for separate dedicated diode structures.
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 lowers the emitter efficiency and keeps the reverse recovery charge low, thereby reducing switching losses and improving the semiconductor device's performance in switching applications.
Implementation Method 1
The body region comprises at least one low doping dose portion extending from the drift region to at least one of the source region or an electrical contact interface of the body region at a main surface of the semiconductor substrate, wherein a doping dose within the low doping dose portion is less than 3 times the breakdown charge
Implementation Method 2
a diode region of the second conductivity type forming a pn-junction with the drift region separated from the body region
Implementation Method 3
the resistance of the device can be controlled by the voltage applied to the gate electrode of the IGBT
Data Source
AI summary
A semiconductor device includes at least one field effect transistor structure, which is formed on a semiconductor substrate. The field effect transistor structure includes a drift region, a body region, a source region and a gate. The source region and the drift region include at least mainly a first conductivity type, wherein the body region includes at least mainly a second conductivity type. The body region includes at least one low doping dose portion extending from the drift region to at least one of the source region or an electrical contact interface of the body region at a main surface of the semiconductor substrate, wherein a doping dose within the low doping dose portion of the body region is less than 3 times a breakdown charge.