Constricted Semiconductor Mesa Drift Zone for Switching Loss Reduction
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Solution Overview
Problem
Semiconductor devices, such as IGFETs and RC-IGBTs, experience high dynamic switching losses due to the reverse recovery process, where charge carrier plasma is not effectively attenuated, leading to increased forward resistance and energy losses.
Innovation Solution
The semiconductor device incorporates a constricted section in the drift zone of the semiconductor mesa, with a minimum horizontal width smaller than the body zone, which enhances charge carrier plasma desaturation by reducing emitter efficiency during the desaturation mode, allowing for direct transition from desaturation to forward blocking mode without significant energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional drift zone design is used, then the semiconductor device can maintain good forward conduction, but dynamic switching losses increase due to ineffective charge carrier plasma attenuation
Solution Approach 1:
The drift zone is divided into a first drift zone section with a constricted semiconductor mesa and a second drift zone section without constriction. This local structural differentiation creates varying emitter efficiency across different regions, enabling effective charge carrier plasma attenuation in the constricted section while maintaining overall device functionality.
Solution Approach 2:
The drift zone is segmented into multiple sections with different geometric characteristics. The first drift zone section contains the constricted mesa that provides desaturation functionality, while the second drift zone section maintains standard geometry for normal operation, allowing the device to achieve both low switching losses and reliable plasma attenuation.
2Loss of energy
If the semiconductor mesa is constricted to reduce switching losses, then charge carrier plasma desaturation improves, but the device complexity increases
Solution Approach 1:
The invention modifies the geometric parameters of the semiconductor mesa by creating a constricted section with reduced width in the first drift zone section. This parameter change affects the emitter efficiency and charge carrier distribution, enabling plasma desaturation without requiring complex additional components or 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 design significantly reduces dynamic switching losses by effectively desaturating the charge carrier plasma, enabling efficient switching characteristics and maintaining full blocking capability during transitions.
Implementation Method 1
A minimum horizontal width of the constricted section parallel to the first surface is smaller than a maximum horizontal width of the body zone, which enhances charge carrier plasma desaturation by reducing emitter efficiency during the desaturation mode
Implementation Method 2
A drift zone forms a first pn junction with the body zone... maintaining full blocking capability during transitions
Data Source
AI summary
A semiconductor device includes a body zone in a semiconductor mesa, which is formed between neighboring control structures that extend from a first surface into a semiconductor body. A drift zone forms a first pn junction with the body zone. In the semiconductor mesa, the drift zone includes a first drift zone section that includes a constricted section of the semiconductor mesa. A minimum horizontal width of the constricted section parallel to the first surface is smaller than a maximum horizontal width of the body zone. An emitter layer between the drift zone and the second surface parallel to the first surface includes at least one first zone of a conductivity type of the drift zone.