IGBT Field Stop Layer Impurity Profile for EMI Noise Reduction
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Solution Overview
Problem
Field stop (FS) type Insulated Gate Bipolar Transistors (IGBTs) exhibit increased electromagnetic interference (EMI) noise due to their fast switching characteristics during turn-off switching, which is not effectively mitigated by existing technologies.
Innovation Solution
A power device structure is designed with a first and second field stop layer, epitaxially grown drift regions, and a buried region, where the impurity concentration profiles are optimized to minimize EMI noise by reducing the current tail of holes during turn-off switching, and the second field stop layer is formed with a higher impurity concentration than the first field stop layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fast switching characteristic is implemented in FS-IGBT, then switching speed is improved, but EMI noise increases
Solution Approach 1:
The patent introduces a second field stop layer with higher impurity concentration than the first field stop layer, creating a localized region with different electrical properties. This local quality change allows the device to maintain fast switching while reducing EMI noise by controlling carrier distribution in the specific region between the two field stop layers.
Solution Approach 2:
The patent changes the impurity concentration parameter by introducing a second field stop layer with higher impurity concentration than the first field stop layer. This parameter change modifies the electrical characteristics of the device, enabling it to reduce EMI noise while maintaining fast switching performance.
2Object-generated harmful factors
If impurity concentration in second field stop layer is increased, then EMI noise is reduced, but device complexity increases
Solution Approach 1:
The patent divides the field stop region into two separate layers: a first field stop layer and a second field stop layer with higher impurity concentration. This segmentation allows the device to reduce EMI noise through the second layer while maintaining the functional benefits of the field stop structure, avoiding the need for complete redesign of the entire device.
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 power device achieves fast switching characteristics while significantly reducing EMI noise by preventing overshooting and minimizing excessive voltage increases during turn-off switching.
Implementation Method 1
a first drift region formed on the first field stop layer and having the first conductivity type in an impurity concentration lower than the first field stop layer, a second drift region formed on the buried region
Data Source
AI summary
A power device having fast switching characteristic, while keeping EMI noise to a minimum and a method of fabricating the same are provided. The power device includes a first field stop layer having a first conductivity type, a first drift region formed on the first field stop layer and having a first conductivity type in an impurity concentration that is lower than the first field stop layer, a buried region formed on the first drift region and having the first conductivity type in an impurity concentration that is higher than the first drift region, a second drift region formed on the buried region, a power device cell formed at an upper portion of the second drift region, and a collector region formed below the first field stop layer.